Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0712 AM CDT Mon Aug 12 2019 Valid 121200Z - 131200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be minimal today. A mid-level trough over the northern Rockies will weaken and eject, leaving behind weaker and more zonally oriented mid-level flow across the CONUS. Mid-level flow will become minimal across dry areas of the western U.S. Outside of areas of locally elevated fire weather in Wyoming and vicinity, the quiet overall pattern indicates that no highlights will be needed for this outlook. ..Cook.. 08/12/2019 ...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 0712 AM CDT Mon Aug 12 2019 Valid 121200Z - 131200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be minimal today. A mid-level trough over the northern Rockies will weaken and eject, leaving behind weaker and more zonally oriented mid-level flow across the CONUS. Mid-level flow will become minimal across dry areas of the western U.S. Outside of areas of locally elevated fire weather in Wyoming and vicinity, the quiet overall pattern indicates that no highlights will be needed for this outlook. ..Cook.. 08/12/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0321 AM CDT Mon Aug 12 2019 Valid 151200Z - 201200Z ...DISCUSSION... Model consensus is that a low-amplitude west northwesterly flow regime with a trough in the east will reside across the northern tier states days 4-5. Upper trough will become established over the Pacific Northwest through northern Rockies days 6-7. Days 4-5 - Though predictability remains low at this range, best chance for a few severe storms will be over the central through northern Plains within a northwesterly flow regime. Here a corridor of modest low-level moisture will reside beneath steep lapse rates resulting in moderate instability. Timing of any embedded shortwave troughs and their accompanying boundaries will be difficult, but potential exists for storms to develop in this regime and spread southeast through the Plains where vertical shear and instability will be sufficient for storm organization. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0321 AM CDT Mon Aug 12 2019 Valid 151200Z - 201200Z ...DISCUSSION... Model consensus is that a low-amplitude west northwesterly flow regime with a trough in the east will reside across the northern tier states days 4-5. Upper trough will become established over the Pacific Northwest through northern Rockies days 6-7. Days 4-5 - Though predictability remains low at this range, best chance for a few severe storms will be over the central through northern Plains within a northwesterly flow regime. Here a corridor of modest low-level moisture will reside beneath steep lapse rates resulting in moderate instability. Timing of any embedded shortwave troughs and their accompanying boundaries will be difficult, but potential exists for storms to develop in this regime and spread southeast through the Plains where vertical shear and instability will be sufficient for storm organization. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0321 AM CDT Mon Aug 12 2019 Valid 151200Z - 201200Z ...DISCUSSION... Model consensus is that a low-amplitude west northwesterly flow regime with a trough in the east will reside across the northern tier states days 4-5. Upper trough will become established over the Pacific Northwest through northern Rockies days 6-7. Days 4-5 - Though predictability remains low at this range, best chance for a few severe storms will be over the central through northern Plains within a northwesterly flow regime. Here a corridor of modest low-level moisture will reside beneath steep lapse rates resulting in moderate instability. Timing of any embedded shortwave troughs and their accompanying boundaries will be difficult, but potential exists for storms to develop in this regime and spread southeast through the Plains where vertical shear and instability will be sufficient for storm organization. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0321 AM CDT Mon Aug 12 2019 Valid 151200Z - 201200Z ...DISCUSSION... Model consensus is that a low-amplitude west northwesterly flow regime with a trough in the east will reside across the northern tier states days 4-5. Upper trough will become established over the Pacific Northwest through northern Rockies days 6-7. Days 4-5 - Though predictability remains low at this range, best chance for a few severe storms will be over the central through northern Plains within a northwesterly flow regime. Here a corridor of modest low-level moisture will reside beneath steep lapse rates resulting in moderate instability. Timing of any embedded shortwave troughs and their accompanying boundaries will be difficult, but potential exists for storms to develop in this regime and spread southeast through the Plains where vertical shear and instability will be sufficient for storm organization. Read more

WW 0574 Status Updates
