Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0134 PM CDT Fri Aug 16 2019 Valid 171200Z - 181200Z An isolated dry-thunderstorm area has been added for northeast UT and northwest CO, where it appears that moisture and low/midlevel lapse rates will be sufficient to support isolated mostly dry storms Saturday afternoon, within a similar regime to D1/Friday. Otherwise, elevated to locally critical conditions are still expected across portions of the Snake River Plain and also across portions of eastern UT, western CO, and southern WY. The elevated area has been expanded somewhat to include more higher-terrain valleys, but the forecast reasoning remains the same. See the previous discussion below for more details. ..Dean.. 08/16/2019 .PREV DISCUSSION... /ISSUED 0149 AM CDT Fri Aug 16 2019/ ...Synopsis... An upper-level shortwave trough will move over the northern Rockies and northern Plains tomorrow with zonal upper-level flow prevailing across much of the CONUS. The dry slot of this shortwave trough will move over portions of the Intermountain West with stronger 700-500 mb flow stretching from southern Idaho into northern Utah, southern Wyoming, and northern Colorado. With daytime heating, this stronger flow should mix to the surface and overlap a dry airmass resulting in elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) across this area. Locally critical conditions are possible with portions of the Snake River Plain and Great Divide Basin/vicinity favored. However, there is enough uncertainty at this time to preclude introducing a critical area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Fri Aug 16 2019 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTH DAKOTA...NEBRASKA AND KANSAS EASTWARD INTO WESTERN ILLINOIS... ...SUMMARY... Severe storms are possible over parts of the northern and central Plains and upper Midwest on Saturday. A few strong storms are also possible from the Lower Great Lakes into western New England. ...Synopsis... A deep shortwave trough is expected to move eastward from the northern Rockies/northern High Plains through the northern Plains and into the Upper Midwest on Saturday. Progression of this system will help maintain the enhanced westerly flow aloft extending from the northern Rockies/eastern Great Basin eastward through the Great Lakes. In particular, strong mid-level flow attendant to the shortwave trough will move into the northern Plains Saturday afternoon and evening. Progression of this shortwave trough will also help push a cold front quickly through the northern Plains and Upper Midwest. Farther south, persistent westerly flow aloft will help maintain relatively cool mid-level temperatures and steep mid-level lapse rates atop a very warm and moist low-level air mass across the central Plains and mid MS Valley. ...Northern/Central Plains into the Middle MS Valley... Showers and thunderstorms will likely be ongoing across central/northern MO early Saturday as the nocturnal low-level jet persists into the early morning, supporting warm-air advection into the region. Given the abundance of antecedent precipitation, the expectation is for predominantly moist profiles with only modest instability. An isolated water-loaded downburst is possible. As the low-level jet diurnally weakens and the showers and thunderstorms gradually diminish across MO, additional showers and thunderstorms will likely be developing along the cold front as it moves through the western Dakotas early Saturday afternoon. Limited diurnal heating and less favorable low-level moisture should initially keep the severe threat isolated. Low-level moisture and resulting instability increase with eastern extent, suggesting higher severe thunderstorm coverage along the front as it moves into central SD and central NE during the late afternoon. As the front continues eastward during the evening, a nocturnal low-level jet is expected to develop from the southern Plains into the middle MS Valley. This should lead to an increase in showers and thunderstorms ahead of the front from eastern NE into northern MO, IA, and far northwest IL. Steep mid-level lapse rates and strong buoyancy will be in place and some of the initial development could pose a risk for severe hail. Additionally, as the storms along the front interact with these warm-air advection induced, storm mergers could lead to storm intensification and relatively higher severe probabilities. Hail and damaging wind gusts are the primary threats. ...Eastern CO and TX/OK Panhandles into eastern KS... A lee trough/dryline is expected to extend from the far western NE Panhandle southward through eastern CO and into the central TX/OK Panhandles. Large-scale forcing for ascent near this boundary will be negligible, except across northeast CO where modest large-scale ascent is possible from the shortwave trough farther north. Even so, isolated storms area possible along this boundary as temperatures climb into the upper 90s/low 100s and the boundary-layer mixes deeply. A strong wind gust or two with these high-based storms. Across eastern KS, remnant boundary from the antecedent MCS could provide the impetus for surface-based storms during the afternoon. However, despite ample low-level moisture, warm mid-level temperatures and the lack of stronger forcing for ascent cast doubt into storm initiation. If storms do develop, strong buoyancy and modest vertical shear would support supercells capable of all severe hazards, including very large hail and a tornado or two. ...Northeast OH across NY and into western New England... A low-amplitude shortwave trough is expected to move into western portions of the region during the early afternoon. Southwesterly low-level winds and heating will lead to around 1000 J/kg MUCAPE, with around 35-40 kt of effective shear. The approaching shortwave trough will provide the impetus for storm development beginning during the early afternoon from northern OH into western NY. While low-level shear will not be strong, effective SRH of 100-150 m2/s2 may support a brief supercell capable of damaging wind gusts and/or marginal hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 08/16/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Fri Aug 16 2019 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTH DAKOTA...NEBRASKA AND KANSAS EASTWARD INTO WESTERN ILLINOIS... ...SUMMARY... Severe storms are possible over parts of the northern and central Plains and upper Midwest on Saturday. A few strong storms are also possible from the Lower Great Lakes into western New England. ...Synopsis... A deep shortwave trough is expected to move eastward from the northern Rockies/northern High Plains through the northern Plains and into the Upper Midwest on Saturday. Progression of this system will help maintain the enhanced westerly flow aloft extending from the northern Rockies/eastern Great Basin eastward through the Great Lakes. In particular, strong mid-level flow attendant to the shortwave trough will move into the northern Plains Saturday afternoon and evening. Progression of this shortwave trough will also help push a cold front quickly through the northern Plains and Upper Midwest. Farther south, persistent westerly flow aloft will help maintain relatively cool mid-level temperatures and steep mid-level lapse rates atop a very warm and moist low-level air mass across the central Plains and mid MS Valley. ...Northern/Central Plains into the Middle MS Valley... Showers and thunderstorms will likely be ongoing across central/northern MO early Saturday as the nocturnal low-level jet persists into the early morning, supporting warm-air advection into the region. Given the abundance of antecedent precipitation, the expectation is for predominantly moist profiles with only modest instability. An isolated water-loaded downburst is possible. As the low-level jet diurnally weakens and the showers and thunderstorms gradually diminish across MO, additional showers and thunderstorms will likely be developing along the cold front as it moves through the western Dakotas early Saturday afternoon. Limited diurnal heating and less favorable low-level moisture should initially keep the severe threat isolated. Low-level moisture and resulting instability increase with eastern