Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0130 PM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... No changes. Previous discussion follows. ..Bentley.. 08/20/2019 .PREV DISCUSSION... /ISSUED 0142 AM CDT Tue Aug 20 2019/ ...Synopsis... An upper-level shortwave trough is forecast to move into the Pacific Northwest and northern Rockies tomorrow. The trough will likely deepen and stretch through northern California and much of the Great Basin. An associated surface cold front will move eastward across the Pacific Northwest and into northern California, the northern Great Basin, and the northern Rockies. Dry/breezy conditions will likely develop across portions of the Columbia Basin/Gorge and into central/eastern Oregon ahead of the approaching cold front. Elevated/locally critical conditions may develop, but the window for these conditions should be relatively short-lived and followed by cool/moist conditions. Thunderstorms may also develop along/ahead of this cold front across eastern Washington into the Idaho Panhandle and western Montana. However, given the higher precipitable water values (0.8-1.2") along/just ahead of the cold front and the cool/moist airmass behind the front, an isolated dry thunderstorm area was not included. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1811 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHERN VA...MD...SOUTH-CENTRAL PA
Mesoscale Discussion 1811 NWS Storm Prediction Center Norman OK 0119 PM CDT Tue Aug 20 2019 Areas affected...northern VA...MD...south-central PA Concerning...Severe potential...Watch possible Valid 201819Z - 201915Z Probability of Watch Issuance...40 percent SUMMARY...Scattered storm development is expected this afternoon. Isolated strong gusts (40-55mph) capable of pockets of wind damage are forecast through late afternoon. DISCUSSION...Visible satellite imagery shows a cluster of thunderstorms developing over the eastern part of the central Appalachians aided in part by a weak MCV and strong surface heating. Surface analysis indicates temperatures have warmed into the lower-middle 90s degrees F with dewpoints ranging from the upper 60s-lower 70s. RAP forecast soundings appear valid (based on surface conditions) and around 2500 J/kg MLCAPE is noted near the greater D.C. vicinity. Although flow is generally weak through the troposphere, steepened 0-2km lapse rates and PW around 1.7 inches suggest the stronger multicells that develop will be capable of an isolated risk for damaging gusts. It is not clear that the magnitude/coverage of the strong/locally severe storm risk warrants a severe thunderstorm watch, nonetheless, convective trends will be monitored. ..Smith/Thompson.. 08/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...CTP...LWX...PBZ...RLX... LAT...LON 38897934 38957937 40047833 40127769 39937667 39467636 38277723 38037817 38337923 38897934 Read more

WW 0603 Status Updates
STATUS FOR WATCH 0603 HAS NOT BEEN ISSUED YET Read more

WW 0602 Status Updates
STATUS REPORT ON WW 602 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNE COU TO 40 NW ALN TO 15 SW BLV TO 35 E SLO. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1810 ..SMITH..08/20/19 ATTN...WFO...DVN...LSX...ILX...LOT...EAX... STATUS REPORT FOR WS 602 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC013-025-033-061-083-101-121-133-159-189-201840- IL . ILLINOIS COUNTIES INCLUDED ARE CALHOUN CLAY CRAWFORD GREENE JERSEY LAWRENCE MARION MONROE RICHLAND WASHINGTON MOC071-099-113-139-163-183-189-219-510-201840- MO . MISSOURI COUNTIES INCLUDED ARE FRANKLIN JEFFERSON LINCOLN MONTGOMERY PIKE ST. CHARLES ST. LOUIS WARREN MISSOURI INDEPENDENT CITIES INCLUDED ARE Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY ACROSS PARTS OF THE NORTHERN MID ATLANTIC STATES AND NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible across parts of the northern Mid Atlantic Coast states into New England Wednesday. Additional strong to severe storms are possible in a corridor from the central Plains into the lower Ohio Valley, and near the Rockies. ...Synopsis... The stronger westerlies appear to be undergoing amplification, but may remain largely confined to Canada and the northern tier of the U.S. through this period. Within this regime, larger-scale mid/upper troughing is forecast to progress inland of the British Columbia and Pacific Northwest coast, through the Canadian Rockies and northern U.S. intermountain region by late Wednesday night. As this occurs, sharp downstream ridging should shift eastward across interior Canada, while large-scale troughing to the east develops across Ontario/Quebec and the Great Lakes region, toward the northern Atlantic coast. Models indicate the eastern troughing will include an embedded mid-level low, with at least a couple of significant perturbations migrating through the broader cyclonic flow. One of these is forecast to be in the process of digging into the upper Great Lakes region early Wednesday, before accelerating eastward and northeastward into and through Quebec by 12Z Thursday. It appears that associated forcing for ascent will support significant surface cyclogenesis across Quebec, with the most rapid deepening to the northwest of the St. Lawrence Valley