STATUS REPORT ON WW 574 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 WNW MHK TO 15 SSE BIE TO 10 SE LNK TO 10 NW LNK. ..KERR..08/12/19 ATTN...WFO...TOP...DDC...GLD...GID...ICT...OAX... STATUS REPORT FOR WS 574 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC117-149-161-120940- KS . KANSAS COUNTIES INCLUDED ARE MARSHALL POTTAWATOMIE RILEY NEC097-127-131-133-147-120940- NE . NEBRASKA COUNTIES INCLUDED ARE JOHNSON NEMAHA OTOE PAWNEE RICHARDSON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 574 SEVERE TSTM KS NE 120240Z - 121000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 574 NWS Storm Prediction Center Norman OK 940 PM CDT Sun Aug 11 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of North Central Kansas South-Central Nebraska * Effective this Sunday night and Monday morning from 940 PM until 500 AM CDT. ...THIS IS A PARTICULARLY DANGEROUS SITUATION... * Primary threats include... Widespread damaging winds expected with scattered significant gusts to 85 mph likely Scattered large hail and isolated very large hail events to 2 inches in diameter possible A couple tornadoes possible SUMMARY...A developing bow echo over northwest Kansas will move rapidly eastward overnight, posing a risk of widespread damaging wind gusts across the watch area. Large hail and a tornado or two are also possible. The severe thunderstorm watch area is approximately along and 60 statute miles north and south of a line from 40 miles northwest of Hill City KS to 15 miles south southeast of Beatrice NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 571...WW 572...WW 573... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 75 knots. A few cumulonimbi with maximum tops to 600. Mean storm motion vector 26040. ...Hart Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Aug 12 2019 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE SOUTHEAST STATES AND CENTRAL HIGH PLAINS... ...SUMMARY... A few strong to severe storms with isolated damaging wind will be possible over the southeast states Wednesday afternoon. Isolated strong to severe storms will also be possible over a portion of the central High Plains. ...Synopsis... Trend will be for synoptic upper trough to amplify over the eastern U.S. Wednesday with subtropical high building into the southwestern states. At the start of the period a cold front will stretch from eastern NC southwest through the southeast states into central TX and this boundary will advance slowly southeast during the day. ...Southeast States... Rich low-level moisture with 70s F dewpoints will reside in pre-frontal warm sector supporting moderate to strong instability as the surface layer warms with 2000-3000 J/kg MLCAPE expected. Storms should develop within the weakly capped environment along the front by early afternoon and spread southeast. The moist warm sector will have been shunted well south of the stronger westerlies with weak winds aloft supportive of pulse and multicell storms, possibly evolving into line segments along the front. Isolated downburst winds will be the main threat through early evening. ...Central High Plains... A corridor of low 60s F dewpoints will reside over the central High Plains beneath steep lapse rates supporting 1500-2000 J/kg MLCAPE. This region will remain within a belt of moderate northwesterly winds aloft with 35-45 kt effective bulk shear. Background forcing is expected to remain weak, but isolated storms may develop over the higher terrain and spread southeast as well as along a lee trough. The environment will conditionally support a threat for supercells capable of large hail and downburst winds and have therefore introduced a MRGL risk category. If it begins to appear storm coverage will be greater than currently anticipated, then a SLGT risk might be needed in later outlooks. ..Dial.. 08/12/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Aug 12 2019 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE SOUTHEAST STATES AND CENTRAL HIGH PLAINS... ...SUMMARY... A few strong to severe storms with isolated damaging wind will be possible over the southeast states Wednesday afternoon. Isolated strong to severe storms will also be possible over a portion of the central High Plains. ...Synopsis... Trend will be for synoptic upper trough to amplify over the eastern U.S. Wednesday with subtropical high building into the southwestern states. At the start of the period a cold front will stretch from eastern NC southwest through the southeast states into central TX and this boundary will advance slowly southeast during the day. ...Southeast States... Rich low-level moisture with 70s F dewpoints will reside in pre-frontal warm sector supporting moderate to strong instability as the surface layer warms with 2000-3000 J/kg MLCAPE expected. Storms should develop within the weakly capped environment along the front by early afternoon and spread southeast. The moist warm sector will have been shunted well south of the stronger westerlies with weak winds aloft supportive of pulse and multicell storms, possibly evolving into line segments along the front. Isolated downburst winds will be the main threat through early evening. ...Central High Plains... A corridor of low 60s F dewpoints will reside over the central High Plains beneath steep lapse rates supporting 1500-2000 J/kg MLCAPE. This region will remain within a belt of moderate