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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Mon Aug 19 2019 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF IOWA TONIGHT... ...SUMMARY... The severe-thunderstorm threat appears most concentrated tonight over parts of Iowa, in the form of wind and hail. ...Synopsis... The broader mid/upper-level pattern over the CONUS is expected to amplify somewhat through tomorrow morning, as ridging builds from the southern High Plains across the central/northern Rockies. A synoptic cyclone over northern MB is progged to elongate zonally and redevelop eastward across southern Hudson Bay to northern QC through the period. As that occurs, general height rises are expected across most of the Great Lakes region. A related, positively tilted shortwave trough is located from western NY southwestward across the Tennessee Valley region. The southern portion of this trough, from KY southward, will move eastward and weaken considerably. The northern part will eject northeastward across the remainder of PA, NY and New England through about 00Z. A weak shortwave trough -- initially apparent in moisture-channel imagery over WY -- is forecast to move eastward across much of southern SD and northern NE through 00Z, then turn southeastward over IA overnight. At the surface, the 11Z analysis showed a cold front from southwestern QC across southern ON to southern/central Lower MI, becoming wavy and quasistationary southwestward across southeastern IA, northwestern MO, and central/western KS. The central Plains segment of this front is forecast to move northward and reorient from northwest to southeast through the period. By 12Z the resulting warm front should extend from east-central/northeastern WY across northern NE and western/southern IA. A dryline should mix eastward across the High Plains today, reaching the NE Panhandle, extreme eastern CO/western KS and northeastern NM. ...Northern Plains to IA... Isolated to widely scattered thunderstorms are expected to form over the northern Plains part of the outlook area this afternoon into evening, offering the potential for isolated severe gusts/hail. A more-robust severe threat is becoming apparent overnight across portions of IA in association with potential formation of severe thunderstorms with large hail as the main early-stage threat, evolving toward damaging wind as activity aggregates upscale. A forward-propagational MCS is possible into parts of central/southern IA late overnight. Return flow on either side of the warm-frontal zone will foster increasing low-level theta-e throughout the day and into tonight, with 60s surface dew points becoming common, and values near 70 F possible on an isolated basis. Large-scale support will be weak, especially with heights building over and west of the area, but weak MLCINH and strong surface heating should foster the development of at least a few thunderstorms in an environment of steep low/middle- level lapse rates and well-mixed subcloud layers. Increasing moisture with southward/southeastward extent and backing of low- level flow near and on the north side of the warm front will augment deep shear in support of some supercell potential with any sustained convection. MLCAPE 3000-4500 J/kg is possible. Lack of stronger large-scale support, and concerns over convective coverage, preclude more than a marginal risk for most of the region at this time. However, concerns (and prognostic consensus) for overnight MCS action are increasing across portions of IA in the zone of strong low-level warm advection and moisture transport, near the nose of a 40-50-kt southwesterly LLJ. Steep midlevel lapse rates and increasing low-level moisture will yield MUCAPE increasing to the 2500-3500 J/kg range with decreasing MUCINH. While forecast soundings depict parcels rooted in the low levels, but above the surface, the presence of dry air in the subcloud layer suggests the potential for strong-severe downdrafts to reach the surface -- especially with support from any cold-pool forcing and rear-inflow- jet processes that can organize on the storm scale. Effective-shear magnitudes in the 35-50-kt range also indicate the potential for supercells, especially in the early hours of convective organization before too much clustering occurs, and an attendant severe-hail threat. ...New England... Widely scattered thunderstorms are expected to form as early as midday over portions of central/northern NY and during the afternoon elsewhere, in a loosely north-northeast/south-southwest-oriented broken band. Damaging gusts, including isolated gusts to severe limits, are possible region-wide. A marginal hail threat exists mainly over ME, and a tornado cannot be ruled out. Activity should develop behind and between areas of antecedent cloud cover, near a surface trough, where diabatic surface heating can destabilize the boundary layer favorably and remove MLCINH. Weak large-scale ascent also should spread across the area very near the ejecting mid/upper-level shortwave trough. These factors, along with moisture represented by surface dew points generally in the mid/upper 60s F, should support the development of preconvective afternoon MLCAPE in the 1000-1500 J/kg range. Mid/upper-level winds will