extent, suggesting higher severe thunderstorm coverage along the front as it moves into central SD and central NE during the late afternoon. As the front continues eastward during the evening, a nocturnal low-level jet is expected to develop from the southern Plains into the middle MS Valley. This should lead to an increase in showers and thunderstorms ahead of the front from eastern NE into northern MO, IA, and far northwest IL. Steep mid-level lapse rates and strong buoyancy will be in place and some of the initial development could pose a risk for severe hail. Additionally, as the storms along the front interact with these warm-air advection induced, storm mergers could lead to storm intensification and relatively higher severe probabilities. Hail and damaging wind gusts are the primary threats. ...Eastern CO and TX/OK Panhandles into eastern KS... A lee trough/dryline is expected to extend from the far western NE Panhandle southward through eastern CO and into the central TX/OK Panhandles. Large-scale forcing for ascent near this boundary will be negligible, except across northeast CO where modest large-scale ascent is possible from the shortwave trough farther north. Even so, isolated storms area possible along this boundary as temperatures climb into the upper 90s/low 100s and the boundary-layer mixes deeply. A strong wind gust or two with these high-based storms. Across eastern KS, remnant boundary from the antecedent MCS could provide the impetus for surface-based storms during the afternoon. However, despite ample low-level moisture, warm mid-level temperatures and the lack of stronger forcing for ascent cast doubt into storm initiation. If storms do develop, strong buoyancy and modest vertical shear would support supercells capable of all severe hazards, including very large hail and a tornado or two. ...Northeast OH across NY and into western New England... A low-amplitude shortwave trough is expected to move into western portions of the region during the early afternoon. Southwesterly low-level winds and heating will lead to around 1000 J/kg MUCAPE, with around 35-40 kt of effective shear. The approaching shortwave trough will provide the impetus for storm development beginning during the early afternoon from northern OH into western NY. While low-level shear will not be strong, effective SRH of 100-150 m2/s2 may support a brief supercell capable of damaging wind gusts and/or marginal hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 08/16/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Fri Aug 16 2019 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTH DAKOTA...NEBRASKA AND KANSAS EASTWARD INTO WESTERN ILLINOIS... ...SUMMARY... Severe storms are possible over parts of the northern and central Plains and upper Midwest on Saturday. A few strong storms are also possible from the Lower Great Lakes into western New England. ...Synopsis... A deep shortwave trough is expected to move eastward from the northern Rockies/northern High Plains through the northern Plains and into the Upper Midwest on Saturday. Progression of this system will help maintain the enhanced westerly flow aloft extending from the northern Rockies/eastern Great Basin eastward through the Great Lakes. In particular, strong mid-level flow attendant to the shortwave trough will move into the northern Plains Saturday afternoon and evening. Progression of this shortwave trough will also help push a cold front quickly through the northern Plains and Upper Midwest. Farther south, persistent westerly flow aloft will help maintain relatively cool mid-level temperatures and steep mid-level lapse rates atop a very warm and moist low-level air mass across the central Plains and mid MS Valley. ...Northern/Central Plains into the Middle MS Valley... Showers and thunderstorms will likely be ongoing across central/northern MO early Saturday as the nocturnal low-level jet persists into the early morning, supporting warm-air advection into the region. Given the abundance of antecedent precipitation, the expectation is for predominantly moist profiles with only modest instability. An isolated water-loaded downburst is possible. As the low-level jet diurnally weakens and the showers and thunderstorms gradually diminish across MO, additional showers and thunderstorms will likely be developing along the cold front as it moves through the western Dakotas early Saturday afternoon. Limited diurnal heating and less favorable low-level moisture should initially keep the severe threat isolated. Low-level moisture and resulting instability increase with eastern extent, suggesting higher severe thunderstorm coverage along the front as it moves into central SD and central NE during the late afternoon. As the front continues eastward during the evening, a nocturnal low-level jet is expected to develop from the southern Plains into the middle MS Valley. This should lead to an increase in showers and thunderstorms ahead of the front from eastern NE into northern MO, IA, and far northwest IL. Steep mid-level lapse rates and strong buoyancy will be in place and some of the initial development could pose a risk for severe hail. Additionally, as the storms along the front interact with these warm-air advection induced, storm mergers could lead to storm intensification and relatively higher severe probabilities. Hail and damaging wind gusts are the primary threats. ...Eastern CO and TX/OK Panhandles into eastern KS... A lee trough/dryline is expected to extend from the far western NE Panhandle southward through eastern CO and into the central TX/OK Panhandles. Large-scale forcing for ascent near this boundary will be negligible, except across northeast CO where modest large-scale ascent is possible from the shortwave trough farther north. Even so, isolated storms area possible along this boundary as temperatures climb into the upper 90s/low 100s and the boundary-layer mixes deeply. A strong wind gust or two with these high-based storms. Across eastern KS, remnant boundary from the antecedent MCS could provide the impetus for surface-based storms during the afternoon. However, despite ample low-level moisture, warm mid-level temperatures and the lack of stronger forcing for ascent cast doubt into storm initiation. If storms do develop, strong buoyancy and modest vertical shear would support supercells capable of all severe hazards, including very large hail and a tornado or two. ...Northeast OH across NY and into western New England... A low-amplitude shortwave trough is expected to move into western portions of the region during the early afternoon. Southwesterly low-level winds and heating will lead to around 1000 J/kg MUCAPE, with around 35-40 kt of effective shear. The approaching shortwave trough will provide the impetus for storm development beginning during the early afternoon from northern OH into western NY. While low-level shear will not be strong, effective SRH of 100-150 m2/s2 may support a brief supercell capable of damaging wind gusts and/or marginal hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 08/16/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Fri Aug 16 2019 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTH DAKOTA...NEBRASKA AND KANSAS EASTWARD INTO WESTERN ILLINOIS... ...SUMMARY... Severe storms are possible over parts of the northern and central Plains and upper Midwest on Saturday. A few strong storms are also possible from the Lower Great Lakes into western New England. ...Synopsis... A deep shortwave trough is expected to move eastward from the northern Rockies/northern High Plains through the northern Plains and into the Upper Midwest on Saturday. Progression of this system will help maintain the enhanced westerly flow aloft extending from the northern Rockies/eastern Great Basin eastward through the Great Lakes. In particular, strong mid-level flow attendant to the shortwave trough will move into the northern Plains Saturday afternoon and evening. Progression of this shortwave trough will also help push a cold front quickly through the northern Plains and Upper Midwest. Farther south, persistent westerly flow aloft will help maintain relatively cool mid-level temperatures and steep mid-level lapse rates atop a very warm and moist low-level air mass