northwesterly winds aloft with 35-45 kt effective bulk shear. Background forcing is expected to remain weak, but isolated storms may develop over the higher terrain and spread southeast as well as along a lee trough. The environment will conditionally support a threat for supercells capable of large hail and downburst winds and have therefore introduced a MRGL risk category. If it begins to appear storm coverage will be greater than currently anticipated, then a SLGT risk might be needed in later outlooks. ..Dial.. 08/12/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Aug 12 2019 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE SOUTHEAST STATES AND CENTRAL HIGH PLAINS... ...SUMMARY... A few strong to severe storms with isolated damaging wind will be possible over the southeast states Wednesday afternoon. Isolated strong to severe storms will also be possible over a portion of the central High Plains. ...Synopsis... Trend will be for synoptic upper trough to amplify over the eastern U.S. Wednesday with subtropical high building into the southwestern states. At the start of the period a cold front will stretch from eastern NC southwest through the southeast states into central TX and this boundary will advance slowly southeast during the day. ...Southeast States... Rich low-level moisture with 70s F dewpoints will reside in pre-frontal warm sector supporting moderate to strong instability as the surface layer warms with 2000-3000 J/kg MLCAPE expected. Storms should develop within the weakly capped environment along the front by early afternoon and spread southeast. The moist warm sector will have been shunted well south of the stronger westerlies with weak winds aloft supportive of pulse and multicell storms, possibly evolving into line segments along the front. Isolated downburst winds will be the main threat through early evening. ...Central High Plains... A corridor of low 60s F dewpoints will reside over the central High Plains beneath steep lapse rates supporting 1500-2000 J/kg MLCAPE. This region will remain within a belt of moderate northwesterly winds aloft with 35-45 kt effective bulk shear. Background forcing is expected to remain weak, but isolated storms may develop over the higher terrain and spread southeast as well as along a lee trough. The environment will conditionally support a threat for supercells capable of large hail and downburst winds and have therefore introduced a MRGL risk category. If it begins to appear storm coverage will be greater than currently anticipated, then a SLGT risk might be needed in later outlooks. ..Dial.. 08/12/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Aug 12 2019 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE SOUTHEAST STATES AND CENTRAL HIGH PLAINS... ...SUMMARY... A few strong to severe storms with isolated damaging wind will be possible over the southeast states Wednesday afternoon. Isolated strong to severe storms will also be possible over a portion of the central High Plains. ...Synopsis... Trend will be for synoptic upper trough to amplify over the eastern U.S. Wednesday with subtropical high building into the southwestern states. At the start of the period a cold front will stretch from eastern NC southwest through the southeast states into central TX and this boundary will advance slowly southeast during the day. ...Southeast States... Rich low-level moisture with 70s F dewpoints will reside in pre-frontal warm sector supporting moderate to strong instability as the surface layer warms with 2000-3000 J/kg MLCAPE expected. Storms should develop within the weakly capped environment along the front by early afternoon and spread southeast. The moist warm sector will have been shunted well south of the stronger westerlies with weak winds aloft supportive of pulse and multicell storms, possibly evolving into line segments along the front. Isolated downburst winds will be the main threat through early evening. ...Central High Plains... A corridor of low 60s F dewpoints will reside over the central High Plains beneath steep lapse rates supporting 1500-2000 J/kg MLCAPE. This region will remain within a belt of moderate northwesterly winds aloft with 35-45 kt effective bulk shear. Background forcing is expected to remain weak, but isolated storms may develop over the higher terrain and spread southeast as well as along a lee trough. The environment will conditionally support a threat for supercells capable of large hail and downburst winds and have therefore introduced a MRGL risk category. If it begins to appear storm coverage will be greater than currently anticipated, then a SLGT risk might be needed in later outlooks. ..Dial.. 08/12/2019 Read more

WW 0574 Status Updates
STATUS REPORT ON WW 574 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 NE RSL TO 35 SSE HSI TO 25 SE HSI TO 30 SSW EAR TO 20 W EAR. ..KERR..08/12/19 ATTN...WFO...TOP...DDC...GLD...GID...ICT...OAX... STATUS REPORT FOR WS 574 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS KSC027-029-089-105-123-143-157-201-120740- KS . KANSAS COUNTIES INCLUDED ARE CLAY CLOUD JEWELL LINCOLN MITCHELL OTTAWA REPUBLIC WASHINGTON NEC001-019-035-059-067-079-081-093-095-099-109-121-129-143-151- 159-163-169-185-120740- NE . NEBRASKA COUNTIES INCLUDED ARE ADAMS BUFFALO CLAY FILLMORE GAGE HALL HAMILTON HOWARD JEFFERSON KEARNEY LANCASTER MERRICK NUCKOLLS POLK SALINE SEWARD SHERMAN THAYER YORK Read more