Wednesday night. A front trailing from the developing cyclone is expected to advance through much of the Upper Midwest, mid Missouri Valley and northern Plains by early Wednesday, before continuing southeastward into/through New England, the Ohio and middle Mississippi Valleys and the central Plains by 12Z Thursday. The front will be preceded by the remnants of convective outflow from the large ongoing convective system (now advancing into the lower Ohio Valley), which may still be evident across the central Appalachians and lower Ohio Valley early Wednesday. Seasonably moist air along and ahead of pre-frontal surface troughing across parts of the Northeast, and the convective outflow/cold front extending westward across the central Appalachians into the Rockies, appears likely to contribute to moderate to strong potential instability with daytime heating Wednesday. This is expected to provide support for areas of strong thunderstorm development, some of which will probably pose at least some risk for severe wind and hail. ....Northeast... The extent to which to which the stronger surface cyclogenesis impacts convective potential across the region during this period remains unclear, given the apparent overnight timing of the most rapid surface deepening. Additionally, it is possible that the associated surface cold front may become a focus for thunderstorm development, but this may be mostly over portions of southeastern Ontario and southwest Quebec prior to Wednesday evening. However, the primary convective potential seems likely in association with forcing for ascent accompanying a remnant convectively generated or enhanced perturbation, which is forecast to develop northeastward ahead of the primary troughing within the westerlies, from the lee of the lower Great Lakes region through New England by Wednesday evening. A belt of enhanced southwesterly lower/mid tropospheric flow (on the order of 30-40+ kt), coupled with at least modest destabilization (CAPE of 1000-2000+ J/kg) near/ahead of a developing pre-frontal surface trough, may provide an environment conducive to organized severe storm development across parts of eastern New York and Pennsylvania and much of New Jersey through much of New England. Potentially damaging wind gusts appear the primary hazard, but there may be at least some risk for a tornado or two, particularly across the Hudson/Champlain Valley vicinity into western New England Wednesday afternoon. ...Ohio and middle Mississippi Valleys into high Plains... It appears that the focusing boundaries for moderate to strong boundary layer destabilization and thunderstorm development will be south of the stronger shear associated with the westerlies. However, thermodynamic profiles characterized by relatively steep lapse rates may still be favorable for convection capable of producing hail and strong wind gusts associated with downbursts and convectively generated cold pools. Too much uncertainty still exists concerning sub-synoptic features to attempt to delineate areas of higher ("slight risk") severe probabilities at this time. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 5% - Marginal ..Kerr.. 08/20/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY ACROSS PARTS OF THE NORTHERN MID ATLANTIC STATES AND NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible across parts of the northern Mid Atlantic Coast states into New England Wednesday. Additional strong to severe storms are possible in a corridor from the central Plains into the lower Ohio Valley, and near the Rockies. ...Synopsis... The stronger westerlies appear to be undergoing amplification, but may remain largely confined to Canada and the northern tier of the U.S. through this period. Within this regime, larger-scale mid/upper troughing is forecast to progress inland of the British Columbia and Pacific Northwest coast, through the Canadian Rockies and northern U.S. intermountain region by late Wednesday night. As this occurs, sharp downstream ridging should shift eastward across interior Canada, while large-scale troughing to the east develops across Ontario/Quebec and the Great Lakes region, toward the northern Atlantic coast. Models indicate the eastern troughing will include an embedded mid-level low, with at least a couple of significant perturbations migrating through the broader cyclonic flow. One of these is forecast to be in the process of digging into the upper Great Lakes region early Wednesday, before accelerating eastward and northeastward into and through Quebec by 12Z Thursday. It appears that associated forcing for ascent will support significant surface cyclogenesis across Quebec, with the most rapid deepening to the northwest of the St. Lawrence Valley Wednesday night. A front trailing from the developing cyclone is expected to advance through much of the Upper Midwest, mid Missouri Valley and northern Plains by early Wednesday, before continuing southeastward into/through New England, the Ohio and middle Mississippi Valleys and the central Plains by 12Z Thursday. The front will be preceded by the remnants of convective outflow from the large ongoing convective system (now advancing into the lower Ohio Valley), which may still be evident