strengthen with northward extent across the outlook area, and with time through afternoon over northern New England, as the aforementioned cyclonic processes over Canada tighten the height gradient aloft. Though low-level hodograph size will be modest, effective-shear magnitudes of 30-40 kt may favor organized multicells, small bows, and transient/marginal supercellular characteristics especially in ME. ...Central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon near the dryline and move eastward to northeastward. Very strong heating/mixing of the boundary layer is forecast, which will yield nearly dry-adiabatic lapse rates from surface to near 500 mb. Modified model soundings yield around 500-1000 J/kg MLCAPE in those areas east of the dryline/lee trough where CINH is minimized. CAPE increases with eastward extent into more robust moisture, but so will capping. Lack of more robust low/middle-level winds will limit vertical shear, but the well-mixed subcloud layer will support isolated severe downburst potential with any sustained convection. ..Edwards/Marsh.. 08/19/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Mon Aug 19 2019 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF IOWA TONIGHT... ...SUMMARY... The severe-thunderstorm threat appears most concentrated tonight over parts of Iowa, in the form of wind and hail. ...Synopsis... The broader mid/upper-level pattern over the CONUS is expected to amplify somewhat through tomorrow morning, as ridging builds from the southern High Plains across the central/northern Rockies. A synoptic cyclone over northern MB is progged to elongate zonally and redevelop eastward across southern Hudson Bay to northern QC through the period. As that occurs, general height rises are expected across most of the Great Lakes region. A related, positively tilted shortwave trough is located from western NY southwestward across the Tennessee Valley region. The southern portion of this trough, from KY southward, will move eastward and weaken considerably. The northern part will eject northeastward across the remainder of PA, NY and New England through about 00Z. A weak shortwave trough -- initially apparent in moisture-channel imagery over WY -- is forecast to move eastward across much of southern SD and northern NE through 00Z, then turn southeastward over IA overnight. At the surface, the 11Z analysis showed a cold front from southwestern QC across southern ON to southern/central Lower MI, becoming wavy and quasistationary southwestward across southeastern IA, northwestern MO, and central/western KS. The central Plains segment of this front is forecast to move northward and reorient from northwest to southeast through the period. By 12Z the resulting warm front should extend from east-central/northeastern WY across northern NE and western/southern IA. A dryline should mix eastward across the High Plains today, reaching the NE Panhandle, extreme eastern CO/western KS and northeastern NM. ...Northern Plains to IA... Isolated to widely scattered thunderstorms are expected to form over the northern Plains part of the outlook area this afternoon into evening, offering the potential for isolated severe gusts/hail. A more-robust severe threat is becoming apparent overnight across portions of IA in association with potential formation of severe thunderstorms with large hail as the main early-stage threat, evolving toward damaging wind as activity aggregates upscale. A forward-propagational MCS is possible into parts of central/southern IA late overnight. Return flow on either side of the warm-frontal zone will foster increasing low-level theta-e throughout the day and into tonight, with 60s surface dew points becoming common, and values near 70 F possible on an isolated basis. Large-scale support will be weak, especially with heights building over and west of the area, but weak MLCINH and strong surface heating should foster the development of at least a few thunderstorms in an environment of steep low/middle- level lapse rates and well-mixed subcloud layers. Increasing moisture with southward/southeastward extent and backing of low- level flow near and on the north side of the warm front will augment deep shear in support of some supercell potential with any sustained convection. MLCAPE 3000-4500 J/kg is possible. Lack of stronger large-scale support, and concerns over convective coverage, preclude more than a marginal risk for most of the region at this time. However, concerns (and prognostic consensus) for overnight MCS action are increasing across portions of IA in the zone of strong low-level warm advection and moisture transport, near the nose of a 40-50-kt southwesterly LLJ. Steep midlevel lapse rates and increasing low-level moisture will yield MUCAPE increasing to the 2500-3500 J/kg range with decreasing MUCINH. While forecast soundings depict parcels rooted in the low levels, but above the surface, the presence of dry air in the subcloud layer suggests the potential for strong-severe downdrafts to reach the surface -- especially with support from any cold-pool forcing and rear-inflow- jet processes that can organize on the storm scale. Effective-shear magnitudes in the 35-50-kt range also indicate the potential for supercells, especially in the