Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Wed Aug 28 2019 Valid 291200Z - 301200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL PLAINS INTO PORTIONS OF THE UPPER GREAT LAKES... ...SUMMARY... A few strong to severe storms capable mainly of damaging winds are possible across portions of the upper Great Lakes to the middle Mississippi Valley Thursday afternoon and evening. Additional isolated severe storms capable of strong winds and hail are possible across parts of southern Nebraska into northern Kansas Thursday evening into the overnight hours. ...Synopsis... A shortwave trough will pivot eastward across the Great Lakes on Thursday, reinforcing larger-scale mean trough across much of eastern Canada into the north-central and northeastern U.S. Across the west, an upper ridge will persist, though a shortwave impulse will migrate across the northern Rockies along with various other subtle impulses tracking southeastward across the central Plains in deep layer northwesterly flow. At the surface, rich Gulf moisture will stream northward across the southern Plains into the central Plains on southerly low level flow. Some of this moisture will also make its way northeast across parts of IA/MO/IL and the Lake Michigan vicinity. A cold front draped across central MN into eastern/southern SD will progress east/southeast, extending from near Lakes Erie/Ontario southwestward toward central IL/MO and westward into central KS by Friday morning. This front will be a focus for thunderstorm development Thursday afternoon across the upper Great Lakes into the middle MS Valley vicinity and Thursday evening into the overnight hours across parts of KS/NE. ...Lake Michigan to Middle MS Valley Vicinity... Moisture return ahead of the cold front will be key for severe potential on Thursday afternoon and evening. Most guidance develops surface dewpoints in the mid and upper 60s as far northeast as northern IL into southern WI, though this corridor could be rather narrow. Further to the southwest into parts of southern IA/northern MO confidence is higher than better quality moisture will be in place. However, upper forcing for ascent decreases with southward extent further removed from the main upper shortwave impulse. Hi-res guidance as well as the NAM/GFS/ECMWF all develop storms along the front with various depictions of coverage and intensity. Nevertheless, at least a narrow corridor of weak to moderate instability should exist ahead of the front in the presence of 35-50 kt 0-6 km shear. Midlevel lapse rates are forecast to remain modest, around 6.5-7 C/km. Forecast soundings vary in how much low level SRH will be present, but this environment certainly could support a couple of supercells initially. As a result a few strong to severe storms appear likely, with damaging wind and possibly a couple of tornadoes. Some marginal hail also is possible with strongest storms. Questions about the northward extent of quality low level moisture and degree of destabilization ahead of the front remain. This is leading to uncertainty in the coverage/intensity/longevity of potential severe storms. As such, will include Marginal probabilities at this time, though upgrades may be needed in subsequent outlooks as evolution of moisture return hopefully becomes more clear. ...Central Plains... The western portion of the cold front will extend across southern NE at 00z. South/southeasterly low level flow will bring rich Gulf moisture northward across the Plains, with at least upper 60s surface dewpoints likely. Upslope flow and strong heating will likely initiate a few storms in the vicinity of the CO/NE/KS tri-state area near a triple point during the late afternoon/early evening. Very steep lapse rates and supercell wind profiles will support high-based storms capable of large hail and strong winds. Additional isolated storms may also try to develop southward near the CO/KS border along a dryline, but this activity likely will not become sustained for long due to a pretty deeply-mixed boundary layer and lack of stronger forcing. Further east across southern NE and KS, capping should suppress convection most of the day. More widespread convection is expected during the evening and overnight hours as a modest low level jet increases and warm advection atop the surface boundary coincides with a weak shortwave impulse migrating through northwesterly flow aloft. This activity could initially pose a hail or damaging wind threat early in its evolution, but storms are expected to quickly become elevated and likely the threat will transition toward more of a heavy rain concern (see WPC Excessive Rainfall Outlook) during the late evening and overnight hours. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Leitman.. 08/28/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1236 AM CDT Wed Aug 28 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely today, but an isolated strong storm cannot be ruled out over coastal parts of southern New England and also across the higher terrain of New Mexico and West Texas. ...Synopsis... A seasonably strong upper trough is forecast to move from the Great Lakes into New England by Thursday morning, as an upstream trough begins to amplify over the upper Midwest. A deep cyclone will drift northward toward Hudson Bay, as a smaller-scale surface wave and attendant cold front move across the northern Plains. NHC is forecasting Tropical Storm Erin to move northward and then turn northeastward well off of the New England coast by Thursday morning. ...Southern New England... As the upper trough and attendant cold front move eastward into the Northeast later today, a tropical moisture plume extending north of T.S. Erin will spread northward into southern New England. Buoyancy inland should remain very limited given poor midlevel lapse rates and widespread precipitation, but a modest increase in low-level shear/helicity may support a few weakly rotating cells this afternoon into the early evening across near-coastal areas of southern New England. At this time, the potential for appreciable surface-based destabilization appears too limited for the introduction of any severe probabilities. ...New Mexico/West TX... Strong thunderstorms are possible across the higher terrain of NM and west TX this afternoon into the early evening. Midlevel flow will remain weak across the region, but light southeasterly surface flow veering to northwesterly aloft will support effective shear of 20-25 kt, sufficient to support a few weakly organized cells given the presence of moderate to locally strong instability. The severe threat appears too limited in coverage and magnitude for the introduction of any probabilities at this point. ..Dean/Wendt.. 