WW 611 SEVERE TSTM CO KS NE WY 072015Z - 080400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 611 NWS Storm Prediction Center Norman OK 215 PM MDT Wed Aug 7 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Colorado Far Northwest Kansas Western Nebraska Far Southeast Wyoming * Effective this Wednesday afternoon and evening from 215 PM until 1000 PM MDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Scattered large hail and isolated very large hail events to 2 inches in diameter possible SUMMARY...Thunderstorm development is expected to continue across the southeastern Wyoming and northeastern Colorado, with these storms then moving downstream into western Nebraska and far northwest Kansas. The environment supports large hail with the early, more cellular storms, with a trend towards a more linear mode anticipated thereafter. Damaging gusts are the more likely threat as the line of storms moves into western Nebraska and far northwest Kansas. The severe thunderstorm watch area is approximately along and 65 statute miles north and south of a line from 25 miles south southwest of Cheyenne WY to Mccook NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). 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 610... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27035. ...Mosier Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Wed Aug 07 2024 Valid 072000Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL PLAINS...AND COASTAL NC/SC.... ...SUMMARY... Strong to severe thunderstorms capable of damaging gusts are possible across the central High Plains this afternoon and evening. A few tornadoes remain possible today and tonight across the coastal Carolinas. The only change for this outlook update is to add a small area of SLGT risk for parts of coastal NC/SC. Isolated tornadoes have occurred this afternoon over parts of these areas, and the potential exists for further development of semi-discrete cells offshore that rotate inland. Shear profiles remain sufficiently strong to support further tornado risk. Please refer to MCD #1858 and WW #610 for further details. ..Hart.. 08/07/2024 .PREV DISCUSSION... /ISSUED 1121 AM CDT Wed Aug 07 2024/ ...Synopsis... Expansive upper ridging will continue across the Southeast and southern Plains today, although some dampening is possible along its northern/northeastern periphery. This dampening will occur as a series of shortwave troughs rotate through the base of the upper troughing extending from the Hudson Bay into the Pacific Northwest. Lead shortwave trough in this series is currently moving across the northern Plains, with another shortwave farther west across the northern Rockies. Eastward progression of the lead shortwave trough will encourage an associated eastward/southeastward push of the cold front that currently extends from far northwestern Ontario into east-central WY. Thunderstorm development is anticipated along this front from the eastern Dakotas and MN into NE. Low-level upslope flow into the central High Plains will also support thunderstorms ahead of this cold front from southwest WY/eastern CO into the central Plains. Farther east, Tropical Storm Debby remain centered off the SC Coast. Steering currents remain weak in its vicinity, with only modest northwesterly progress anticipated throughout much of the period. See latest NHC advisories for track/intensity forecasts for Debby, as well as tropical watches/warnings. ...Central High Plains/Central Plains... Southeasterly low-level, upslope flow will help maintain at least moderate low-level moisture amid strong boundary-layer mixing this afternoon across the central High Plains. General expectation is for dewpoints to be in the mid/upper 50s by 21Z, which should be sufficient for air mass destabilization as temperatures warm into the mid 90s. Glancing ascent from the shortwave trough moving through northern Rockies coupled with orographic effects is expected to result in thunderstorm development across the high terrain, with these storms then moving into the moderately buoyant and sheared airmass downstream. Given the moderate shear (i.e. 0-6 around 40 kt), some more organized and persistent updrafts are possible. High cloud bases and steep low-level lapse rates will also support strong downdrafts with these more persistent storms. Given the close storm proximity and high coverage, there is some chance for cold pool amalgamation, with resulting downstream propagation into more of the central High Plains. Additionally, interaction with the frontal boundary could augment updrafts while also providing a corridor of greater severe-wind potential. Potential for damaging gusts appears high enough to introduce a 15% area from far northeast CO/NE Panhandle southeastward into southwest NE and far northwest KS. Some isolated hail is possible, both with initial development in the vicinity of the high terrain as well as any post-frontal development across the central High Plains. Isolated hail is also possible with any initial development along the front farther east from far southwest MN/southeast SD into central NE. ...Coastal Carolinas/TS Debby... As mentioned in MCD #1857, the near-term tornado risk along the coastal Carolinas associated with Debby is low, owing to limited destabilization and poor low-level lapse rates. Even so, rain bands will continue to wrap around the system throughout the day, and, given the strong low-level shear in place, any deeper, more persistent convective cores may be able to produce tornadoes. A relatively greater (but still quite low) threat may be able to develop across the Outer Banks vicinity if pockets of heating can occur within any cloud breaks. As the system gradually moves northwestward tonight, the loss of daytime heating suggests the tornado threat may become more confined closer to the center of the system over coastal northeast SC and coastal southern NC. Read more