early hours of convective organization before too much clustering occurs, and an attendant severe-hail threat. ...New England... Widely scattered thunderstorms are expected to form as early as midday over portions of central/northern NY and during the afternoon elsewhere, in a loosely north-northeast/south-southwest-oriented broken band. Damaging gusts, including isolated gusts to severe limits, are possible region-wide. A marginal hail threat exists mainly over ME, and a tornado cannot be ruled out. Activity should develop behind and between areas of antecedent cloud cover, near a surface trough, where diabatic surface heating can destabilize the boundary layer favorably and remove MLCINH. Weak large-scale ascent also should spread across the area very near the ejecting mid/upper-level shortwave trough. These factors, along with moisture represented by surface dew points generally in the mid/upper 60s F, should support the development of preconvective afternoon MLCAPE in the 1000-1500 J/kg range. Mid/upper-level winds will strengthen with northward extent across the outlook area, and with time through afternoon over northern New England, as the aforementioned cyclonic processes over Canada tighten the height gradient aloft. Though low-level hodograph size will be modest, effective-shear magnitudes of 30-40 kt may favor organized multicells, small bows, and transient/marginal supercellular characteristics especially in ME. ...Central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon near the dryline and move eastward to northeastward. Very strong heating/mixing of the boundary layer is forecast, which will yield nearly dry-adiabatic lapse rates from surface to near 500 mb. Modified model soundings yield around 500-1000 J/kg MLCAPE in those areas east of the dryline/lee trough where CINH is minimized. CAPE increases with eastward extent into more robust moisture, but so will capping. Lack of more robust low/middle-level winds will limit vertical shear, but the well-mixed subcloud layer will support isolated severe downburst potential with any sustained convection. ..Edwards/Marsh.. 08/19/2019 Read more

000
ABPZ20 KNHC 191149
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Mon Aug 19 2019

For the eastern North Pacific...east of 140 degrees west longitude:

An elongated area of low pressure located a couple of hundred miles
southeast of the Gulf of Tehuantepec is producing disorganized
showers and thunderstorms. Environmental conditions are
forecast to become conducive for development during the next
couple of days, and a tropical depression is likely to form by
mid-week while the low moves west-northwestward at about
10 mph parallel to the coast of Mexico. Moisture associated with
this disturbance could produce heavy rainfall and possible flash
flooding across portions of Guatemala and southeastern Mexico during
the next couple of days.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...90 percent.

A well-defined low pressure system located more 900 miles southwest
of the southern tip of the Baja California peninsula continues to
produce a large area of cloudiness and thunderstorms. Environmental
conditions are expected to gradually become more conducive for
development, and a tropical depression is likely to form during the
next few days while the system moves westward to west-northwestward
at about 10 mph.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Roberts

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Mon Aug 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Thursday/D4, a vertically stacked low will develop over southern Quebec with strong southwest winds aloft overspreading the northeastern states. A cold front will rapidly move across New England and will trail southward toward the Delmarva, though models differ in timing. MUCAPE on the order of 1000 J/kg is expected over northern areas ahead of the front, with greater values approaching 2000 J/kg into NJ and eastern VA where dewpoints will be in the 70s F. Shear will be less over southern areas, but still sufficient to support at least a marginal wind and hail threat. Long hodographs will favor cells or fast-moving line segments over northern areas, but there is more model discrepancy regarding speed of the cold front. If the more progressive model solutions are correct, there may be little opportunity for severe storms north of Long Island. As such, will defer possible upgrades to later outlooks. To the west, a lesser shortwave trough will move across the northern Rockies and Plains during the Thursday/D4 to Friday/D5 period, though models vary greatly with the strength of this feature. Regardless, southeast surface winds may result in enough moisture advection into the northern Plains for at least a marginal severe risk along an attendant cold front. For the Saturday/D6 to Monday/D8 period, a relatively strong upper jet is forecast to nose into the northern Rockies and Plains, then eventually into the upper MS Valley. Increasing shear and lift will likely interact with increasing low-level moisture and instability over the Dakotas, MN, NE and IA. Predictability is low for this time frame, but probabilities could be added in future outlooks. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Mon Aug 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Thursday/D4, a vertically stacked low will develop over southern Quebec with strong southwest winds aloft overspreading the northeastern states. A cold front will rapidly move across New England and will trail southward toward the Delmarva, though models differ in timing. MUCAPE on the order of 1000 J/kg is expected over northern areas ahead of the front, with greater values approaching 2000 J/kg into NJ and eastern VA where dewpoints will be in the 70s F. Shear will be less over southern areas, but still sufficient to support at least a marginal wind and hail threat. Long hodographs will favor cells or fast-moving line segments over northern areas, but there is more model discrepancy regarding speed of the cold front. If the more progressive model solutions are correct, there may be little opportunity for severe storms north of Long Island. As such, will defer possible upgrades to later outlooks. To the west, a lesser shortwave trough will move across the northern Rockies and Plains during the Thursday/D4 to Friday/D5 period, though models vary greatly with the strength of this feature. Regardless, southeast surface winds may result in enough moisture advection into the northern Plains for at least a marginal severe risk along an attendant cold front. For the Saturday/D6 to Monday/D8 period, a relatively strong upper jet is forecast to nose into the northern Rockies and Plains, then eventually into the upper MS Valley. Increasing shear and lift will likely interact with increasing low-level moisture and instability over the Dakotas, MN, NE and IA. Predictability is low for this time frame, but probabilities could be added in future outlooks. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Mon Aug 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Thursday/D4, a vertically stacked low will develop over southern Quebec with strong southwest winds aloft overspreading the northeastern states. A cold front will rapidly move across New England and will trail southward toward the Delmarva, though models differ in timing. MUCAPE on the order of 1000 J/kg is expected over northern areas ahead of the front, with greater values approaching 2000 J/kg into NJ and eastern VA where dewpoints will be in the 70s F. Shear will be less over southern areas, but still sufficient to support at least a marginal wind and hail threat. Long hodographs will favor cells or fast-moving line segments over northern areas, but there is more model discrepancy regarding speed of the cold front. If the more progressive model solutions are correct, there may be little opportunity for severe storms north of Long Island. As such, will defer possible upgrades to later outlooks. To the west, a lesser shortwave trough will move across the northern Rockies and Plains during the Thursday/D4 to Friday/D5 period, though models vary greatly with the strength of this feature. Regardless, southeast surface winds may result in enough moisture advection into the northern Plains for at least a marginal severe risk along an attendant cold front. For the Saturday/D6 to Monday/D8 period, a relatively strong upper jet is forecast to nose into the northern Rockies and Plains, then eventually into the upper MS Valley. Increasing shear and lift will likely interact with increasing low-level moisture and instability over the Dakotas, MN, NE and IA. Predictability is low for this time frame, but probabilities could be added in future outlooks. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0333 AM CDT Mon Aug 19 2019 Valid 221200Z - 271200Z ...DISCUSSION... On Thursday/D4, a vertically stacked low will develop over southern Quebec with strong southwest winds aloft overspreading the northeastern states. A cold front will rapidly move across New England and will trail southward toward the Delmarva, though models differ in timing. MUCAPE on the order of 1000 J/kg is expected over northern areas ahead of the front, with greater values approaching 2000 J/kg into NJ and eastern VA where dewpoints will be in the 70s F. Shear will be less over southern areas, but still sufficient to support at least a marginal wind and hail threat. Long hodographs will favor cells or fast-moving line segments over northern areas, but there is more model discrepancy regarding speed of the cold front. If the more progressive model solutions are correct, there may be little opportunity for severe storms north of Long Island. As such, will defer possible upgrades to later outlooks. To the west, a lesser shortwave trough will move across the northern Rockies and Plains during the Thursday/D4 to Friday/D5 period, though models vary greatly with the strength of this feature. Regardless, southeast surface winds may result in enough moisture advection into the northern Plains for at least a marginal severe risk along an attendant cold front. For the Saturday/D6 to Monday/D8 period, a relatively strong upper jet is forecast to nose into the northern Rockies and Plains, then eventually into the upper MS Valley. Increasing shear and lift will likely interact with increasing low-level moisture and instability over the Dakotas, MN, NE and IA. Predictability is low for this time frame, but probabilities could be added in future outlooks. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Mon Aug 19 2019 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST...AND ACROSS THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... At least isolated severe storms are possible over parts of the Northeast, and from the central High Plains to the lower Missouri Valley. ...Synopsis... An upper low will move from James Bay into Quebec, with a leading shortwave trough developing east across the Great Lakes. Winds aloft will increase through the period over the northeastern states, with around 35 kt at 500 mb by late afternoon. Southerly surface winds will bring mid to upper 60s F dewpoints northward into southern New England as low pressure deepens over southern Quebec which will result in sufficient instability for strong to severe storms. To the west, an upper ridge will weaken as it moves from the Rockies into the Plains, with an upper trough moving across the Pacific Northwest. High pressure will exist over the northern Plains but surface winds will back over the northern High Plains resulting in westward moisture advection. To the southeast, the front will continue to progress southward across IA, IL and northern MO, with strong instability developing once again ahead of it. ...Northeast... Southwesterly low-level winds will maintain moisture advection across the region, which will increase instability but also result in areas of early day precipitation, as a warm front lifts north over New England. Meanwhile, shear will become more favorable for severe storms throughout the period as the upper trough approaches from the west. Forecast soundings indicate perhaps 1500 J/kg MUCAPE developing from eastern PA into southern New England during the day, with southwesterly 850 mb winds increasing to around 30 kt. Various models differ regarding strength of shear, but conditions will at least be marginally favorable for a few supercells and/or bowing segments developing within the surface trough, which will precede the primary cold front. Depending on the dominant storm mode, wind, hail, or a brief tornado will be possible, and parts of the area may be upgraded to a Slight Risk in later outlooks when predictability increases. ...Central High Plains to Missouri... Scattered storms are likely to be ongoing across parts of the central Plains, along and north of the east-west front. Predictability is low regarding where these storm clusters may be, but a general east/southeastward development is anticipated from KS/NE into MO and IL ahead of the front. Shear will be weak, but ample moisture and instability may lead to localized wind damage. To the west, low-level moisture will shift into eastern CO and WY, beneath steep lapse rates aloft. This will favor a few daytime cells capable of hail, with merging outflows likely as well producing strong wind gusts. ..Jewell.. 08/19/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Mon Aug 19 2019 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST...AND ACROSS THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... At least isolated severe storms are possible over parts of the Northeast, and from the central High Plains to the lower Missouri Valley. ...Synopsis... An upper low will move from James Bay into Quebec, with a leading shortwave trough developing east across the Great Lakes. Winds aloft will increase through the period over the northeastern states, with around 35 kt at 500 mb by late afternoon. Southerly surface winds will bring mid to upper 60s F dewpoints northward into southern New England as low pressure deepens over southern Quebec which will result in sufficient instability for strong to severe storms. To the west, an upper ridge will weaken as it moves from the Rockies into the Plains, with an upper trough moving across the Pacific Northwest. High pressure will exist over the northern Plains but surface winds will back over the northern High Plains resulting in westward moisture advection. To the southeast, the front will continue to progress southward across IA, IL and northern MO, with strong instability developing once again ahead of it. ...Northeast... Southwesterly low-level winds will maintain moisture advection across the region, which will increase instability but also result in areas of early day precipitation, as a warm front lifts north over New England. Meanwhile, shear will become more favorable for severe storms throughout the period as the upper trough approaches from the west. Forecast soundings indicate perhaps 1500 J/kg MUCAPE developing from eastern PA into southern New England during the day, with southwesterly 850 mb winds increasing to around 30 kt. Various models differ regarding strength of shear, but conditions will at least be marginally favorable for a few supercells and/or bowing segments developing within the surface trough, which will precede the primary cold front. Depending on the dominant storm mode, wind, hail, or a brief tornado will be possible, and parts of the area may be upgraded to a Slight Risk in later outlooks when predictability increases. ...Central High Plains to Missouri... Scattered storms are likely to be ongoing across parts of the central Plains, along and north of the east-west front. Predictability is low regarding where these storm clusters may be, but a general east/southeastward development is anticipated from KS/NE into MO and IL ahead of the front. Shear will be weak, but ample moisture and instability may lead to localized wind damage. To the west, low-level moisture will shift into eastern CO and WY, beneath steep lapse rates aloft. This will favor a few daytime cells capable of hail, with merging outflows likely as well producing strong wind gusts. ..Jewell.. 