across the central Plains and mid MS Valley. ...Northern/Central Plains into the Middle MS Valley... Showers and thunderstorms will likely be ongoing across central/northern MO early Saturday as the nocturnal low-level jet persists into the early morning, supporting warm-air advection into the region. Given the abundance of antecedent precipitation, the expectation is for predominantly moist profiles with only modest instability. An isolated water-loaded downburst is possible. As the low-level jet diurnally weakens and the showers and thunderstorms gradually diminish across MO, additional showers and thunderstorms will likely be developing along the cold front as it moves through the western Dakotas early Saturday afternoon. Limited diurnal heating and less favorable low-level moisture should initially keep the severe threat isolated. Low-level moisture and resulting instability increase with eastern extent, suggesting higher severe thunderstorm coverage along the front as it moves into central SD and central NE during the late afternoon. As the front continues eastward during the evening, a nocturnal low-level jet is expected to develop from the southern Plains into the middle MS Valley. This should lead to an increase in showers and thunderstorms ahead of the front from eastern NE into northern MO, IA, and far northwest IL. Steep mid-level lapse rates and strong buoyancy will be in place and some of the initial development could pose a risk for severe hail. Additionally, as the storms along the front interact with these warm-air advection induced, storm mergers could lead to storm intensification and relatively higher severe probabilities. Hail and damaging wind gusts are the primary threats. ...Eastern CO and TX/OK Panhandles into eastern KS... A lee trough/dryline is expected to extend from the far western NE Panhandle southward through eastern CO and into the central TX/OK Panhandles. Large-scale forcing for ascent near this boundary will be negligible, except across northeast CO where modest large-scale ascent is possible from the shortwave trough farther north. Even so, isolated storms area possible along this boundary as temperatures climb into the upper 90s/low 100s and the boundary-layer mixes deeply. A strong wind gust or two with these high-based storms. Across eastern KS, remnant boundary from the antecedent MCS could provide the impetus for surface-based storms during the afternoon. However, despite ample low-level moisture, warm mid-level temperatures and the lack of stronger forcing for ascent cast doubt into storm initiation. If storms do develop, strong buoyancy and modest vertical shear would support supercells capable of all severe hazards, including very large hail and a tornado or two. ...Northeast OH across NY and into western New England... A low-amplitude shortwave trough is expected to move into western portions of the region during the early afternoon. Southwesterly low-level winds and heating will lead to around 1000 J/kg MUCAPE, with around 35-40 kt of effective shear. The approaching shortwave trough will provide the impetus for storm development beginning during the early afternoon from northern OH into western NY. While low-level shear will not be strong, effective SRH of 100-150 m2/s2 may support a brief supercell capable of damaging wind gusts and/or marginal hail. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 15% - Slight ..Mosier.. 08/16/2019 Read more

MD 1759 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NY INTO CENTRAL AND EASTERN PA AND ADJACENT PORTIONS OF NJ AND MD
Mesoscale Discussion 1759 NWS Storm Prediction Center Norman OK 1228 PM CDT Fri Aug 16 2019 Areas affected...portions of NY into central and eastern PA and adjacent portions of NJ and MD Concerning...Severe potential...Watch unlikely Valid 161728Z - 161930Z Probability of Watch Issuance...5 percent SUMMARY...A few strong wind gusts are possible across the region through the afternoon. The overall threat will remain isolated, and a watch is not expected. DISCUSSION...Widely scattered showers were quickly intensifying early this afternoon as temperatures warm into the mid 70s to low 80s across the region. Surface dewpoints range from the mid 60s to low 70s, resulting in modest destabilization with MLCAPE around 1000 J/kg currently. Convection should continue to increase in fast mid/upper level westerly flow as a shortwave trough spreads eastward across the Great Lakes. Poor midlevel lapse rates and weak low level flow will limit storm intensity, though effective shear around 30 kt should be adequate for some organized cells. As low level lapse rates continue to steepen, strongest storms could produce strong gusts capable of downing trees and other minor damage. Overall threat will remain rather transient/isolated and wane with loss of daytime heating, precluding the need for a severe thunderstorm watch. ..Leitman/Grams.. 08/16/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OKX...ALY...PHI...BGM...BUF...CTP...LWX... LAT...LON 43767620 43867544 43607426 43227387 42337371 41567388 39427619 39807759 41447784 42677800 43157762 43767620 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Aug 16 2019 Valid 161700Z - 171200Z The elevated area has been expanded somewhat to include mountain valleys across central CO where elevated to locally critical conditions are possible, and also to include a portion of the I-25 corridor where westerly downslope flow will develop very late this afternoon. Otherwise, forecast reasoning is unchanged from the previous outlook. Isolated mostly dry thunderstorms still appear possible from northeast UT into northwest CO and southern WY. See the previous discussion below for more details. ..Dean.. 08/16/2019 .PREV DISCUSSION... /ISSUED 0131 AM CDT Fri Aug 16 2019/ ...Synopsis... Broad upper-level troughing will continue across much of the northern half of the CONUS with multiple shortwave troughs moving across the country. One of these shortwave troughs will move over the central Rockies and central Plains with a mid-level jet of 40-50 knots extending west-east from northern Utah into southeast Wyoming and northeast Colorado. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) are likely to develop across eastern Utah, western/northern Colorado, and southern Wyoming this afternoon/evening. Locally critical conditions are likely to develop with the Upper Colorado River Valley, especially the Grand Valley, favored for these conditions to develop. Locally elevated conditions may develop across portions of the I-25 corridor as well where westerly downslope flow overtakes easterly upslope flow. Steepening mid-level lapse rates (7-8 C/km) with enough mid-level moisture (precipitable water of 0.5-0.6 inches) should result in isolated dry thunderstorms in portions of northwest Colorado and southern Wyoming this afternoon/evening. Daytime heating will help drive thermal-terrain circulations to create a mature Cu field tomorrow and forcing for ascent associated with the mid-level shortwave/jet should help isolated dry thunderstorms develop. Given the forecast dry/windy surface conditions, widespread wetting rains are unlikely. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Aug 16 2019 Valid 161700Z - 171200Z The elevated area has been expanded somewhat to include mountain valleys across central CO where elevated to locally critical conditions are possible, and also to include a portion of the I-25 corridor where westerly downslope flow will develop very late this afternoon. Otherwise, forecast reasoning is unchanged from the previous outlook. Isolated mostly dry thunderstorms still appear possible from northeast UT into northwest CO and southern WY. See the previous discussion below for more details. ..Dean.. 08/16/2019 .PREV DISCUSSION... /ISSUED 0131 AM CDT Fri Aug 16 2019/ ...Synopsis... Broad upper-level troughing will continue across much of the northern half of the CONUS with multiple shortwave troughs moving across the country. One of these shortwave troughs will move over the central Rockies and central Plains with a mid-level jet of 40-50 knots extending west-east from northern Utah into southeast Wyoming and northeast Colorado. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) are likely to develop across eastern Utah, western/northern Colorado, and southern Wyoming this afternoon/evening. Locally critical conditions are likely to develop with the Upper Colorado River Valley, especially the Grand Valley, favored for these conditions to develop. Locally elevated conditions may develop across portions of the I-25 corridor as well where westerly downslope flow overtakes easterly upslope flow. Steepening mid-level lapse rates (7-8 C/km) with enough mid-level moisture (precipitable water of 0.5-0.6 inches) should result in isolated dry thunderstorms in portions of northwest Colorado and southern Wyoming this afternoon/evening. Daytime heating will help drive thermal-terrain circulations to create a mature Cu field tomorrow and forcing for ascent associated with the mid-level shortwave/jet should help isolated dry thunderstorms develop. Given the forecast dry/windy surface conditions, widespread wetting rains are unlikely. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Aug 16 2019 Valid 161700Z - 171200Z The elevated area has been expanded somewhat to include mountain valleys across central CO where elevated to locally critical conditions are possible, and also to include a portion of the I-25 corridor where westerly downslope flow will develop very late this afternoon. Otherwise, forecast reasoning is unchanged from the previous outlook. Isolated mostly dry thunderstorms still appear possible from northeast UT into northwest CO and southern WY. See the previous discussion below for more details. ..Dean.. 08/16/2019 .PREV DISCUSSION... /ISSUED 0131 AM CDT Fri Aug 16 2019/ ...Synopsis... Broad upper-level troughing will continue across much of the northern half of the CONUS with multiple shortwave troughs moving across the country. One of these shortwave troughs will move over the central Rockies and central Plains with a mid-level jet of 40-50 knots extending west-east from northern Utah into southeast Wyoming and northeast Colorado. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) are likely to develop across eastern Utah, western/northern Colorado, and southern Wyoming this afternoon/evening. Locally critical conditions are likely to develop with the Upper Colorado River Valley, especially the Grand Valley, favored for these conditions to develop. Locally elevated conditions may develop across portions of the I-25 corridor as well where westerly downslope flow overtakes easterly upslope flow. Steepening mid-level lapse rates (7-8 C/km) with enough mid-level moisture (precipitable water of 0.5-0.6 inches) should result in isolated dry thunderstorms in portions of northwest Colorado and southern Wyoming this afternoon/evening. Daytime heating will help drive thermal-terrain circulations to create a mature Cu field tomorrow and forcing for ascent associated with the mid-level shortwave/jet should help isolated dry thunderstorms develop. Given the forecast dry/windy surface conditions, widespread wetting rains are unlikely. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Aug 16 2019 Valid 161700Z - 171200Z The elevated area has been expanded somewhat to include mountain valleys across central CO where elevated to locally critical conditions are possible, and also to include a portion of the I-25 corridor where westerly downslope flow will develop very late this afternoon. Otherwise, forecast reasoning is unchanged from the previous outlook. Isolated mostly dry thunderstorms still appear possible from northeast UT into northwest CO and southern WY. See the previous discussion below for more details. ..Dean.. 08/16/2019 .PREV DISCUSSION... /ISSUED 0131 AM CDT Fri Aug 16 2019/ ...Synopsis... Broad upper-level troughing will continue across much of the northern half of the CONUS with multiple shortwave troughs moving across the country. One of these shortwave troughs will move over the central Rockies and central Plains with a mid-level jet of 40-50 knots extending west-east from northern Utah into southeast Wyoming and northeast Colorado. Elevated conditions (westerly sustained surface winds of 15-20 mph, RH values of 10-20%) are likely to develop across eastern Utah, western/northern Colorado, and southern Wyoming this afternoon/evening. Locally critical conditions are likely to develop with the Upper Colorado River Valley, especially the Grand Valley, favored for these conditions to develop. Locally elevated conditions may develop across portions of the I-25 corridor as well where westerly downslope flow overtakes easterly upslope flow. Steepening mid-level lapse rates (7-8 C/km) with enough mid-level moisture (precipitable water of 0.5-0.6 inches) should result in isolated dry thunderstorms in portions of northwest Colorado and southern Wyoming this afternoon/evening. Daytime heating will help drive thermal-terrain circulations to create a mature Cu field tomorrow and forcing for ascent associated with the mid-level shortwave/jet should help isolated dry thunderstorms develop. Given the forecast dry/windy surface conditions, widespread wetting rains are unlikely. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Aug 16 2019 Valid 161630Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF EASTERN KS AND WESTERN MO... ...SUMMARY... Scattered severe storms are expected from the central High Plains to the Lower Missouri Valley with very large hail and damaging winds as the primary threats. The central High Plains threat will increase by late afternoon and spread across Kansas through the night, with the Missouri portion beginning this evening and continuing through the night. ...Central High Plains to the Lower MO Valley... While outflow from morning convection has spread across the Ozarks and northern OK, this should dissipate as convection further decays with a period of weakened low-level warm advection this afternoon. Primary surface front should become established by early evening from east-central CO arcing across southern KS through central MO as pronounced differential heating occurs across it. Warm 700-mb temperatures of 12-16 C within an intensifying and expanding stout elevated mixed layer, characterized by extremely steep 700-500 mb lapse rates of 9-9.5 C/km, will overspread much of the baroclinic zone and effectively cap surface-based storm development through early evening east of the high terrain. Initial storms should form near the Front Range within a weak low-level upslope flow regime north of the front, likely focused across northeast CO where more robust insolation is underway south of morning stratus. The western extent of upper 50s to low 60s surface dew points will coincide with the western periphery of MLCAPE exceeding 2000 J/kg. On the southern periphery of a strong mid-level jet centered on southeast WY to IA, a few supercells should develop with primary risks of very large hail and severe wind gusts. How this convection evolves through the evening and eastward into the northwest/north-central KS vicinity is uncertain given pronounced MLCIN. It is plausible that a sufficient cold pool might develop with colliding outflows and a subsequent MCS could expand/intensify eastward given broad strengthening of a southerly low-level jet across the frontal zone. With the presence of extreme mid-level lapse rates and strong to extreme buoyancy remaining centered across eastern KS, potential exists for a swath of significant severe wind and large hail continuing into early morning. Farther east across the Lower MO Valley, a separate zone of low-level warm-advection driven convection should develop near dusk and likely be regenerative through the night along the periphery of stronger MLCIN. Initial updrafts should have the greatest potential to produce significant severe hail. Convective mode should quickly evolve into potentially multiple clusters that would have a mixed risk of severe wind/hail given the ample buoyancy. The potential upstream MCS across northern KS might eventually merge with these clusters prior to dawn. ...Northeast to Great Lakes... A low-amplitude upper trough crossing the Lower Great Lakes to the Saint Lawrence Valley will foster scattered thunderstorm development along and ahead of its attendant surface trough. Modest mid-level lapse rates and weak lower-level flow will be limiting factors to a greater severe threat. Mid to upper-level speed shear will support small hail while a mixed boundary-layer yields potential for locally damaging winds. Overall threat should be more subdued compared to yesterday. A separate corridor of marginal severe potential is also apparent across eastern WI to western Lower MI along a cold front associated with a low-amplitude shortwave trough shifting east from northwest WI. ..Grams/Jirak.. 