08/28/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1236 AM CDT Wed Aug 28 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely today, but an isolated strong storm cannot be ruled out over coastal parts of southern New England and also across the higher terrain of New Mexico and West Texas. ...Synopsis... A seasonably strong upper trough is forecast to move from the Great Lakes into New England by Thursday morning, as an upstream trough begins to amplify over the upper Midwest. A deep cyclone will drift northward toward Hudson Bay, as a smaller-scale surface wave and attendant cold front move across the northern Plains. NHC is forecasting Tropical Storm Erin to move northward and then turn northeastward well off of the New England coast by Thursday morning. ...Southern New England... As the upper trough and attendant cold front move eastward into the Northeast later today, a tropical moisture plume extending north of T.S. Erin will spread northward into southern New England. Buoyancy inland should remain very limited given poor midlevel lapse rates and widespread precipitation, but a modest increase in low-level shear/helicity may support a few weakly rotating cells this afternoon into the early evening across near-coastal areas of southern New England. At this time, the potential for appreciable surface-based destabilization appears too limited for the introduction of any severe probabilities. ...New Mexico/West TX... Strong thunderstorms are possible across the higher terrain of NM and west TX this afternoon into the early evening. Midlevel flow will remain weak across the region, but light southeasterly surface flow veering to northwesterly aloft will support effective shear of 20-25 kt, sufficient to support a few weakly organized cells given the presence of moderate to locally strong instability. The severe threat appears too limited in coverage and magnitude for the introduction of any probabilities at this point. ..Dean/Wendt.. 08/28/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1236 AM CDT Wed Aug 28 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely today, but an isolated strong storm cannot be ruled out over coastal parts of southern New England and also across the higher terrain of New Mexico and West Texas. ...Synopsis... A seasonably strong upper trough is forecast to move from the Great Lakes into New England by Thursday morning, as an upstream trough begins to amplify over the upper Midwest. A deep cyclone will drift northward toward Hudson Bay, as a smaller-scale surface wave and attendant cold front move across the northern Plains. NHC is forecasting Tropical Storm Erin to move northward and then turn northeastward well off of the New England coast by Thursday morning. ...Southern New England... As the upper trough and attendant cold front move eastward into the Northeast later today, a tropical moisture plume extending north of T.S. Erin will spread northward into southern New England. Buoyancy inland should remain very limited given poor midlevel lapse rates and widespread precipitation, but a modest increase in low-level shear/helicity may support a few weakly rotating cells this afternoon into the early evening across near-coastal areas of southern New England. At this time, the potential for appreciable surface-based destabilization appears too limited for the introduction of any severe probabilities. ...New Mexico/West TX... Strong thunderstorms are possible across the higher terrain of NM and west TX this afternoon into the early evening. Midlevel flow will remain weak across the region, but light southeasterly surface flow veering to northwesterly aloft will support effective shear of 20-25 kt, sufficient to support a few weakly organized cells given the presence of moderate to locally strong instability. The severe threat appears too limited in coverage and magnitude for the introduction of any probabilities at this point. ..Dean/Wendt.. 08/28/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Tue Aug 27 2019 Valid 280100Z - 281200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The severe thunderstorm threat is expected to generally remain low across the U.S. through the rest of tonight, though very isolated strong thunderstorms will be possible across portions of west Texas through mid-evening. ...West TX... A very isolated strong thunderstorm cluster southwest of Midland may persist for awhile this evening, driven by strong instability (MLCAPE greater than 3500 J/kg on 00Z MAF sounding) and marginally supportive deep-layer shear. Hail and/or locally severe wind gusts will be possible with this cluster as long as it remains intense, but the coverage and duration of the severe threat is expected to remain too limited to maintain severe probabilities in this area. See MCD 1882 for more information. ...AL... Thunderstorm clusters that earlier produced wind damage over portions of AL should continue to weaken with time this evening, with the onset boundary-layer stabilization. Any remaining wind risk is expected to largely diminish by 02Z. ..Dean.. 08/28/2019 Read more

No watches are valid as of Tue Aug 27 23:04:01 UTC 2019.