08/19/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Mon Aug 19 2019 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST...AND ACROSS THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... At least isolated severe storms are possible over parts of the Northeast, and from the central High Plains to the lower Missouri Valley. ...Synopsis... An upper low will move from James Bay into Quebec, with a leading shortwave trough developing east across the Great Lakes. Winds aloft will increase through the period over the northeastern states, with around 35 kt at 500 mb by late afternoon. Southerly surface winds will bring mid to upper 60s F dewpoints northward into southern New England as low pressure deepens over southern Quebec which will result in sufficient instability for strong to severe storms. To the west, an upper ridge will weaken as it moves from the Rockies into the Plains, with an upper trough moving across the Pacific Northwest. High pressure will exist over the northern Plains but surface winds will back over the northern High Plains resulting in westward moisture advection. To the southeast, the front will continue to progress southward across IA, IL and northern MO, with strong instability developing once again ahead of it. ...Northeast... Southwesterly low-level winds will maintain moisture advection across the region, which will increase instability but also result in areas of early day precipitation, as a warm front lifts north over New England. Meanwhile, shear will become more favorable for severe storms throughout the period as the upper trough approaches from the west. Forecast soundings indicate perhaps 1500 J/kg MUCAPE developing from eastern PA into southern New England during the day, with southwesterly 850 mb winds increasing to around 30 kt. Various models differ regarding strength of shear, but conditions will at least be marginally favorable for a few supercells and/or bowing segments developing within the surface trough, which will precede the primary cold front. Depending on the dominant storm mode, wind, hail, or a brief tornado will be possible, and parts of the area may be upgraded to a Slight Risk in later outlooks when predictability increases. ...Central High Plains to Missouri... Scattered storms are likely to be ongoing across parts of the central Plains, along and north of the east-west front. Predictability is low regarding where these storm clusters may be, but a general east/southeastward development is anticipated from KS/NE into MO and IL ahead of the front. Shear will be weak, but ample moisture and instability may lead to localized wind damage. To the west, low-level moisture will shift into eastern CO and WY, beneath steep lapse rates aloft. This will favor a few daytime cells capable of hail, with merging outflows likely as well producing strong wind gusts. ..Jewell.. 08/19/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0139 AM CDT Mon Aug 19 2019 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge over the western CONUS will continue to amplify into western Canada tomorrow with an upper-level shortwave trough approaching the Pacific Northwest. Subtropical moisture will begin to move into the Southwest as the ridge builds and into southern Montana/northern Wyoming with easterly low-level flow extending westward from the northern Plains. Isolated dry thunderstorms may develop across southern Montana and northern Wyoming. However, fuel conditions and uncertainty regarding thunderstorm coverage preclude introducing an isolated dry thunderstorm area at this time. ..Nauslar.. 08/19/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0139 AM CDT Mon Aug 19 2019 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge over the western CONUS will continue to amplify into western Canada tomorrow with an upper-level shortwave trough approaching the Pacific Northwest. Subtropical moisture will begin to move into the Southwest as the ridge builds and into southern Montana/northern Wyoming with easterly low-level flow extending westward from the northern Plains. Isolated dry thunderstorms may develop across southern Montana and northern Wyoming. However, fuel conditions and uncertainty regarding thunderstorm coverage preclude introducing an isolated dry thunderstorm area at this time. ..Nauslar.. 08/19/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0139 AM CDT Mon Aug 19 2019 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge over the western CONUS will continue to amplify into western Canada tomorrow with an upper-level shortwave trough approaching the Pacific Northwest. Subtropical moisture will begin to move into the Southwest as the ridge builds and into southern Montana/northern Wyoming with easterly low-level flow extending westward from the northern Plains. Isolated dry thunderstorms may develop across southern Montana and northern Wyoming. However, fuel conditions and uncertainty regarding thunderstorm coverage preclude introducing an isolated dry thunderstorm area at this time. ..Nauslar.. 