08/16/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Aug 16 2019 Valid 161630Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF EASTERN KS AND WESTERN MO... ...SUMMARY... Scattered severe storms are expected from the central High Plains to the Lower Missouri Valley with very large hail and damaging winds as the primary threats. The central High Plains threat will increase by late afternoon and spread across Kansas through the night, with the Missouri portion beginning this evening and continuing through the night. ...Central High Plains to the Lower MO Valley... While outflow from morning convection has spread across the Ozarks and northern OK, this should dissipate as convection further decays with a period of weakened low-level warm advection this afternoon. Primary surface front should become established by early evening from east-central CO arcing across southern KS through central MO as pronounced differential heating occurs across it. Warm 700-mb temperatures of 12-16 C within an intensifying and expanding stout elevated mixed layer, characterized by extremely steep 700-500 mb lapse rates of 9-9.5 C/km, will overspread much of the baroclinic zone and effectively cap surface-based storm development through early evening east of the high terrain. Initial storms should form near the Front Range within a weak low-level upslope flow regime north of the front, likely focused across northeast CO where more robust insolation is underway south of morning stratus. The western extent of upper 50s to low 60s surface dew points will coincide with the western periphery of MLCAPE exceeding 2000 J/kg. On the southern periphery of a strong mid-level jet centered on southeast WY to IA, a few supercells should develop with primary risks of very large hail and severe wind gusts. How this convection evolves through the evening and eastward into the northwest/north-central KS vicinity is uncertain given pronounced MLCIN. It is plausible that a sufficient cold pool might develop with colliding outflows and a subsequent MCS could expand/intensify eastward given broad strengthening of a southerly low-level jet across the frontal zone. With the presence of extreme mid-level lapse rates and strong to extreme buoyancy remaining centered across eastern KS, potential exists for a swath of significant severe wind and large hail continuing into early morning. Farther east across the Lower MO Valley, a separate zone of low-level warm-advection driven convection should develop near dusk and likely be regenerative through the night along the periphery of stronger MLCIN. Initial updrafts should have the greatest potential to produce significant severe hail. Convective mode should quickly evolve into potentially multiple clusters that would have a mixed risk of severe wind/hail given the ample buoyancy. The potential upstream MCS across northern KS might eventually merge with these clusters prior to dawn. ...Northeast to Great Lakes... A low-amplitude upper trough crossing the Lower Great Lakes to the Saint Lawrence Valley will foster scattered thunderstorm development along and ahead of its attendant surface trough. Modest mid-level lapse rates and weak lower-level flow will be limiting factors to a greater severe threat. Mid to upper-level speed shear will support small hail while a mixed boundary-layer yields potential for locally damaging winds. Overall threat should be more subdued compared to yesterday. A separate corridor of marginal severe potential is also apparent across eastern WI to western Lower MI along a cold front associated with a low-amplitude shortwave trough shifting east from northwest WI. ..Grams/Jirak.. 08/16/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Aug 16 2019 Valid 161630Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF EASTERN KS AND WESTERN MO... ...SUMMARY... Scattered severe storms are expected from the central High Plains to the Lower Missouri Valley with very large hail and damaging winds as the primary threats. The central High Plains threat will increase by late afternoon and spread across Kansas through the night, with the Missouri portion beginning this evening and continuing through the night. ...Central High Plains to the Lower MO Valley... While outflow from morning convection has spread across the Ozarks and northern OK, this should dissipate as convection further decays with a period of weakened low-level warm advection this afternoon. Primary surface front should become established by early evening from east-central CO arcing across southern KS through central MO as pronounced differential heating occurs across it. Warm 700-mb temperatures of 12-16 C within an intensifying and expanding stout elevated mixed layer, characterized by extremely steep 700-500 mb lapse rates of 9-9.5 C/km, will overspread much of the baroclinic zone and effectively cap surface-based storm development through early evening east of the high terrain. Initial storms should form near the Front Range within a weak low-level upslope flow regime north of the front, likely focused across northeast CO where more robust insolation is underway south of morning stratus. The western extent of upper 50s to low 60s surface dew points will coincide with the western periphery of MLCAPE exceeding 2000 J/kg. On the southern periphery of a strong mid-level jet centered on southeast WY to IA, a few supercells should develop with primary risks of very large hail and severe wind gusts. How this convection evolves through the evening and eastward into the northwest/north-central KS vicinity is uncertain given pronounced MLCIN. It is plausible that a sufficient cold pool might develop with colliding outflows and a subsequent MCS could expand/intensify eastward given broad strengthening of a southerly low-level jet across the frontal zone. With the presence of extreme mid-level lapse rates and strong to extreme buoyancy remaining centered across eastern KS, potential exists for a swath of significant severe wind and large hail continuing into early morning. Farther east across the Lower MO Valley, a separate zone of low-level warm-advection driven convection should develop near dusk and likely be regenerative through the night along the periphery of stronger MLCIN. Initial updrafts should have the greatest potential to produce significant severe hail. Convective mode should quickly evolve into potentially multiple clusters that would have a mixed risk of severe wind/hail given the ample buoyancy. The potential upstream MCS across northern KS might eventually merge with these clusters prior to dawn. ...Northeast to Great Lakes... A low-amplitude upper trough crossing the Lower Great Lakes to the Saint Lawrence Valley will foster scattered thunderstorm development along and ahead of its attendant surface trough. Modest mid-level lapse rates and weak lower-level flow will be limiting factors to a greater severe threat. Mid to upper-level speed shear will support small hail while a mixed boundary-layer yields potential for locally damaging winds. Overall threat should be more subdued compared to yesterday. A separate corridor of marginal severe potential is also apparent across eastern WI to western Lower MI along a cold front associated with a low-amplitude shortwave trough shifting east from northwest WI. ..Grams/Jirak.. 