MD 1713 CONCERNING SEVERE THUNDERSTORM WATCH 574... FOR NORTHEAST KANSAS AND SOUTHEAST NEBRASKA INTO NORTHWEST MISSOURI AND SOUTHEAST IOWA
Mesoscale Discussion 1713 NWS Storm Prediction Center Norman OK 0115 AM CDT Mon Aug 12 2019 Areas affected...Northeast Kansas and southeast Nebraska into northwest Missouri and southeast Iowa Concerning...Severe Thunderstorm Watch 574... Valid 120615Z - 120745Z The severe weather threat for Severe Thunderstorm Watch 574 continues. SUMMARY...Thunderstorm activity posing at least some continuing risk for potentially damaging surface gusts probably will continue through daybreak. A new severe thunderstorm watch likely will be issued east of severe thunderstorm watch 574 within the next hour or so. DISCUSSION...Vigorous convective development persists and continues to spread northeastward and eastward across parts of southern Nebraska and northern Kansas, accompanied by occasional strong to severe wind gusts. Strongest gusts have recently been focused near a lower/mid tropospheric cyclonic vorticity center now migrating across the Kearney NE area, and along the leading edge of the stronger/deeper portion of the surface cold pool approaching the Concordia KS and Hebron NE areas. North and east of a weak warm front, extending from its intersection with the cold pool, roughly near the state border, east southeastward into the Interstate 70 corridor of northeast Kansas, inflow of somewhat cooler and more stable boundary layer air may weaken convection during the next few hours as it approaches the Missouri River. Maintenance of strong thunderstorm development seems most likely in closer proximity to the warm front, where forcing for ascent associated with warm advection, on the nose of a 30-50 kt low-level jet, will become focused by 3-5 AM, as the jet gradually continues to veer from southerly to southwesterly. High moisture content concentrated along the front is contributing to large CAPE of 2000-4000 J/kg, in the presence of strong deep layer shear (largely due to veering of wind fields with height). Within this regime, the evolution of another organizing cluster on the southern flank of the ongoing activity appears possible. ..Kerr.. 08/12/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...EAX...OAX...TOP...GID... LAT...LON 40379727 41009806 40809531 39709427 39009472 38869618 39079736 40379727 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE MIDDLE ATLANTIC REGION... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into southern portion of the Ohio Valley. Other strong to severe storms are possible over the Tennessee Valley and the central High Plains. ...Middle Atlantic and southern Ohio Valley regions... A convectively enhanced vorticity maximum embedded within a broad upper trough should reach OH by 12Z Tuesday, and this feature will continue east into the Northeast States and the northern portion of the Mid Atlantic during the day. At the start of the period a cold front will extend from a weak low over IN southwestward into northern TX. A warm or stationary front will stretch eastward from the low into southern PA. Storms will likely be ongoing from OH to western PA within zone of isentropic ascent north of stationary front. South of this activity, diabatic warming of the moistening surface layer will result in moderate instability with 1500-2000 J/kg MLCAPE expected. Additional storms should develop by late morning or afternoon in vicinity of the warm front across southern PA and northern VA, as well as farther south and west over the higher terrain and spread eastward into the warm sector. The NAM indicates the strongest kinematic environment, but might be overdone with convective feedback. Nevertheless, this region will reside within belt of moderate westerlies with 30-40 kt effective bulk shear supportive of organized storms including supercells. If enough destabilization can occur along the warm front, low-level hodographs may become supportive of a few tornadoes. Otherwise damaging wind will be the main threat. Other storms are expected to develop along southwestern extension of the cold front, especially from KY into the TN Valley during the afternoon where both the thermodynamic and kinematic parameter space should support mostly multicells and line segments with damaging wind the main threats. ...Central High Plains... A few storms are expected to develop along a lee trough and higher terrain within an evolving easterly post-frontal regime across the central High Plains. Modest low-level moisture beneath steep lapse rates will support up to 2000 j/kg MLCAPE, and this region will reside within belt of modest northwesterly winds aloft with 30-35 effective bulk shear. This environment may support a few instances of large hail and strong wind gusts before activity weakens by mid evening. Due to uncertainties regarding storm coverage will leave MRGL this update, but this region will continue to be monitored for a possible SLGT risk in later outlooks. ...Upper Mississippi Valley region... Isolated storms may develop over the upper Midwest in association with a southeast-advancing shortwave trough and within a weakly unstable environment. A belt of stronger unidirectional winds aloft will support up to 40 kt effective bulk shear. A few storms could produce locally strong wind gusts and hail, but overall threat should remain marginal. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Dial.. 08/12/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE MIDDLE ATLANTIC REGION... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into southern portion of the Ohio Valley. Other strong to severe storms are possible over the Tennessee Valley and the central High Plains. ...Middle Atlantic and southern Ohio Valley regions... A convectively enhanced vorticity maximum embedded within a broad upper trough should reach OH by 12Z Tuesday, and this feature will continue east into the Northeast States and the northern portion of the Mid Atlantic during the day. At the start of the period a cold front will extend from a weak low over IN southwestward into northern TX. A warm or stationary front will stretch eastward from the low into southern PA. Storms will likely be ongoing from OH to western PA within zone of isentropic ascent north of stationary front. South of this activity, diabatic warming of the moistening surface layer will result in moderate instability with 1500-2000 J/kg MLCAPE expected. Additional storms should develop by late morning or afternoon in vicinity of the warm front across southern PA and northern VA, as well as farther south and west over the higher terrain and spread eastward into the warm sector. The NAM indicates the strongest kinematic environment, but might be overdone with convective feedback. Nevertheless, this region will reside within belt of moderate westerlies with 30-40 kt effective bulk shear supportive of organized storms including supercells. If enough destabilization can occur along the warm front, low-level hodographs may become supportive of a few tornadoes. Otherwise damaging wind will be the main threat. Other storms are expected to develop along southwestern extension of the cold front, especially from KY into the TN Valley during the afternoon where both the thermodynamic and kinematic parameter space should support mostly multicells and line segments with damaging wind the main threats. ...Central High Plains... A few storms are expected to develop along a lee trough and higher terrain within an evolving easterly post-frontal regime across the central High Plains. Modest low-level moisture beneath steep lapse rates will support up to 2000 j/kg MLCAPE, and this region will reside within belt of modest northwesterly winds aloft with 30-35 effective bulk shear. This environment may support a few instances of large hail and strong wind gusts before activity weakens by mid evening. Due to uncertainties regarding storm coverage will leave MRGL this update, but this region will continue to be monitored for a possible SLGT risk in later outlooks. ...Upper Mississippi Valley region... Isolated storms may develop over the upper Midwest in association with a southeast-advancing shortwave trough and within a weakly unstable environment. A belt of stronger unidirectional winds aloft will support up to 40 kt effective bulk shear. A few storms could produce locally strong wind gusts and hail, but overall threat should remain marginal. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Dial.. 08/12/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE MIDDLE ATLANTIC REGION... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into southern portion of the Ohio Valley. Other strong to severe storms are possible over the Tennessee Valley and the central High Plains. ...Middle Atlantic and southern Ohio Valley regions... A convectively enhanced vorticity maximum embedded within a broad upper trough should reach OH by 12Z Tuesday, and this feature will continue east into the Northeast States and the northern portion of the Mid Atlantic during the day. At the start of the period a cold front will extend from a weak low over IN southwestward into northern TX. A warm or stationary front will stretch eastward from the low into southern PA. Storms will likely be ongoing from OH to western PA within zone of isentropic ascent north of stationary front. South of this activity, diabatic warming of the moistening surface layer will result in moderate instability with 1500-2000 J/kg MLCAPE expected. Additional storms should develop by late morning or afternoon in vicinity of the warm front across southern PA and northern VA, as well as farther south and west over the higher terrain and spread eastward into the warm sector. The NAM indicates the strongest kinematic environment, but might be overdone with convective feedback. Nevertheless, this region will reside within belt of moderate westerlies with 30-40 kt effective bulk shear supportive of organized storms including supercells. If enough destabilization can occur along the warm front, low-level hodographs