08/19/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0139 AM CDT Mon Aug 19 2019 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge over the western CONUS will continue to amplify into western Canada tomorrow with an upper-level shortwave trough approaching the Pacific Northwest. Subtropical moisture will begin to move into the Southwest as the ridge builds and into southern Montana/northern Wyoming with easterly low-level flow extending westward from the northern Plains. Isolated dry thunderstorms may develop across southern Montana and northern Wyoming. However, fuel conditions and uncertainty regarding thunderstorm coverage preclude introducing an isolated dry thunderstorm area at this time. ..Nauslar.. 08/19/2019 ...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 0131 AM CDT Mon Aug 19 2019 Valid 191200Z - 201200Z ...Synopsis... Upper-level ridging will continue to strengthen and amplify over the western CONUS today. Much of the Intermountain West will remain hot/dry, and large-scale flow will be relatively weak across the much of the region. However, some residual stronger mid-level flow will remain over the northern Rockies/vicinity, and a weak mid-level shortwave trough is forecast to move over the northern Rockies as well. An elevated area was added across portions of southern and central Wyoming. West-southwest sustained surface winds of 12-20 mph with gusts of 25-30 mph and RH values of 8-15% are expected this afternoon and into the evening across the area. Additionally, very deep (10,000+ ft), dry, and unstable boundary layers will develop. This will be the fifth consecutive day of dry/breezy conditions with ERCs rising across portions of southern/western/central Wyoming (70-90th percentiles). ..Nauslar.. 08/19/2019 ...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 0131 AM CDT Mon Aug 19 2019 Valid 191200Z - 201200Z ...Synopsis... Upper-level ridging will continue to strengthen and amplify over the western CONUS today. Much of the Intermountain West will remain hot/dry, and large-scale flow will be relatively weak across the much of the region. However, some residual stronger mid-level flow will remain over the northern Rockies/vicinity, and a weak mid-level shortwave trough is forecast to move over the northern Rockies as well. An elevated area was added across portions of southern and central Wyoming. West-southwest sustained surface winds of 12-20 mph with gusts of 25-30 mph and RH values of 8-15% are expected this afternoon and into the evening across the area. Additionally, very deep (10,000+ ft), dry, and unstable boundary layers will develop. This will be the fifth consecutive day of dry/breezy conditions with ERCs rising across portions of southern/western/central Wyoming (70-90th percentiles). ..Nauslar.. 08/19/2019 ...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 0131 AM CDT Mon Aug 19 2019 Valid 191200Z - 201200Z ...Synopsis... Upper-level ridging will continue to strengthen and amplify over the western CONUS today. Much of the Intermountain West will remain hot/dry, and large-scale flow will be relatively weak across the much of the region. However, some residual stronger mid-level flow will remain over the northern Rockies/vicinity, and a weak mid-level shortwave trough is forecast to move over the northern Rockies as well. An elevated area was added across portions of southern and central Wyoming. West-southwest sustained surface winds of 12-20 mph with gusts of 25-30 mph and RH values of 8-15% are expected this afternoon and into the evening across the area. Additionally, very deep (10,000+ ft), dry, and unstable boundary layers will develop. This will be the fifth consecutive day of dry/breezy conditions with ERCs rising across portions of southern/western/central Wyoming (70-90th percentiles). ..Nauslar.. 08/19/2019 ...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 0131 AM CDT Mon Aug 19 2019 Valid 191200Z - 201200Z ...Synopsis... Upper-level ridging will continue to strengthen and amplify over the western CONUS today. Much of the Intermountain West will remain hot/dry, and large-scale flow will be relatively weak across the much of the region. However, some residual stronger mid-level flow will remain over the northern Rockies/vicinity, and a weak mid-level shortwave trough is forecast to move over the northern Rockies as well. An elevated area was added across portions of southern and central Wyoming. West-southwest sustained surface winds of 12-20 mph with gusts of 25-30 mph and RH values of 8-15% are expected this afternoon and into the evening across the area. Additionally, very deep (10,000+ ft), dry, and unstable boundary layers will develop. This will be the fifth consecutive day of dry/breezy conditions with ERCs rising across portions of southern/western/central Wyoming (70-90th percentiles). ..Nauslar.. 