across the central Appalachians and lower Ohio Valley early Wednesday. Seasonably moist air along and ahead of pre-frontal surface troughing across parts of the Northeast, and the convective outflow/cold front extending westward across the central Appalachians into the Rockies, appears likely to contribute to moderate to strong potential instability with daytime heating Wednesday. This is expected to provide support for areas of strong thunderstorm development, some of which will probably pose at least some risk for severe wind and hail. ....Northeast... The extent to which to which the stronger surface cyclogenesis impacts convective potential across the region during this period remains unclear, given the apparent overnight timing of the most rapid surface deepening. Additionally, it is possible that the associated surface cold front may become a focus for thunderstorm development, but this may be mostly over portions of southeastern Ontario and southwest Quebec prior to Wednesday evening. However, the primary convective potential seems likely in association with forcing for ascent accompanying a remnant convectively generated or enhanced perturbation, which is forecast to develop northeastward ahead of the primary troughing within the westerlies, from the lee of the lower Great Lakes region through New England by Wednesday evening. A belt of enhanced southwesterly lower/mid tropospheric flow (on the order of 30-40+ kt), coupled with at least modest destabilization (CAPE of 1000-2000+ J/kg) near/ahead of a developing pre-frontal surface trough, may provide an environment conducive to organized severe storm development across parts of eastern New York and Pennsylvania and much of New Jersey through much of New England. Potentially damaging wind gusts appear the primary hazard, but there may be at least some risk for a tornado or two, particularly across the Hudson/Champlain Valley vicinity into western New England Wednesday afternoon. ...Ohio and middle Mississippi Valleys into high Plains... It appears that the focusing boundaries for moderate to strong boundary layer destabilization and thunderstorm development will be south of the stronger shear associated with the westerlies. However, thermodynamic profiles characterized by relatively steep lapse rates may still be favorable for convection capable of producing hail and strong wind gusts associated with downbursts and convectively generated cold pools. Too much uncertainty still exists concerning sub-synoptic features to attempt to delineate areas of higher ("slight risk") severe probabilities at this time. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 5% - Marginal ..Kerr.. 08/20/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Aug 20 2019 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WEDNESDAY ACROSS PARTS OF THE NORTHERN MID ATLANTIC STATES AND NEW ENGLAND... ...SUMMARY... Severe thunderstorms are possible across parts of the northern Mid Atlantic Coast states into New England Wednesday. Additional strong to severe storms are possible in a corridor from the central Plains into the lower Ohio Valley, and near the Rockies. ...Synopsis... The stronger westerlies appear to be undergoing amplification, but may remain largely confined to Canada and the northern tier of the U.S. through this period. Within this regime, larger-scale mid/upper troughing is forecast to progress inland of the British Columbia and Pacific Northwest coast, through the Canadian Rockies and northern U.S. intermountain region by late Wednesday night. As this occurs, sharp downstream ridging should shift eastward across interior Canada, while large-scale troughing to the east develops across Ontario/Quebec and the Great Lakes region, toward the northern Atlantic coast. Models indicate the eastern troughing will include an embedded mid-level low, with at least a couple of significant perturbations migrating through the broader cyclonic flow. One of these is forecast to be in the process of digging into the upper Great Lakes region early Wednesday, before accelerating eastward and northeastward into and through Quebec by 12Z Thursday. It appears that associated forcing for ascent will support significant surface cyclogenesis across Quebec, with the most rapid deepening to the northwest of the St. Lawrence Valley Wednesday night. A front trailing from the developing cyclone is expected to advance through much of the Upper Midwest, mid Missouri Valley and northern Plains by early Wednesday, before continuing southeastward into/through New England, the Ohio and middle Mississippi Valleys and the central Plains by 12Z Thursday. The front will be preceded by the remnants of convective outflow from the large ongoing convective system (now advancing into the lower Ohio Valley), which may still be evident across the central Appalachians and lower Ohio Valley early Wednesday. Seasonably moist air along and ahead of pre-frontal surface troughing across parts of the Northeast, and the convective outflow/cold front extending westward across the central Appalachians into the Rockies, appears likely to contribute to moderate to strong potential instability with daytime heating Wednesday. This is expected to provide support for