08/16/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Fri Aug 16 2019 Valid 161630Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF EASTERN KS AND WESTERN MO... ...SUMMARY... Scattered severe storms are expected from the central High Plains to the Lower Missouri Valley with very large hail and damaging winds as the primary threats. The central High Plains threat will increase by late afternoon and spread across Kansas through the night, with the Missouri portion beginning this evening and continuing through the night. ...Central High Plains to the Lower MO Valley... While outflow from morning convection has spread across the Ozarks and northern OK, this should dissipate as convection further decays with a period of weakened low-level warm advection this afternoon. Primary surface front should become established by early evening from east-central CO arcing across southern KS through central MO as pronounced differential heating occurs across it. Warm 700-mb temperatures of 12-16 C within an intensifying and expanding stout elevated mixed layer, characterized by extremely steep 700-500 mb lapse rates of 9-9.5 C/km, will overspread much of the baroclinic zone and effectively cap surface-based storm development through early evening east of the high terrain. Initial storms should form near the Front Range within a weak low-level upslope flow regime north of the front, likely focused across northeast CO where more robust insolation is underway south of morning stratus. The western extent of upper 50s to low 60s surface dew points will coincide with the western periphery of MLCAPE exceeding 2000 J/kg. On the southern periphery of a strong mid-level jet centered on southeast WY to IA, a few supercells should develop with primary risks of very large hail and severe wind gusts. How this convection evolves through the evening and eastward into the northwest/north-central KS vicinity is uncertain given pronounced MLCIN. It is plausible that a sufficient cold pool might develop with colliding outflows and a subsequent MCS could expand/intensify eastward given broad strengthening of a southerly low-level jet across the frontal zone. With the presence of extreme mid-level lapse rates and strong to extreme buoyancy remaining centered across eastern KS, potential exists for a swath of significant severe wind and large hail continuing into early morning. Farther east across the Lower MO Valley, a separate zone of low-level warm-advection driven convection should develop near dusk and likely be regenerative through the night along the periphery of stronger MLCIN. Initial updrafts should have the greatest potential to produce significant severe hail. Convective mode should quickly evolve into potentially multiple clusters that would have a mixed risk of severe wind/hail given the ample buoyancy. The potential upstream MCS across northern KS might eventually merge with these clusters prior to dawn. ...Northeast to Great Lakes... A low-amplitude upper trough crossing the Lower Great Lakes to the Saint Lawrence Valley will foster scattered thunderstorm development along and ahead of its attendant surface trough. Modest mid-level lapse rates and weak lower-level flow will be limiting factors to a greater severe threat. Mid to upper-level speed shear will support small hail while a mixed boundary-layer yields potential for locally damaging winds. Overall threat should be more subdued compared to yesterday. A separate corridor of marginal severe potential is also apparent across eastern WI to western Lower MI along a cold front associated with a low-amplitude shortwave trough shifting east from northwest WI. ..Grams/Jirak.. 08/16/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Fri Aug 16 2019 Valid 161300Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PARTS OF KANSAS AND MISSOURI... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe thunderstorms appears to be this evening and overnight, for hail and wind over portions of northeastern Kansas and western/central Missouri. ...Synopsis... In mid/upper levels, a set of cyclones across western and northern Canada, along with assorted shortwaves to their south, is contributing to a zonal to slightly cyclonic pattern across the northern half of the CONUS. A leading shortwave trough -- initially over New England, will eject away from the region. Meanwhile another perturbation -- apparent in moisture-channel imagery over parts of WI and northern IL -- should eject northeastward across Upper MI and eastern Lake Superior to adjoining parts of northeastern ON. A weak shortwave trough currently over OH will move east-northeastward across parts of PA and NY, weakening further through the period. Upstream, another perturbation is evident over southeastern MT and eastern WY, and should shift east-southeastward to near the OMA/FSD corridor by 00Z, then reaching Lower MI by 12Z. At the surface, 11Z analysis showed a weak surface low over eastern PA, with quasistationary frontal zone southwestward roughly down the Blue Ridge to north-central GA, then arching northwestward into an area of outflow over southeastern MO. That part of this front east of the Mississippi River should move little through the period. Another frontal zone -- weakly cold to stationary -- was drawn from central IA across central/southwestern KS. This boundary should move eastward across portions of WI and northern IL by 00Z, just ahead of the mid/upper trough, then eastward over Lower MI and much of IL by the end of the period, while the remainder of the front remains across parts of KS/MO. ...KS/MO and vicinity... Scattered to numerous thunderstorms in clusters should form this evening and overnight in and near the enhanced-risk area, offering large hail -- some significant/2+ inches being possible from any supercells. Damaging gusts also cannot be ruled out, though this threat is more conditional on location/extent of upscale cold-pool aggregation and depth/strength of near-surface static stability in the nocturnal preconvective environment. An extensive area of convective outflow is present at outlook time over much of MO and eastern KS, reinforced by multiple rounds of convection during the prior overnight period. Considerable uncertainty exists in the northeastward extent and timing of favorable air mass recovery by late afternoon and evening -- both surface and aloft over western/northern MO. This is related not just to the mesoscale and at least partly elevated nature of the putative low-level forcing, but also both synoptic and convection- allowing models' poor performance with duration/extent of ongoing convection from northeastern OK across the KS/MO border region. Still, the concern is more of location and timing of overnight severe rather than density/intensity. With strong low-level warm advection and moisture transport accompanying a 50-60-kt southwesterly LLJ tonight, expect one or two primary clusters to move eastward to east-southeastward over the region with severe potential lingering through much of the overnight part of the period. ...Central High Plains... Widely scattered to scattered thunderstorms will form this afternoon over some of the higher terrain just east of the eastern mountains in CO/WY, including the Palmer Divide and Cheyenne Ridge, as strong surface heating preferentially removes CINH on the elevated terrain. Additional, isolated to widely scattered convection may form elsewhere across the western parts of the outlook area. This should occur primarily driven by boundary-layer forcing, both thermodynamically and kinematically (weak convergence and upslope-lift areas north of the front), since mid/upper-level support is meager. Severe hail and gusts will be the main concerns, with localized severe concentrations in both coverage and magnitude where sustained supercells and/or bow echoes can develop. Moisture and buoyancy will increase eastward, as will MLCINH with lowering altitude, amidst steep midlevel lapse rates. An axis of 1500-3000 J/kg MLCAPE should develop from extreme eastern WY southeastward to extreme eastern CO, amidst 40-45 kt effective-shear magnitudes. The threat generally should diminish through mid/late evening as the foregoing boundary layer stabilizes, though isolated severe activity may persist to near 06Z. ...Northeast... Widely scattered thunderstorms should form from midday through this afternoon, in zones of weak boundary-layer convergence related to a surface trough and remnant frontal zone. Isolated gusts to severe limits may occur from the most intense cells, and subsevere gusts still may produce minor damage. Areas of sustained surface heating are expected today amidst patchy low and high clouds, and behind the initial shortwave trough. This, combined with favorable surface moisture (e.g., dewpoints increasing through the 60s to near 70 F with southward extent), will offset modest mid/upper-level lapse rates to eradicate MLCINH and produce favorable buoyancy for afternoon convective development. Weak lift ahead of the subtle shortwave trough also may contribute to a favorable convective environment. Forecast soundings suggest MLCAPE generally in the 500-1200 J/kg range. Meanwhile, mid/upper-level winds and deep shear will increase northward, leading to effective-shear magnitudes in the 30-40-kt range area-wide. Organized multicells and brief/marginal supercell behavior are possible. ..Edwards/Marsh.. 