MD 1882 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF PERMIAN BASIN
Mesoscale Discussion 1882 NWS Storm Prediction Center Norman OK 0602 PM CDT Tue Aug 27 2019 Areas affected...Portions of Permian Basin Concerning...Severe potential...Watch unlikely Valid 272302Z - 280100Z Probability of Watch Issuance...5 percent SUMMARY...Isolated storms capable of strong/severe wind gusts as well as large hail may develop within the next hour or two. Storms are not expected to persist much beyond sunset. A WW is unlikely. DISCUSSION...Isolated convection may develop along a stalled cold front/residual outflow within the next hour or two. Strong heating within the Permian Basin has led to a cumulus field south of Midland becoming increasing agitated as temperatures are at or nearing convective temperature. With some mid-level flow enhanced by an MCV over the Hill Country and post-frontal southeasterly flow, low-level shear is quite strong (MAF/SJT VWP showing 0-3 km values of 35-40 kts). However, upper-level flow is quite weak under the influence of a broader anticyclone centered over the Desert Southwest. With steep low/mid-level lapse rates, a few storms may produce isolated large hail and strong/severe wind gusts. With weak anvil-winds, storm longevity is in question. Storms that can persist longer will likely diminish after sunset. A WW is not likely given the isolated/marginal nature of the threat. ..Wendt/Guyer.. 08/27/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SJT...MAF... LAT...LON 31400278 32040283 32150282 32930224 32940126 32690068 32520064 31780063 30940120 30910203 30960231 31400278 Read more

MD 1881 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF CENTRAL/NORTHEAST MISSISSIPPI THROUGH NORTHERN/CENTRAL ALABAMA
Mesoscale Discussion 1881 NWS Storm Prediction Center Norman OK 0356 PM CDT Tue Aug 27 2019 Areas affected...Parts of central/northeast Mississippi through northern/central Alabama Concerning...Severe potential...Watch unlikely Valid 272056Z - 272300Z Probability of Watch Issuance...5 percent SUMMARY...Strong storms may pose at least some risk for potentially damaging wind gusts late this afternoon. While it still appears unlikely that this will require a watch, trends will be monitored. DISCUSSION...Insolation within a very moist boundary layer (characterized by mid/upper 70s surface dew points) has contributed to a pre-cold frontal corridor of large CAPE (up to 3000 J/kg), along an axis across central Mississippi through northwest Alabama and southern Middle Tennessee. This has become the focus for increasing thunderstorm development, aided by forcing associated with a subtle mid-level trough within generally light westerly deep layer mean flow. Embedded within the weak troughing, a remnant mesoscale convective vortex is evident migrating across middle Tennessee, perhaps accompanied by a belt of at least modest (20-30 kt) flow in the 700-500 mb layer. This may be contributing to sufficient shear to support some organization of convection as it attempts to gradually grow upscale through the remainder of the afternoon. If this occurs, there may be a period of increasing potential for strong surface gusts approaching severe limits along expanding, strengthening surface cold pools. Otherwise, a few downbursts appear possible, accompanied by localized potentially damaging wind gusts. ..Kerr/Thompson.. 08/27/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OHX...BMX...HUN...MOB...MEG...JAN... LAT...LON 32829043 34008857 35038775 35218615 32778645 31808797 31709041 32829043 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z An elevated area was added for southern Wyoming and portions of northern Colorado where westerly 15-20 mph surface winds and RH values of 8-20% are likely tomorrow afternoon into the evening. Otherwise, only minor modifications were made to the isolated dry thunderstorm area. Nocturnal thunderstorms are possible across portions of Oregon tomorrow night. ..Nauslar.. 08/27/2019 .PREV DISCUSSION... /ISSUED 0208 AM CDT Tue Aug 27 2019/ ...Synopsis... The upper-level ridge across the western CONUS will slowly shift eastward during the D2/Wednesday period. A slight breakdown of the ridge is forecast to occur as a weak shortwave trough approaches the Pacific Northwest. Moisture influx into the Intermountain West from a remnant tropical system as well as the Monsoon will support thunderstorm development over a broad area. The main areas of concern will be across portions of northwest Arizona into the central Great Basin, northern California, and much of western/central Oregon. PWAT values around 0.8 inches and relatively slow storm motions will mean potential for some wetting rainfall. However, fuels have cured with recent hot/dry conditions which will support ignitions. Holdover potential will also exist with the expected return of hot/dry conditions. ...