areas of strong thunderstorm development, some of which will probably pose at least some risk for severe wind and hail. ....Northeast... The extent to which to which the stronger surface cyclogenesis impacts convective potential across the region during this period remains unclear, given the apparent overnight timing of the most rapid surface deepening. Additionally, it is possible that the associated surface cold front may become a focus for thunderstorm development, but this may be mostly over portions of southeastern Ontario and southwest Quebec prior to Wednesday evening. However, the primary convective potential seems likely in association with forcing for ascent accompanying a remnant convectively generated or enhanced perturbation, which is forecast to develop northeastward ahead of the primary troughing within the westerlies, from the lee of the lower Great Lakes region through New England by Wednesday evening. A belt of enhanced southwesterly lower/mid tropospheric flow (on the order of 30-40+ kt), coupled with at least modest destabilization (CAPE of 1000-2000+ J/kg) near/ahead of a developing pre-frontal surface trough, may provide an environment conducive to organized severe storm development across parts of eastern New York and Pennsylvania and much of New Jersey through much of New England. Potentially damaging wind gusts appear the primary hazard, but there may be at least some risk for a tornado or two, particularly across the Hudson/Champlain Valley vicinity into western New England Wednesday afternoon. ...Ohio and middle Mississippi Valleys into high Plains... It appears that the focusing boundaries for moderate to strong boundary layer destabilization and thunderstorm development will be south of the stronger shear associated with the westerlies. However, thermodynamic profiles characterized by relatively steep lapse rates may still be favorable for convection capable of producing hail and strong wind gusts associated with downbursts and convectively generated cold pools. Too much uncertainty still exists concerning sub-synoptic features to attempt to delineate areas of higher ("slight risk") severe probabilities at this time. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 5% - Marginal ..Kerr.. 08/20/2019 Read more

MD 1810 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR MOST OF INDIANA AND PORTIONS OF SOUTHERN ILLINOIS
Mesoscale Discussion 1810 NWS Storm Prediction Center Norman OK 1212 PM CDT Tue Aug 20 2019 Areas affected...Most of Indiana and portions of southern Illinois Concerning...Severe potential...Watch possible Valid 201712Z - 201915Z Probability of Watch Issuance...40 percent SUMMARY...Locally damaging winds remain possible with the progression of an MCS southeast through the area. A Severe Thunderstorm Watch is possible. DISCUSSION...A well-organized MCS with attendant MCV continues moving southeast at 35-40 kt over Illinois with a slowly broadening lead convective line arcing from Chicago to near St. Louis. The main limiting factor for a more widespread severe wind threat is weak low-to-mid level wind shear present ahead of the MCS, which should support a continuation of a significantly upshear-tilted system and slowly weakening mesoscale rear inflow. However, ample instability owing to rich boundary-layer moisture and some daytime heating (prior to the anvil spreading over the area), and minimal convective inhibition, should support the continued generation of some convection along the outflow through the afternoon. In addition, widely-scattered storms should continue to develop ahead of the MCS, particularly in the vicinity of a mesoscale band of confluence stretching northwest to southeast across southern Indiana. Although the MCS should continue south and eastward in a somewhat disorganized state (compared to this morning), low-level lapse rates will be sufficient to support locally damaging winds with the stronger convective pulses. The main uncertainty is whether or not the coverage of the threat will be large enough to warrant a Severe Thunderstorm Watch. ..Coniglio/Thompson.. 08/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...IWX...IND...PAH...LOT...ILX...LSX... LAT...LON 41198745 41458736 41658678 41638621 41318549 40588525 39628538 38988573 38598633 38168717 37888793 37808833 37678913 37828952 38098990 38378995 38578990 38938887 39538786 40078755 40538748 41198745 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1155 AM CDT Tue Aug 20 2019 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... No changes. Previous discussion follows. ..Bentley.. 08/20/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Tue Aug 20 2019/ ...Synopsis... An upper-level ridge will continue to amplify over the western CONUS into western Canada today as an upper-level shortwave trough approaches the Pacific Northwest. Subtropical moisture will begin to move northward into the Southwest and eastward into southwest Montana from the northern Plains. A surface cold front will push southward up against the eastern slopes of the northern/central Rockies with hot/dry/unstable conditions prevailing across much of the Intermountain West. Isolated dry thunderstorms may form across southwest Montana and northwest Wyoming this afternoon/evening. However, given the uncertainty regarding coverage and marginal fuel conditions where storms are currently forecast to develop, an isolated dry thunderstorm area was not included. ...