08/16/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Fri Aug 16 2019 Valid 161300Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PARTS OF KANSAS AND MISSOURI... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe thunderstorms appears to be this evening and overnight, for hail and wind over portions of northeastern Kansas and western/central Missouri. ...Synopsis... In mid/upper levels, a set of cyclones across western and northern Canada, along with assorted shortwaves to their south, is contributing to a zonal to slightly cyclonic pattern across the northern half of the CONUS. A leading shortwave trough -- initially over New England, will eject away from the region. Meanwhile another perturbation -- apparent in moisture-channel imagery over parts of WI and northern IL -- should eject northeastward across Upper MI and eastern Lake Superior to adjoining parts of northeastern ON. A weak shortwave trough currently over OH will move east-northeastward across parts of PA and NY, weakening further through the period. Upstream, another perturbation is evident over southeastern MT and eastern WY, and should shift east-southeastward to near the OMA/FSD corridor by 00Z, then reaching Lower MI by 12Z. At the surface, 11Z analysis showed a weak surface low over eastern PA, with quasistationary frontal zone southwestward roughly down the Blue Ridge to north-central GA, then arching northwestward into an area of outflow over southeastern MO. That part of this front east of the Mississippi River should move little through the period. Another frontal zone -- weakly cold to stationary -- was drawn from central IA across central/southwestern KS. This boundary should move eastward across portions of WI and northern IL by 00Z, just ahead of the mid/upper trough, then eastward over Lower MI and much of IL by the end of the period, while the remainder of the front remains across parts of KS/MO. ...KS/MO and vicinity... Scattered to numerous thunderstorms in clusters should form this evening and overnight in and near the enhanced-risk area, offering large hail -- some significant/2+ inches being possible from any supercells. Damaging gusts also cannot be ruled out, though this threat is more conditional on location/extent of upscale cold-pool aggregation and depth/strength of near-surface static stability in the nocturnal preconvective environment. An extensive area of convective outflow is present at outlook time over much of MO and eastern KS, reinforced by multiple rounds of convection during the prior overnight period. Considerable uncertainty exists in the northeastward extent and timing of favorable air mass recovery by late afternoon and evening -- both surface and aloft over western/northern MO. This is related not just to the mesoscale and at least partly elevated nature of the putative low-level forcing, but also both synoptic and convection- allowing models' poor performance with duration/extent of ongoing convection from northeastern OK across the KS/MO border region. Still, the concern is more of location and timing of overnight severe rather than density/intensity. With strong low-level warm advection and moisture transport accompanying a 50-60-kt southwesterly LLJ tonight, expect one or two primary clusters to move eastward to east-southeastward over the region with severe potential lingering through much of the overnight part of the period. ...Central High Plains... Widely scattered to scattered thunderstorms will form this afternoon over some of the higher terrain just east of the eastern mountains in CO/WY, including the Palmer Divide and Cheyenne Ridge, as strong surface heating preferentially removes CINH on the elevated terrain. Additional, isolated to widely scattered convection may form elsewhere across the western parts of the outlook area. This should occur primarily driven by boundary-layer forcing, both thermodynamically and kinematically (weak convergence and upslope-lift areas north of the front), since mid/upper-level support is meager. Severe hail and gusts will be the main concerns, with localized severe concentrations in both coverage and magnitude where sustained supercells and/or bow echoes can develop. Moisture and buoyancy will increase eastward, as will MLCINH with lowering altitude, amidst steep midlevel lapse rates. An axis of 1500-3000 J/kg MLCAPE should develop from extreme eastern WY southeastward to extreme eastern CO, amidst 40-45 kt effective-shear magnitudes. The threat generally should diminish through mid/late evening as the foregoing boundary layer stabilizes, though isolated severe activity may persist to near 06Z. ...Northeast... Widely scattered thunderstorms should form from midday through this afternoon, in zones of weak boundary-layer convergence related to a surface trough and remnant frontal zone. Isolated gusts to severe limits may occur from the most intense cells, and subsevere gusts still may produce minor damage. Areas of sustained surface heating are expected today amidst patchy low and high clouds, and behind the initial shortwave trough. This, combined with favorable surface moisture (e.g., dewpoints increasing through the 60s to near 70 F with southward extent), will offset modest mid/upper-level lapse rates to eradicate MLCINH and produce favorable buoyancy for afternoon convective development. Weak lift ahead of the subtle shortwave trough also may contribute to a favorable convective environment. Forecast soundings suggest MLCAPE generally in the 500-1200 J/kg range. Meanwhile, mid/upper-level winds and deep shear will increase northward, leading to effective-shear magnitudes in the 30-40-kt range area-wide. Organized multicells and brief/marginal supercell behavior are possible. ..Edwards/Marsh.. 08/16/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Fri Aug 16 2019 Valid 161300Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PARTS OF KANSAS AND MISSOURI... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... The greatest threat for severe thunderstorms appears to be this evening and overnight, for hail and wind over portions of northeastern Kansas and western/central Missouri. ...Synopsis... In mid/upper levels, a set of cyclones across western and northern Canada, along with assorted shortwaves to their south, is contributing to a zonal to slightly cyclonic pattern across the northern half of the CONUS. A leading shortwave trough -- initially over New England, will eject away from the region. Meanwhile another perturbation -- apparent in moisture-channel imagery over parts of WI and northern IL -- should eject northeastward across Upper MI and eastern Lake Superior to adjoining parts of northeastern ON. A weak shortwave trough currently over OH will move east-northeastward across parts of PA and NY, weakening further through the period. Upstream, another perturbation is evident over southeastern MT and eastern WY, and should shift east-southeastward to near the OMA/FSD corridor by 00Z, then reaching Lower MI by 12Z. At the surface, 11Z analysis showed a weak surface low over eastern PA, with quasistationary frontal zone southwestward roughly down the Blue Ridge to north-central GA, then arching northwestward into an area of outflow over southeastern MO. That part of this front east of the Mississippi River should move little through the period. Another frontal zone -- weakly cold to stationary -- was drawn from central IA across central/southwestern KS. This boundary should move eastward across portions of WI and northern IL by 00Z, just ahead of the mid/upper trough, then eastward over Lower MI and much of IL by the end of the period, while the