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 0254 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z An elevated area was added for southern Wyoming and portions of northern Colorado where westerly 15-20 mph surface winds and RH values of 8-20% are likely tomorrow afternoon into the evening. Otherwise, only minor modifications were made to the isolated dry thunderstorm area. Nocturnal thunderstorms are possible across portions of Oregon tomorrow night. ..Nauslar.. 08/27/2019 .PREV DISCUSSION... /ISSUED 0208 AM CDT Tue Aug 27 2019/ ...Synopsis... The upper-level ridge across the western CONUS will slowly shift eastward during the D2/Wednesday period. A slight breakdown of the ridge is forecast to occur as a weak shortwave trough approaches the Pacific Northwest. Moisture influx into the Intermountain West from a remnant tropical system as well as the Monsoon will support thunderstorm development over a broad area. The main areas of concern will be across portions of northwest Arizona into the central Great Basin, northern California, and much of western/central Oregon. PWAT values around 0.8 inches and relatively slow storm motions will mean potential for some wetting rainfall. However, fuels have cured with recent hot/dry conditions which will support ignitions. Holdover potential will also exist with the expected return of hot/dry conditions. ...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 0254 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z An elevated area was added for southern Wyoming and portions of northern Colorado where westerly 15-20 mph surface winds and RH values of 8-20% are likely tomorrow afternoon into the evening. Otherwise, only minor modifications were made to the isolated dry thunderstorm area. Nocturnal thunderstorms are possible across portions of Oregon tomorrow night. ..Nauslar.. 08/27/2019 .PREV DISCUSSION... /ISSUED 0208 AM CDT Tue Aug 27 2019/ ...Synopsis... The upper-level ridge across the western CONUS will slowly shift eastward during the D2/Wednesday period. A slight breakdown of the ridge is forecast to occur as a weak shortwave trough approaches the Pacific Northwest. Moisture influx into the Intermountain West from a remnant tropical system as well as the Monsoon will support thunderstorm development over a broad area. The main areas of concern will be across portions of northwest Arizona into the central Great Basin, northern California, and much of western/central Oregon. PWAT values around 0.8 inches and relatively slow storm motions will mean potential for some wetting rainfall. However, fuels have cured with recent hot/dry conditions which will support ignitions. Holdover potential will also exist with the expected return of hot/dry conditions. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Tue Aug 27 2019 Valid 272000Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF WEST TX AND ACROSS WI/UPPER MI... ...SUMMARY... Isolated severe thunderstorms are possible across parts of west Texas during the late afternoon and evening, and from east-central Minnesota to Upper Michigan this afternoon. No updates required. ..Jewell.. 08/27/2019 .PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Aug 27 2019/ ...WI/Upper MI this afternoon/evening... An embedded shortwave trough will move from MN across WI/Upper MI this afternoon/evening, around the southern periphery of a developing closed low over MB/western ON. Surface heating and residual boundary-layer dewpoints in the low-mid 50s, beneath 500 mb temperatures near -20 C, will result in low-midlevel lapse rates of 7-8 C/km and MLCAPE near 500 J/kg. Scattered low-topped thunderstorms are expected in the corridor immediately preceding the shortwave trough this afternoon/evening, and a few of the storms could produce strong outflow gusts and hail approaching one inch in diameter. ...Elsewhere... The richer low-level moisture has been shunted south of the stronger midlevel flow by a surface cold front and multiple convective outflows from overnight convection that have now spread southward to the I-20 corridor from north TX to central MS. Boundary-layer dewpoints of 76-80 F are present south of the outflow boundaries from southeast TX eastward, but vertical shear is weak and there is little focus for storm initiation aside from the outflows. Isolated strong gusts could occur with downbursts, but the overall severe threat is too limited to warrant introduction of any damaging wind probabilities. Farther west, very steep lapse rates were observed at MAF, though surface temperatures in excess of 105 F are needed to eliminate convective inhibition. There will be some threat for storms late this afternoon into early tonight along the surface front/stalling outflow, with isolated strong downbursts possible in the steep lapse rate environment. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Tue Aug 27 2019 Valid 272000Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF WEST TX AND ACROSS WI/UPPER MI... ...SUMMARY... Isolated severe thunderstorms are possible across parts of west Texas during the late afternoon and evening, and from east-central Minnesota to Upper Michigan this afternoon. No updates required. ..Jewell.. 08/27/2019 .PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Aug 27 2019/ ...WI/Upper MI this afternoon/evening... An embedded shortwave trough will move from MN across WI/Upper MI this afternoon/evening, around the southern periphery of a developing closed low over MB/western ON. Surface heating and residual boundary-layer dewpoints in the low-mid 50s, beneath 500 mb temperatures near -20 C, will result in low-midlevel lapse rates of 7-8 C/km and MLCAPE near 500 J/kg. Scattered low-topped thunderstorms are expected in the corridor immediately preceding the shortwave trough this afternoon/evening, and a few of the storms could produce strong outflow gusts and hail approaching one inch in diameter. ...Elsewhere... The richer low-level moisture has been shunted south of the stronger midlevel flow by a surface cold front and multiple convective outflows from overnight convection that have now spread southward to the I-20 corridor from north TX to central MS. Boundary-layer dewpoints of 76-80 F are present south of the outflow boundaries from southeast TX eastward, but vertical shear is weak and there is little focus for storm initiation aside from the outflows. Isolated strong gusts could occur with downbursts, but the overall severe threat is too limited to warrant introduction of any damaging wind probabilities. Farther west, very steep lapse rates were observed at MAF, though surface temperatures in excess of 105 F are needed to eliminate convective inhibition. There will be some threat for storms late this afternoon into early tonight along the surface front/stalling outflow, with isolated strong downbursts possible in the steep lapse rate environment. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Tue Aug 27 2019 Valid 272000Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF WEST TX AND ACROSS WI/UPPER MI... ...SUMMARY... Isolated severe thunderstorms are possible across parts of west Texas during the late afternoon and evening, and from east-central Minnesota to Upper Michigan this afternoon. No updates required. ..Jewell.. 08/27/2019 .PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Aug 27 2019/ ...WI/Upper MI this afternoon/evening... An embedded shortwave trough will move from MN across WI/Upper MI this afternoon/evening, around the southern periphery of a developing closed low over MB/western ON. Surface heating and residual boundary-layer dewpoints in the low-mid 50s, beneath 500 mb temperatures near -20 C, will result in low-midlevel lapse rates of 7-8 C/km and MLCAPE near 500 J/kg. Scattered low-topped thunderstorms are expected in the corridor immediately preceding the shortwave trough this afternoon/evening, and a few of the storms could produce strong outflow gusts and hail approaching one inch in diameter. ...Elsewhere... The richer low-level moisture has been shunted south of the stronger midlevel flow by a surface cold front and multiple convective outflows from overnight convection that have now spread southward to the I-20 corridor from north TX to central MS. Boundary-layer dewpoints of 76-80 F are present south of the outflow boundaries from southeast TX eastward, but vertical shear is weak and there is little focus for storm initiation aside from the outflows. Isolated strong gusts could occur with downbursts, but the overall severe threat is too limited to warrant introduction of any damaging wind probabilities. Farther west, very steep lapse rates were observed at MAF, though surface temperatures in excess of 105 F are needed to eliminate convective inhibition. There will be some threat for storms late this afternoon into early tonight along the surface front/stalling outflow, with isolated strong downbursts possible in the steep lapse rate environment. Read more

No Mesoscale Discussions are in effect as of Tue Aug 27 19:31:01 UTC 2019.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely on Wednesday, but an isolated strong storm cannot be ruled out over parts of the Northeast and Texas. ...Synopsis... An upper low will remain over northern Ontario with a broad area of cyclonic flow aloft from the northern Plains eastward across the Great Lakes and New England. Within this flow regime, a leading shortwave trough will move from the OH Valley into the Northeast, with an associated wind shift/weak surface trough over eastern NY and PA by Wednesday afternoon. Ahead of the front, dewpoints in the 60s F will gradually spread north, resulting in marginal instability supporting scattered thunderstorms. To the west, high pressure will result in relatively stable conditions over much of the central and northern plains, MS and OH Valleys, with decreasing moisture to the northern Gulf Coast by Thursday morning. Very weak