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 1155 AM CDT Tue Aug 20 2019 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... No changes. Previous discussion follows. ..Bentley.. 08/20/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Tue Aug 20 2019/ ...Synopsis... An upper-level ridge will continue to amplify over the western CONUS into western Canada today as an upper-level shortwave trough approaches the Pacific Northwest. Subtropical moisture will begin to move northward into the Southwest and eastward into southwest Montana from the northern Plains. A surface cold front will push southward up against the eastern slopes of the northern/central Rockies with hot/dry/unstable conditions prevailing across much of the Intermountain West. Isolated dry thunderstorms may form across southwest Montana and northwest Wyoming this afternoon/evening. However, given the uncertainty regarding coverage and marginal fuel conditions where storms are currently forecast to develop, an isolated dry thunderstorm area was not included. ...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 1155 AM CDT Tue Aug 20 2019 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... No changes. Previous discussion follows. ..Bentley.. 08/20/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Tue Aug 20 2019/ ...Synopsis... An upper-level ridge will continue to amplify over the western CONUS into western Canada today as an upper-level shortwave trough approaches the Pacific Northwest. Subtropical moisture will begin to move northward into the Southwest and eastward into southwest Montana from the northern Plains. A surface cold front will push southward up against the eastern slopes of the northern/central Rockies with hot/dry/unstable conditions prevailing across much of the Intermountain West. Isolated dry thunderstorms may form across southwest Montana and northwest Wyoming this afternoon/evening. However, given the uncertainty regarding coverage and marginal fuel conditions where storms are currently forecast to develop, an isolated dry thunderstorm area was not included. ...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 1155 AM CDT Tue Aug 20 2019 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... No changes. Previous discussion follows. ..Bentley.. 08/20/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Tue Aug 20 2019/ ...Synopsis... An upper-level ridge will continue to amplify over the western CONUS into western Canada today as an upper-level shortwave trough approaches the Pacific Northwest. Subtropical moisture will begin to move northward into the Southwest and eastward into southwest Montana from the northern Plains. A surface cold front will push southward up against the eastern slopes of the northern/central Rockies with hot/dry/unstable conditions prevailing across much of the Intermountain West. Isolated dry thunderstorms may form across southwest Montana and northwest Wyoming this afternoon/evening. However, given the uncertainty regarding coverage and marginal fuel conditions where storms are currently forecast to develop, an isolated dry thunderstorm area was not included. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0602 Status Updates
STATUS REPORT ON WW 602 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 ENE CDJ TO 10 SSW UIN TO 15 ENE ALN TO 10 ESE CMI TO 35 ENE MMO. ..SMITH..08/20/19 ATTN...WFO...DVN...LSX...ILX...LOT...EAX... STATUS REPORT FOR WS 602 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC005-013-019-023-025-027-029-033-035-041-045-049-051-061-075- 079-083-091-101-117-119-121-133-135-139-149-159-163-173-183-189- 197-201720- IL . ILLINOIS COUNTIES INCLUDED ARE BOND CALHOUN CHAMPAIGN CLARK CLAY CLINTON COLES CRAWFORD CUMBERLAND DOUGLAS EDGAR EFFINGHAM FAYETTE GREENE IROQUOIS JASPER JERSEY KANKAKEE LAWRENCE MACOUPIN MADISON MARION MONROE MONTGOMERY MOULTRIE PIKE RICHLAND ST. CLAIR SHELBY VERMILION WASHINGTON WILL INC007-073-111-201720- IN . INDIANA COUNTIES INCLUDED ARE Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Tue Aug 20 2019 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FOR PARTS OF IL/IN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK ACROSS THE MIDDLE MS AND OH VALLEYS THIS AFTERNOON...NORTHERN VA AND VICINITY THIS AFTERNOON...AND PARTS OF THE CENTRAL PLAINS THIS EVENING INTO TONIGHT... ...SUMMARY... An ongoing thunderstorm cluster across Illinois will continue to pose a threat for damaging winds into this afternoon into Indiana. Damaging winds will be possible with a few storms this afternoon in the vicinity of northern Virginia. Large hail and damaging winds will be possible this evening into tonight across parts of the central Plains. ...Mid MS/OH Valley region through this afternoon... A well-developed MCS and associated MCV will continue to move east-southeastward across IL/IN through the afternoon. Convection will likely be maintained into the afternoon along the gust front as the cold pool encounters a warming boundary layer with dewpoints in the