08/19/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0125 AM CDT Mon Aug 19 2019 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM ILLINOIS AND FAR WESTERN INDIANA WESTWARD INTO NEBRASKA... CORRECTED FOR GEOGRAPHIC SPELLING ERROR IN HEADLINE ...SUMMARY... Severe storms with damaging winds are possible over Illinois and parts of surrounding states on Tuesday. Severe storms with hail and wind are also expected over much of Nebraska. ...Synopsis... A shortwave trough will move southeastward across MB and ON, with 35-45 kt midlevel winds across the Upper MS Valley and Great Lakes. Heights will gradually lower from the mid MO Valley across the OH Valley and toward the Mid Atlantic by Wed morning. Cool temperatures aloft with -10 C at 500 mb will spread southeastward across MO and IL atop a moist and unstable air mass. Strong instability will also extend westward over much of the central Plains, with an east-west front along the KS/NE border and low pressure developing along the CO/KS border. This boundary will provide a focus for storms during the evening as the low-level jet develops and aids lift. ...IA/MO/IL/IN... Models indicate that an MCS will develop early in the morning over IA in a zone of warm advection with 40 kt west/southwest 850 mb winds, and will continue southeastward over IL and MO during the day. While much of this event may occur prior to peak heating, a very moist air mass and a few hours of heating will lead to 3000-4000 J/kg MUCAPE. Winds aloft will not be particularly strong this far south of the upper trough, but sufficient to aid forward propagation of an MCS. Damaging winds will be the primary concern. Western portions of this MCS will likely affect eastern MO, and may persist as far south as northeast AR. A higher probability threat corridor may need to be added in later outlooks once the MCS timing and position are better known. ...Eastern WY and northeast CO into NE... Strong heating will occur over WY, CO, and much of KS, but will be tempered along and north of the front into NE. Increasing easterly surface winds in the vicinity of the front will maintain 60s to 70s F dewpoints over NE, with near 60 F into northeast CO. Storms are expected to initiate within the well heated air mass of eastern CO and WY during the late afternoon, with increasing coverage north of the front in NE overnight. Damaging winds and hail will be the primary concerns. Deep-layer shear over NE may be sufficient for elevated supercells capable of very large hail given the large instability. An MCS could also develop into Wednesday morning over eastern NE into northwest MO. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% SIG - Slight Hail: 15% SIG - Slight ..Jewell.. 08/19/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0125 AM CDT Mon Aug 19 2019 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM ILLINOIS AND FAR WESTERN INDIANA WESTWARD INTO NEBRASKA... CORRECTED FOR GEOGRAPHIC SPELLING ERROR IN HEADLINE ...SUMMARY... Severe storms with damaging winds are possible over Illinois and parts of surrounding states on Tuesday. Severe storms with hail and wind are also expected over much of Nebraska. ...Synopsis... A shortwave trough will move southeastward across MB and ON, with 35-45 kt midlevel winds across the Upper MS Valley and Great Lakes. Heights will gradually lower from the mid MO Valley across the OH Valley and toward the Mid Atlantic by Wed morning. Cool temperatures aloft with -10 C at 500 mb will spread southeastward across MO and IL atop a moist and unstable air mass. Strong instability will also extend westward over much of the central Plains, with an east-west front along the KS/NE border and low pressure developing along the CO/KS border. This boundary will provide a focus for storms during the evening as the low-level jet develops and aids lift. ...IA/MO/IL/IN... Models indicate that an MCS will develop early in the morning over IA in a zone of warm advection with 40 kt west/southwest 850 mb winds, and will continue southeastward over IL and MO during the day. While much of this event may occur prior to peak heating, a very moist air mass and a few hours of heating will lead to 3000-4000 J/kg MUCAPE. Winds aloft will not be particularly strong this far south of the upper trough, but sufficient to aid forward propagation of an MCS. Damaging winds will be the primary concern. Western portions of this MCS will likely affect eastern MO, and may persist as far south as northeast AR. A higher probability threat corridor may need to be added in later outlooks once the MCS timing and position are better known. ...Eastern WY and northeast CO into NE... Strong heating will occur over WY, CO, and much of KS, but will be tempered along and north of the front into NE. Increasing easterly surface winds in the vicinity of the front will maintain 60s to 70s F dewpoints over NE, with near 60 F into northeast CO. Storms are expected to initiate within the well heated air mass of eastern CO and WY during the late afternoon, with increasing coverage north of the front in NE overnight. Damaging winds and hail will be the primary concerns. Deep-layer shear over NE may be sufficient for elevated supercells capable of very large hail given the large instability. An MCS could also develop into Wednesday morning over eastern NE into northwest MO. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% SIG - Slight Hail: 15% SIG - Slight ..Jewell.. 08/19/2019 Read more