may become supportive of a few tornadoes. Otherwise damaging wind will be the main threat. Other storms are expected to develop along southwestern extension of the cold front, especially from KY into the TN Valley during the afternoon where both the thermodynamic and kinematic parameter space should support mostly multicells and line segments with damaging wind the main threats. ...Central High Plains... A few storms are expected to develop along a lee trough and higher terrain within an evolving easterly post-frontal regime across the central High Plains. Modest low-level moisture beneath steep lapse rates will support up to 2000 j/kg MLCAPE, and this region will reside within belt of modest northwesterly winds aloft with 30-35 effective bulk shear. This environment may support a few instances of large hail and strong wind gusts before activity weakens by mid evening. Due to uncertainties regarding storm coverage will leave MRGL this update, but this region will continue to be monitored for a possible SLGT risk in later outlooks. ...Upper Mississippi Valley region... Isolated storms may develop over the upper Midwest in association with a southeast-advancing shortwave trough and within a weakly unstable environment. A belt of stronger unidirectional winds aloft will support up to 40 kt effective bulk shear. A few storms could produce locally strong wind gusts and hail, but overall threat should remain marginal. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Dial.. 08/12/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE MIDDLE ATLANTIC REGION... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into southern portion of the Ohio Valley. Other strong to severe storms are possible over the Tennessee Valley and the central High Plains. ...Middle Atlantic and southern Ohio Valley regions... A convectively enhanced vorticity maximum embedded within a broad upper trough should reach OH by 12Z Tuesday, and this feature will continue east into the Northeast States and the northern portion of the Mid Atlantic during the day. At the start of the period a cold front will extend from a weak low over IN southwestward into northern TX. A warm or stationary front will stretch eastward from the low into southern PA. Storms will likely be ongoing from OH to western PA within zone of isentropic ascent north of stationary front. South of this activity, diabatic warming of the moistening surface layer will result in moderate instability with 1500-2000 J/kg MLCAPE expected. Additional storms should develop by late morning or afternoon in vicinity of the warm front across southern PA and northern VA, as well as farther south and west over the higher terrain and spread eastward into the warm sector. The NAM indicates the strongest kinematic environment, but might be overdone with convective feedback. Nevertheless, this region will reside within belt of moderate westerlies with 30-40 kt effective bulk shear supportive of organized storms including supercells. If enough destabilization can occur along the warm front, low-level hodographs may become supportive of a few tornadoes. Otherwise damaging wind will be the main threat. Other storms are expected to develop along southwestern extension of the cold front, especially from KY into the TN Valley during the afternoon where both the thermodynamic and kinematic parameter space should support mostly multicells and line segments with damaging wind the main threats. ...Central High Plains... A few storms are expected to develop along a lee trough and higher terrain within an evolving easterly post-frontal regime across the central High Plains. Modest low-level moisture beneath steep lapse rates will support up to 2000 j/kg MLCAPE, and this region will reside within belt of modest northwesterly winds aloft with 30-35 effective bulk shear. This environment may support a few instances of large hail and strong wind gusts before activity weakens by mid evening. Due to uncertainties regarding storm coverage will leave MRGL this update, but this region will continue to be monitored for a possible SLGT risk in later outlooks. ...Upper Mississippi Valley region... Isolated storms may develop over the upper Midwest in association with a southeast-advancing shortwave trough and within a weakly unstable environment. A belt of stronger unidirectional winds aloft will support up to 40 kt effective bulk shear. A few storms could produce locally strong wind gusts and hail, but overall threat should remain marginal. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Dial.. 08/12/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE MIDDLE ATLANTIC REGION... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into southern portion of the Ohio Valley. Other strong to severe storms are possible over the Tennessee Valley and the central High Plains. ...Middle Atlantic and southern Ohio Valley regions... A convectively enhanced vorticity maximum embedded within a broad upper trough should reach OH by 12Z Tuesday, and this feature will continue east into the Northeast States and the northern portion of the Mid Atlantic during the day. At the start of the period a cold front will extend from a weak low over IN southwestward into northern TX. A warm or stationary front will stretch eastward from the low into southern PA. Storms will likely be ongoing from OH to western PA within zone of isentropic ascent north of stationary front. South of this activity, diabatic warming of the moistening surface layer will result in moderate instability with 1500-2000 J/kg MLCAPE expected. Additional storms should develop by late morning or afternoon in vicinity of the warm front across southern PA and northern VA, as well as farther south and west over the higher terrain and spread eastward into the warm sector. The NAM indicates the strongest kinematic environment, but might be overdone with convective feedback. Nevertheless, this region will reside within belt of moderate westerlies with 30-40 kt effective bulk shear supportive of organized storms including supercells. If enough destabilization can occur along the warm front, low-level hodographs may become supportive of a few tornadoes. Otherwise damaging wind will be the main threat. Other storms are expected to develop along southwestern extension of the cold front, especially from KY into the TN Valley during the afternoon where both the thermodynamic and kinematic parameter space should support mostly multicells and line segments with damaging wind the main threats. ...Central High Plains... A few storms are expected to develop along a lee trough and higher terrain within an evolving easterly post-frontal regime across the central High Plains. Modest low-level moisture beneath steep lapse rates will support up to 2000 j/kg MLCAPE, and this region will reside within belt of modest northwesterly winds aloft with 30-35 effective bulk shear. This environment may support a few instances of large hail and strong wind gusts before activity weakens by mid evening. Due to uncertainties regarding storm coverage will leave MRGL this update, but this region will continue to be monitored for a possible SLGT risk in later outlooks. ...Upper Mississippi Valley region... Isolated storms may develop over the upper Midwest in association with a southeast-advancing shortwave trough and within a weakly unstable environment. A belt of stronger unidirectional winds aloft will support up to 40 kt effective bulk shear. A few storms could produce locally strong wind gusts and hail, but overall threat should remain marginal. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Dial.. 08/12/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1235 AM CDT Mon Aug 12 2019 Valid 121200Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST IA TO CENTRAL IL... ...SUMMARY... Severe thunderstorms are likely today over the middle Mississippi Valley to the Ohio Valley. Damaging gusts are the primary risk but a few tornadoes are possible. ...Mid MS/OH Valley Region... An impressive amount of deep convection has developed over the central Plains early this morning ahead of a disturbance that should approach western IA by sunrise. A reservoir of untapped buoyancy currently extends ahead of the MCS over eastern KS which should aid eastward progression of organized convection into the beginning of the upcoming day1 period. Latest NAM model guidance suggests leading edge of this activity will be near the MO River at sunrise; however, current speed/movement of the convection is considerably faster and storms could advance into western IA by 09z. It's not entirely clear whether the MCS will slow its forward propagation so confidence in timing/placement of this complex of storms is somewhat in doubt. Current outlook is predicated on MCS slowing a bit toward sunrise. For these reasons have adjusted severe probs west across IA/northern MO to account for possible severe at the beginning of the period. If boundary layer is able to warm/destabilize ahead of this activity, as NAM currently depicts, environmental parameters would seem supportive of organized convection continuing downstream, with some upward evolution expected by late morning. If convection maintains MCS structure then damaging winds will be the primary threat. However, forecast soundings across southeast IA into west-central IL exhibit favorable CAPE/shear for supercells and possible tornadoes. Will introduce low tornado probs to account for possible discrete updrafts by early afternoon. ...Eastern Dakotas... Early-morning water-vapor imagery depicts a well-defined short-wave trough over MT/WY shifting east toward the northern Plains. This feature is forecast to advance into the western Dakotas by 13/00z where it should aid scattered convection along/ahead of progressive wind shift. Hail/wind are the primary risks with scattered storms later today. ...ME... Weak mid-level height falls are forecast to spread south across ME later Monday. Deep westerly flow should allow boundary layer to warm such that inhibition is removed by 17z ahead of a zone of weak low-level confluence. Isolated thunderstorms are expected to develop across northern New England within a flow regime that could support storm organization capable of producing isolated damaging wind gusts. ..Darrow/Cook.. 08/12/2019 Read more