mid-upper 70s, resulting in MLCAPE in excess of 3000 J/kg with weakening convective inhibition. Vertical shear will weaken with southeastward extent aside from the MCV itself, which suggests that convective organization will be driven more by lift along the gust front by mid-late afternoon. Still, the established cold pool and potential for strong downdrafts will maintain a threat for damaging winds through the afternoon at least into IN/KY, and perhaps into OH late this afternoon. ...Northern VA and vicinity this afternoon... A small thunderstorm cluster and diffuse MCV will move eastward from the eastern WV Panhandle across northern VA/MD this afternoon. Surface heating in advance of this minor wave will contribute to moderate buoyancy (MLCAPE near 2000 J/kg), and some loose clustering of storms is expected this afternoon. Steep low-level lapse rates and DCAPE near 1000 J/kg will favor occasional downbursts with some potential for wind damage. ...Central Plains/High Plains this evening into tonight... The western extent of the outflow is effectively reinforcing a front across NE. Dry abiabatic midlevel lapse rates atop boundary-layer dewpoints in the 70s, with surface heating, will contribute to MLCAPE of 3000-4000 J/kg. Regional 12z soundings suggest that surface temperatures will need to warm to near 100-105 F to eliminate convective inhibition, thus storm formation this afternoon along the effective front is in question. The more probable scenarios are for storms to form this evening in the upslope regime near the WY/CO/NE border, and overnight across NE in the strengthening warm advection immediately north of the front. The evening upslope storms could be supercells initially as deep-layer vertical shear is augmented within the easterly low-level flow along and north of the front, and large hail would be the main concern. Some upscale growth into a cluster with damaging winds will be possible early tonight as a southerly low-level jet and warm advection strengthen. The warm advection could also support additional elevated storm development farther east across NE overnight, with an attendant threat for isolated large hail/damaging winds. ..Thompson/Coniglio.. 08/20/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Tue Aug 20 2019 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FOR PARTS OF IL/IN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK ACROSS THE MIDDLE MS AND OH VALLEYS THIS AFTERNOON...NORTHERN VA AND VICINITY THIS AFTERNOON...AND PARTS OF THE CENTRAL PLAINS THIS EVENING INTO TONIGHT... ...SUMMARY... An ongoing thunderstorm cluster across Illinois will continue to pose a threat for damaging winds into this afternoon into Indiana. Damaging winds will be possible with a few storms this afternoon in the vicinity of northern Virginia. Large hail and damaging winds will be possible this evening into tonight across parts of the central Plains. ...Mid MS/OH Valley region through this afternoon... A well-developed MCS and associated MCV will continue to move east-southeastward across IL/IN through the afternoon. Convection will likely be maintained into the afternoon along the gust front as the cold pool encounters a warming boundary layer with dewpoints in the mid-upper 70s, resulting in MLCAPE in excess of 3000 J/kg with weakening convective inhibition. Vertical shear will weaken with southeastward extent aside from the MCV itself, which suggests that convective organization will be driven more by lift along the gust front by mid-late afternoon. Still, the established cold pool and potential for strong downdrafts will maintain a threat for damaging winds through the afternoon at least into IN/KY, and perhaps into OH late this afternoon. ...Northern VA and vicinity this afternoon... A small thunderstorm cluster and diffuse MCV will move eastward from the eastern WV Panhandle across northern VA/MD this afternoon. Surface heating in advance of this minor wave will contribute to moderate buoyancy (MLCAPE near 2000 J/kg), and some loose clustering of storms is expected this afternoon. Steep low-level lapse rates and DCAPE near 1000 J/kg will favor occasional downbursts with some potential for wind damage. ...Central Plains/High Plains this evening into tonight... The western extent of the outflow is effectively reinforcing a front across NE. Dry abiabatic midlevel lapse rates atop boundary-layer dewpoints in the 70s, with surface heating, will contribute to MLCAPE of 3000-4000 J/kg. Regional 12z soundings suggest that surface temperatures will need to warm to near 100-105 F to eliminate convective inhibition, thus storm formation this afternoon along the effective front is in question. The more probable scenarios are for storms to form this evening in the upslope regime near the WY/CO/NE border, and overnight across NE in the strengthening warm advection immediately north of the front. The evening upslope storms could be supercells initially as deep-layer vertical shear is augmented within the easterly low-level flow along and north of the front, and large hail would be the main concern. Some upscale growth into a cluster with damaging winds will be possible early tonight as a southerly low-level jet and warm advection strengthen. The warm advection could also support additional elevated storm development farther east across NE overnight, with an attendant threat for isolated large hail/damaging winds. ..Thompson/Coniglio.. 