levels of instability may result in a few lightning strikes over far northern ND and MN overnight as low-amplitude but strong wave moves southeastward out of Canada providing lift and steepening lapse rates aloft, but severe weather is unlikely. Elsewhere, scattered storms are likely from northern into central TX as a east-west front slows. Sufficient instability will exist for strong updrafts, but weak shear and lack of large-scale support suggests any strong wind gusts should be disorganized and localized. ...Northeast... Scattered storms are likely along a cold front during the day over central PA and NY, and into southern New England associated with warm/moist advection. Despite the presence of the upper trough, lapse rates are forecast to be poor. In addition, mean wind speeds in the lowest few km do not appear to support severe wind gusts along the front. Low-level winds do veer with height over southern New England, where dewpoints will rise to 68-70 F. However, wind speeds and thus SRH will remain weak here as well, generally under 100 m2/s2. Depending on mesocale factors during the day, a Marginal could be needed for isolated weakly rotating storms. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5% - None Hail: <5% - None ..Jewell.. 08/27/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely on Wednesday, but an isolated strong storm cannot be ruled out over parts of the Northeast and Texas. ...Synopsis... An upper low will remain over northern Ontario with a broad area of cyclonic flow aloft from the northern Plains eastward across the Great Lakes and New England. Within this flow regime, a leading shortwave trough will move from the OH Valley into the Northeast, with an associated wind shift/weak surface trough over eastern NY and PA by Wednesday afternoon. Ahead of the front, dewpoints in the 60s F will gradually spread north, resulting in marginal instability supporting scattered thunderstorms. To the west, high pressure will result in relatively stable conditions over much of the central and northern plains, MS and OH Valleys, with decreasing moisture to the northern Gulf Coast by Thursday morning. Very weak levels of instability may result in a few lightning strikes over far northern ND and MN overnight as low-amplitude but strong wave moves southeastward out of Canada providing lift and steepening lapse rates aloft, but severe weather is unlikely. Elsewhere, scattered storms are likely from northern into central TX as a east-west front slows. Sufficient instability will exist for strong updrafts, but weak shear and lack of large-scale support suggests any strong wind gusts should be disorganized and localized. ...Northeast... Scattered storms are likely along a cold front during the day over central PA and NY, and into southern New England associated with warm/moist advection. Despite the presence of the upper trough, lapse rates are forecast to be poor. In addition, mean wind speeds in the lowest few km do not appear to support severe wind gusts along the front. Low-level winds do veer with height over southern New England, where dewpoints will rise to 68-70 F. However, wind speeds and thus SRH will remain weak here as well, generally under 100 m2/s2. Depending on mesocale factors during the day, a Marginal could be needed for isolated weakly rotating storms. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5% - None Hail: <5% - None ..Jewell.. 08/27/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely on Wednesday, but an isolated strong storm cannot be ruled out over parts of the Northeast and Texas. ...Synopsis... An upper low will remain over northern Ontario with a broad area of cyclonic flow aloft from the northern Plains eastward across the Great Lakes and New England. Within this flow regime, a leading shortwave trough will move from the OH Valley into the Northeast, with an associated wind shift/weak surface trough over eastern NY and PA by Wednesday afternoon. Ahead of the front, dewpoints in the 60s F will gradually spread north, resulting in marginal instability supporting scattered thunderstorms. To the west, high pressure will result in relatively stable conditions over much of the central and northern plains, MS and OH Valleys, with decreasing moisture to the northern Gulf Coast by Thursday morning. Very weak levels of instability may result in a few lightning strikes over far northern ND and MN overnight as low-amplitude but strong wave moves southeastward out of Canada providing lift and steepening lapse rates aloft, but severe weather is unlikely. Elsewhere, scattered storms are likely from northern into central TX as a east-west front slows. Sufficient instability will exist for strong updrafts, but weak shear and lack of large-scale support suggests any strong wind gusts should be disorganized and localized. ...Northeast... Scattered storms are likely along a cold front during the day over central PA and NY, and into southern New England associated with warm/moist advection. Despite the presence of the upper trough, lapse rates are forecast to be poor. In addition, mean wind speeds in the lowest few km do not appear to support severe wind gusts along the front. Low-level winds do veer with height over southern New England, where dewpoints will rise to 68-70 F. However, wind speeds and thus SRH will remain weak here as well, generally under 100 m2/s2. Depending on mesocale factors during the day, a Marginal could be needed for isolated weakly rotating storms. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5% - None Hail: <5% - None ..Jewell.. 08/27/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 27 2019 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely on Wednesday, but an isolated strong storm cannot be ruled out over parts of the Northeast and Texas. ...Synopsis... An upper low will remain over northern Ontario with a broad area of cyclonic flow aloft from the northern Plains eastward across the Great Lakes and New England. Within this flow regime, a leading shortwave trough will move from the OH Valley into the Northeast, with an associated wind shift/weak surface trough over eastern NY and PA by Wednesday afternoon. Ahead of the front, dewpoints in the 60s F will gradually spread north, resulting in marginal instability supporting scattered thunderstorms. To the west, high pressure will result in relatively stable conditions over much of the central and northern plains, MS and OH Valleys, with decreasing moisture to the northern Gulf Coast by Thursday morning. Very weak levels of instability may result in a few lightning strikes over far northern ND and MN overnight as low-amplitude but strong wave moves southeastward out of Canada providing lift and steepening lapse rates aloft, but severe weather is unlikely. Elsewhere, scattered storms are likely from northern into central TX as a east-west front slows. Sufficient instability will exist for strong updrafts, but weak shear and lack of large-scale support suggests any strong wind gusts should be disorganized and localized. ...Northeast... Scattered storms are likely along a cold front during the day over central PA and NY, and into southern New England associated with warm/moist advection. Despite the presence of the upper trough, lapse rates are forecast to be poor. In addition, mean wind speeds in the lowest few km do not appear to support severe wind gusts along the front. Low-level winds do veer with height over southern New England, where dewpoints will rise to 68-70 F. However, wind speeds and thus SRH will remain weak here as well, generally under 100 m2/s2. Depending on mesocale factors during the day, a Marginal could be needed for isolated weakly rotating storms. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5% - None Hail: <5% - None ..Jewell.. 08/27/2019 Read more

MD 1880 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EAST-CENTRAL MINNESOTA...NORTHERN WISCONSIN...AND PORTIONS OF THE UPPER PENINSULA OF MICHIGAN
Mesoscale Discussion 1880 NWS Storm Prediction Center Norman OK 1231 PM CDT Tue Aug 27 2019 Areas affected...east-central Minnesota...northern Wisconsin...and portions of the Upper Peninsula of Michigan Concerning...Severe potential...Watch unlikely Valid 271731Z - 271930Z Probability of Watch Issuance...5 percent SUMMARY...Areas of gusty winds and small hail are likely with storms moving through the discussion area this afternoon. A WW issuance is not anticipated for this activity. DISCUSSION...A small linear band of convection has evolved from near D25 to TKV across north-central Wisconsin. Additional convection was deepening across central Minnesota near STC. These storms are in an environment characterized by appreciable mid-level flow (35-45 kts), unidirectional wind profiles, and steep lapse rates associated with a broad mid-level trough centered over western Ontario. These lapse rates and near 60F dewpoints were boosting MUCAPE values to the 1000-1500 J/kg range while also supporting surface-based convection. Downdraft potential within ongoing convection should foster an isolated damaging-wind threat, and small hail will also be possible. Over time, models/PFCs suggest that cooling mid-level temperatures will continue to maintain instability and contribute to deepening convection over time. Lift associated with approaching upstream shortwaves and continued insolation will also further support an increase in scattered, marginally severe convection through the day. This diurnally driven severe threat should be too isolated/marginal for a WW issuance, however. ..Cook/Thompson.. 08/27/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB...DLH...ARX...MPX... LAT...LON 46429285 46239374 45989480 45469488 45059408 44839283 44749130 44818981 45048848 45368759 45718701 46108669 46518665 46768689 46968758 47138819 47138912 46999006 46919096 46829126 46429285 Read more