remainder of the front remains across parts of KS/MO. ...KS/MO and vicinity... Scattered to numerous thunderstorms in clusters should form this evening and overnight in and near the enhanced-risk area, offering large hail -- some significant/2+ inches being possible from any supercells. Damaging gusts also cannot be ruled out, though this threat is more conditional on location/extent of upscale cold-pool aggregation and depth/strength of near-surface static stability in the nocturnal preconvective environment. An extensive area of convective outflow is present at outlook time over much of MO and eastern KS, reinforced by multiple rounds of convection during the prior overnight period. Considerable uncertainty exists in the northeastward extent and timing of favorable air mass recovery by late afternoon and evening -- both surface and aloft over western/northern MO. This is related not just to the mesoscale and at least partly elevated nature of the putative low-level forcing, but also both synoptic and convection- allowing models' poor performance with duration/extent of ongoing convection from northeastern OK across the KS/MO border region. Still, the concern is more of location and timing of overnight severe rather than density/intensity. With strong low-level warm advection and moisture transport accompanying a 50-60-kt southwesterly LLJ tonight, expect one or two primary clusters to move eastward to east-southeastward over the region with severe potential lingering through much of the overnight part of the period. ...Central High Plains... Widely scattered to scattered thunderstorms will form this afternoon over some of the higher terrain just east of the eastern mountains in CO/WY, including the Palmer Divide and Cheyenne Ridge, as strong surface heating preferentially removes CINH on the elevated terrain. Additional, isolated to widely scattered convection may form elsewhere across the western parts of the outlook area. This should occur primarily driven by boundary-layer forcing, both thermodynamically and kinematically (weak convergence and upslope-lift areas north of the front), since mid/upper-level support is meager. Severe hail and gusts will be the main concerns, with localized severe concentrations in both coverage and magnitude where sustained supercells and/or bow echoes can develop. Moisture and buoyancy will increase eastward, as will MLCINH with lowering altitude, amidst steep midlevel lapse rates. An axis of 1500-3000 J/kg MLCAPE should develop from extreme eastern WY southeastward to extreme eastern CO, amidst 40-45 kt effective-shear magnitudes. The threat generally should diminish through mid/late evening as the foregoing boundary layer stabilizes, though isolated severe activity may persist to near 06Z. ...Northeast... Widely scattered thunderstorms should form from midday through this afternoon, in zones of weak boundary-layer convergence related to a surface trough and remnant frontal zone. Isolated gusts to severe limits may occur from the most intense cells, and subsevere gusts still may produce minor damage. Areas of sustained surface heating are expected today amidst patchy low and high clouds, and behind the initial shortwave trough. This, combined with favorable surface moisture (e.g., dewpoints increasing through the 60s to near 70 F with southward extent), will offset modest mid/upper-level lapse rates to eradicate MLCINH and produce favorable buoyancy for afternoon convective development. Weak lift ahead of the subtle shortwave trough also may contribute to a favorable convective environment. Forecast soundings suggest MLCAPE generally in the 500-1200 J/kg range. Meanwhile, mid/upper-level winds and deep shear will increase northward, leading to effective-shear magnitudes in the 30-40-kt range area-wide. Organized multicells and brief/marginal supercell behavior are possible. ..Edwards/Marsh.. 08/16/2019 Read more

MD 1758 CONCERNING SEVERE THUNDERSTORM WATCH 587... FOR SOUTHEAST KANSAS AND WESTERN MISSOURI
Mesoscale Discussion 1758 NWS Storm Prediction Center Norman OK 0604 AM CDT Fri Aug 16 2019 Areas affected...southeast Kansas and western Missouri Concerning...Severe Thunderstorm Watch 587... Valid 161104Z - 161200Z The severe weather threat for Severe Thunderstorm Watch 587 continues. SUMMARY...Multiple areas of thunderstorms continue this morning all continue to exhibit a slow weakening trend. As such a new watch is currently not expected. DISCUSSION...Three distinct thunderstorm clusters are evident across the region this morning: 1) south-central Missouri -- the remnants of the original bow; 2)west-central Missouri -- the remnants of the initial warm-air advection storms; and 3)southeast Kansas -- newer warm-air advection storms. The remnants of the earlier bow echo continue to move east-southeast across south-central Missouri. The airmass along and ahead of this cluster should become increasingly hostile to thunderstorm maintenance, let alone severe maintenance. Most-unstable CAPE quickly drops off to near nothing to the east of the storms, and deep-layer shear decreases as well. Thus, the severe threat along and ahead of this cluster is low. The remnants of the initial warm-air advection storms across northeast Kansas have continued to slowly move east into western Missouri. Despite being fed from a moderately unstable airmass to the west, the persistent, slow-moving nature of the storms has likely stabilized the airmass in the immediate vicinity of the complex. This, combined with a weakening low-level jet, and subsequent decrease in warm-air advection later this morning, the overall severe threat should remain limited. Hail will be the primary severe threat. The newer warm-air advection thunderstorm development across southeast Kansas should continue for a few more hours. Here, the airmass is less worked over than areas farther north and east, suggesting a potential for severe hail. At the same time deep-layer shear is less, which would argue for less thunderstorm organization and less organized severe potential. Based on observed trends, some potential exists for a thunderstorm or two to briefly support hail in excess of 1 inch. However, the severe threat should remain poorly organized. All-in-all, while severe hail or wind cannot be ruled out anywhere within Severe Thunderstorm Watch #587, the overall severe threat is much less than earlier. Current expectations are that ongoing watch #587 will be allowed to expire at the top of the hour, with no plans for an additional watch. ..Marsh.. 08/16/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PAH...SGF...EAX...TSA...TOP...ICT... LAT...LON 36769631 39679430 36759107 36769631 Read more

WW 0587 Status Updates
STATUS REPORT ON WW 587 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 W CNU TO 35 NE CNU TO 20 WNW OJC TO 20 S FNB. ..MARSH..08/16/19 ATTN...WFO...ICT...TOP...EAX...SGF... STATUS REPORT FOR WS 587 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC001-005-011-021-037-091-099-103-107-121-133-205-209-161040- KS . KANSAS COUNTIES INCLUDED ARE ALLEN ATCHISON BOURBON CHEROKEE CRAWFORD JOHNSON LABETTE LEAVENWORTH LINN MIAMI NEOSHO WILSON WYANDOTTE MOC011-013-015-021-029-033-037-039-047-049-053-057-059-077-083- 085-095-097-101-105-107-109-131-141-159-165-167-169-177-185-195- 217-225-161040- MO . MISSOURI COUNTIES INCLUDED ARE BARTON BATES BENTON BUCHANAN CAMDEN CARROLL CASS CEDAR CLAY CLINTON COOPER DADE DALLAS GREENE HENRY HICKORY JACKSON JASPER Read more

WW 0587 Status Updates
STATUS REPORT ON WW 587 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 W CNU TO 35 NE CNU TO 20 WNW OJC TO 20 S FNB. ..MARSH..08/16/19 ATTN...WFO...ICT...TOP...EAX...SGF... STATUS REPORT FOR WS 587 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC001-005-011-021-037-091-099-103-107-121-133-205-209-161040- KS . KANSAS COUNTIES INCLUDED ARE ALLEN ATCHISON BOURBON CHEROKEE CRAWFORD JOHNSON LABETTE LEAVENWORTH LINN MIAMI NEOSHO WILSON WYANDOTTE MOC011-013-015-021-029-033-037-039-047-049-053-057-059-077-083- 085-095-097-101-105-107-109-131-141-159-165-167-169-177-185-195- 217-225-161040- MO . MISSOURI COUNTIES INCLUDED ARE BARTON BATES BENTON BUCHANAN CAMDEN CARROLL CASS CEDAR CLAY CLINTON COOPER DADE DALLAS GREENE HENRY HICKORY JACKSON JASPER Read more