08/20/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Tue Aug 20 2019 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FOR PARTS OF IL/IN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK ACROSS THE MIDDLE MS AND OH VALLEYS THIS AFTERNOON...NORTHERN VA AND VICINITY THIS AFTERNOON...AND PARTS OF THE CENTRAL PLAINS THIS EVENING INTO TONIGHT... ...SUMMARY... An ongoing thunderstorm cluster across Illinois will continue to pose a threat for damaging winds into this afternoon into Indiana. Damaging winds will be possible with a few storms this afternoon in the vicinity of northern Virginia. Large hail and damaging winds will be possible this evening into tonight across parts of the central Plains. ...Mid MS/OH Valley region through this afternoon... A well-developed MCS and associated MCV will continue to move east-southeastward across IL/IN through the afternoon. Convection will likely be maintained into the afternoon along the gust front as the cold pool encounters a warming boundary layer with dewpoints in the mid-upper 70s, resulting in MLCAPE in excess of 3000 J/kg with weakening convective inhibition. Vertical shear will weaken with southeastward extent aside from the MCV itself, which suggests that convective organization will be driven more by lift along the gust front by mid-late afternoon. Still, the established cold pool and potential for strong downdrafts will maintain a threat for damaging winds through the afternoon at least into IN/KY, and perhaps into OH late this afternoon. ...Northern VA and vicinity this afternoon... A small thunderstorm cluster and diffuse MCV will move eastward from the eastern WV Panhandle across northern VA/MD this afternoon. Surface heating in advance of this minor wave will contribute to moderate buoyancy (MLCAPE near 2000 J/kg), and some loose clustering of storms is expected this afternoon. Steep low-level lapse rates and DCAPE near 1000 J/kg will favor occasional downbursts with some potential for wind damage. ...Central Plains/High Plains this evening into tonight... The western extent of the outflow is effectively reinforcing a front across NE. Dry abiabatic midlevel lapse rates atop boundary-layer dewpoints in the 70s, with surface heating, will contribute to MLCAPE of 3000-4000 J/kg. Regional 12z soundings suggest that surface temperatures will need to warm to near 100-105 F to eliminate convective inhibition, thus storm formation this afternoon along the effective front is in question. The more probable scenarios are for storms to form this evening in the upslope regime near the WY/CO/NE border, and overnight across NE in the strengthening warm advection immediately north of the front. The evening upslope storms could be supercells initially as deep-layer vertical shear is augmented within the easterly low-level flow along and north of the front, and large hail would be the main concern. Some upscale growth into a cluster with damaging winds will be possible early tonight as a southerly low-level jet and warm advection strengthen. The warm advection could also support additional elevated storm development farther east across NE overnight, with an attendant threat for isolated large hail/damaging winds. ..Thompson/Coniglio.. 08/20/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Tue Aug 20 2019 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FOR PARTS OF IL/IN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENHANCED RISK ACROSS THE MIDDLE MS AND OH VALLEYS THIS AFTERNOON...NORTHERN VA AND VICINITY THIS AFTERNOON...AND PARTS OF THE CENTRAL PLAINS THIS EVENING INTO TONIGHT... ...SUMMARY... An ongoing thunderstorm cluster across Illinois will continue to pose a threat for damaging winds into this afternoon into Indiana. Damaging winds will be possible with a few storms this afternoon in the vicinity of northern Virginia. Large hail and damaging winds will be possible this evening into tonight across parts of the central Plains. ...Mid MS/OH Valley region through this afternoon... A well-developed MCS and associated MCV will continue to move east-southeastward across IL/IN through the afternoon. Convection will likely be maintained into the afternoon along the gust front as the cold pool encounters a warming boundary layer with dewpoints in the mid-upper 70s, resulting in MLCAPE in excess of 3000 J/kg with weakening convective inhibition. Vertical shear will weaken with southeastward extent aside from the MCV itself, which suggests that convective organization will be driven more by lift along the gust front by mid-late afternoon. Still, the established cold pool and potential for strong downdrafts will maintain a threat for damaging winds through the afternoon at least into IN/KY, and perhaps into OH late this afternoon. ...Northern VA and vicinity this afternoon... A small thunderstorm cluster and diffuse MCV will move eastward from the eastern WV Panhandle across northern VA/MD this afternoon. Surface heating in advance of this minor wave will contribute to moderate buoyancy (MLCAPE near 2000 J/kg), and some loose clustering of storms is expected this afternoon. Steep low-level lapse rates and DCAPE near 1000 J/kg will favor occasional downbursts with some potential for wind damage. ...Central Plains/High Plains this evening into tonight... The western extent of the outflow is effectively reinforcing a front across NE. Dry abiabatic midlevel lapse rates atop boundary-layer dewpoints in the 70s, with surface heating, will contribute to MLCAPE of 3000-4000 J/kg. Regional 12z soundings suggest that surface temperatures will need to warm to near 100-105 F to eliminate convective inhibition, thus storm formation this afternoon along the effective front is in question. The more probable scenarios are for storms to form this evening in the upslope regime near the WY/CO/NE border, and overnight across NE in the strengthening warm advection immediately north of the front. The evening upslope storms could be supercells initially as deep-layer vertical shear is augmented within the easterly low-level flow along and north of the front, and large hail would be the main concern. Some upscale growth into a cluster with damaging winds will be possible early tonight as a southerly low-level jet and warm advection strengthen. The warm advection could also support additional elevated storm development farther east across NE overnight, with an attendant threat for isolated large hail/damaging winds. ..Thompson/Coniglio.. 08/20/2019 Read more

WW 0602 Status Updates
STATUS REPORT ON WW 602 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 WNW IRK TO 15 SW SPI TO 15 NE BMI TO 30 NNW MMO. ..SMITH..08/20/19 ATTN...WFO...DVN...LSX...ILX...LOT...EAX... STATUS REPORT FOR WS 602 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC001-005-013-019-021-027-029-035-037-039-041-045-049-051-053- 061-063-075-083-089-091-093-099-105-107-113-115-117-119-121-133- 135-137-139-147-149-163-167-171-173-183-189-197-201630- IL . ILLINOIS COUNTIES INCLUDED ARE ADAMS BOND CALHOUN CHAMPAIGN CHRISTIAN CLINTON COLES CUMBERLAND DE KALB DE WITT DOUGLAS EDGAR EFFINGHAM FAYETTE FORD GREENE GRUNDY IROQUOIS JERSEY KANE KANKAKEE KENDALL LA SALLE LIVINGSTON LOGAN MCLEAN MACON MACOUPIN MADISON MARION MONROE MONTGOMERY MORGAN MOULTRIE PIATT PIKE ST. CLAIR SANGAMON SCOTT SHELBY VERMILION WASHINGTON WILL MOC001-007-019-027-041-071-079-089-099-103-111-113-115-121-127- Read more

MD 1809 CONCERNING SEVERE THUNDERSTORM WATCH 602... FOR MUCH OF ILLINOIS...FAR WESTERN INDIANA...AND NORTHERN MISSOURI
Mesoscale Discussion 1809 NWS Storm Prediction Center Norman OK 0904 AM CDT Tue Aug 20 2019 Areas affected...Much of Illinois...far western Indiana...and northern Missouri Concerning...Severe Thunderstorm Watch 602... Valid 201404Z - 201530Z The severe weather threat for Severe Thunderstorm Watch 602 continues. SUMMARY...A risk of widespread damaging wind gusts continues across WW 602. DISCUSSION...Damaging wind gusts remain possible area-wide this morning along and ahead of a mature bow echo now located from near MLI to IRK. More isolated convection persists ahead of this complex near MTO and west of the WW near LWD. This complex has also accelerated east-southeastward (likely due to strengthening mid-level rotation and an attendant rear-inflow jet). With a continued motion of 300/45, the leading edge of the complex should begin to approach the eastern edge of WW 602 around 1630-1730Z or so. Shear profiles are generally weak ahead of the complex, though weak to moderate instability in the pre-convective airmass and enhanced organization associated with the MCV should maintain some risk of strong to severe wind gusts and isolated hail over at least the next couple of hours or so. The severe risk downstream of WW 602 (into Indiana and northern Kentucky) will be re-evaluated around 1600Z or so as storms approach, and a new WW will be considered around that time. ..Cook.. 08/20/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LMK...IWX...IND...PAH...LOT...ILX...LSX...DVN... DMX...EAX... LAT...LON 40639296 40689221 40859168 41379133 42069080 42249029 42068905 41858787 41538695 40968636 40318620 39138646 38328706 37978791 37758878 37938959 38269021 38759098 39339233 39649328 39989364 40339383 40519374 40599333 40639296 Read more

WW 0602 Status Updates
STATUS REPORT ON WW 602 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 SW OTM TO 30 SSW BRL TO 30 NE BRL TO 20 NW MLI TO 35 ESE DBQ. ..SMITH..08/20/19 ATTN...WFO...DVN...LSX...ILX...LOT...EAX... STATUS REPORT FOR WS 602 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC001-005-009-011-013-015-017-019-021-027-029-035-037-039-041- 045-049-051-053-057-061-063-067-073-075-083-089-091-093-095-099- 103-105-107-109-113-115-117-119-121-123-125-129-131-133-135-137- 139-141-143-147-149-155-161-163-167-169-171-173-175-179-183-187- 189-195-197-203-201440- IL . ILLINOIS COUNTIES INCLUDED ARE ADAMS BOND BROWN BUREAU CALHOUN CARROLL CASS CHAMPAIGN CHRISTIAN CLINTON COLES CUMBERLAND DE KALB DE WITT DOUGLAS EDGAR EFFINGHAM FAYETTE FORD FULTON GREENE GRUNDY HANCOCK HENRY IROQUOIS JERSEY KANE KANKAKEE KENDALL KNOX LA SALLE LEE LIVINGSTON LOGAN MCDONOUGH MCLEAN MACON MACOUPIN MADISON MARION MARSHALL MASON MENARD MERCER MONROE MONTGOMERY MORGAN MOULTRIE Read more