WW 0610 Status Updates
STATUS FOR WATCH 0610 HAS NOT BEEN ISSUED YET Read more

WW 610 TORNADO NC SC CW 072000Z - 080300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 610 NWS Storm Prediction Center Norman OK 400 PM EDT Wed Aug 7 2024 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southern Coastal North Carolina Far Northern Coastal South Carolina Coastal Waters * Effective this Wednesday afternoon and evening from 400 PM until 1100 PM EDT. * Primary threats include... A couple tornadoes possible SUMMARY...Rain bands continue to rotate around Tropical Storm Debby. A few stronger thunderstorms with the potential to produce brief tornadoes are possible within these bands. The tornado watch area is approximately along and 30 statute miles north and south of a line from 15 miles west southwest of Myrtle Beach SC to 25 miles southeast of New Bern NC. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 14030. ...Mosier Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Wed Aug 07 2024 Valid 081200Z - 091200Z The previous forecast is largely on track. The Isolated Dry Thunder area was expanded to account for drier conditions across parts of western Colorado with receptive fuels in the region. Otherwise, see the previous discussion for further details. ..Supinie.. 08/07/2024 .PREV DISCUSSION... /ISSUED 0150 AM CDT Wed Aug 07 2024/ ...Synopsis... A trough moving across the northern Rockies into the northern Plains will suppress the western US ridge on Thursday. Flow aloft will shift to become more northwesterly, with monsoonal moisture shifting southward. Isolated dry thunderstorm chances will be possible along the fringes of the deeper monsoonal moisture across southern/central Utah into western Colorado and western Wyoming. In this region, precipitable water values around 0.50-0.75 inch and mainly mid-level moisture will result in high-based convection, with potential for new ignitions amid receptive fuels, and little precipitation. Gusty and erratic winds will be possible near thunderstorms. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1858 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF COASTAL NORTH CAROLINA
Mesoscale Discussion 1858 NWS Storm Prediction Center Norman OK 0117 PM CDT Wed Aug 07 2024 Areas affected...portions of coastal North Carolina Concerning...Severe potential...Watch unlikely Valid 071817Z - 072045Z Probability of Watch Issuance...20 percent SUMMARY...A couple of tornadoes are possible this afternoon with the more organized storms embedded in the rainbands of Debby. The overall severe threat should remain isolated and a WW issuance is not anticipated. DISCUSSION...Modest surface heating has allowed for surface temperatures to warm to the 79-81 F mark about 50 miles inland from the coast. The LTX VAD profiler has recently shown over 300 m2/s2 0-1 km SRH in the vicinity of where low-topped supercells are ongoing (southern NC coastline). As such, kinematics and current storm mode does favor tornado production. However, boundary-layer lapse rates remain poor (i.e. 5-5.5 C/km), so the instability needed for low-level vorticity stretching is marginal at best. As such, any tornadoes that manage to form should be brief and a WW issuance is not expected. ..Squitieri/Mosier.. 08/07/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MHX...RAH...ILM... LAT...LON 33837850 34527843 35307770 35737641 35727559 35467540 35077566 34637642 34367715 33877786 33837850 Read more

MD 1859 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF THE CENTRAL HIGH PLAINS
Mesoscale Discussion 1859 NWS Storm Prediction Center Norman OK 0157 PM CDT Wed Aug 07 2024 Areas affected...portions of the central High Plains Concerning...Severe potential...Watch possible Valid 071857Z - 072100Z Probability of Watch Issuance...60 percent SUMMARY...Scattered strong to severe storms are expected early this afternoon across the higher terrain of eastern WY and CO. A mix of supercells and clusters may produce damaging winds and hail. A WW is being considered. DISCUSSION...As of 1845 UTC, regional visible and radar imagery showed initial thunderstorm development was ongoing over southern Laramie Range in eastern WY with additional storms developing over parts of northern CO. Further development and maturation of convection is expected over the next couple of hours as ascent from a subtle shortwave trough overspreads the central Rockies. Weak upslope flow and the approach of a cold front from the north will continue to advect seasonable low-level moisture (upper 50s to low 60s F dewpoints) across the central High Plains. While currently MLCINH is still robust, continued heating, the approach of the front and upslope should gradually support destabilization with 1000-1500 J/kg of MLCAPE expected. 35-40 kt of deep-layer shear will support storm organization with a mix of multi-cell clusters and supercells possible. Steep low and mid-level lapse rates will support strong downdrafts capable of damaging gusts, especially with any persistent clusters. Hail (some could be as large as 2 in) will also be possible, especially with any supercell structures. The initial ongoing storms are, so far, closely tied to the terrain where more persistent orographic ascent has removed most inhibition. As the capping over the plains is slowly removed these initial updrafts should move eastward across parts of northeast CO and eastern WY into western NE. CAM guidance varies on the timing of this transition, but observation trends suggest this could occur as early as the next hour or two. While confidence in the exact timing of the increasing severe risk is low, the potential for damaging wind gusts and hail suggest a watch may be needed. ..Lyons/Mosier.. 08/07/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...BOU...CYS... LAT...LON 39170390 39470450 40010487 40610516 42020551 42720500 42760479 42580250 42300186 41980135 41690110 41020064 40490060 39390142 39120244 39080300 39170390 Read more

No watches are valid as of Wed Aug 7 19:00:01 UTC 2024.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1220 PM CDT Wed Aug 07 2024 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ON THURSDAY ACROSS PORTIONS OF CENTRAL AND EASTERN NORTH CAROLINA AND SOUTH-CENTRAL VIRGINIA... ...SUMMARY... Thunderstorms developing Thursday across the coastal plain of eastern North Carolina through southern Virginia may be accompanied by potential for a few tornadoes, as Debby moves inland across the south Atlantic coast. ...NC/VA... Debby will likely remain a Tropical Storm as the system tracks northward across the Carolinas on Thursday. Strong southeasterly low-level winds in the eastern semi-circle will result in favorable shear profiles for a few tornadoes. So far with this system, a lack of heating in the more strongly sheared areas has limited overall tornado potential. However, 12z CAM solutions suggest the potential for more heating across parts of central NC and southern VA tomorrow, lending some concern for an uptick in risk. ...Southwest... Scattered or greater coverage of thunderstorms is expected on Thursday across much of the southern Rockies, southern Great Basin, and Four Corners regions. Pockets of strong daytime heating and steep lapse rates will result in the potential for damaging wind gusts in some areas, although confidence in the mesoscale details of these risk areas is low at this time. Portions of this region may need an upgrade to MRGL risk in subsequent outlook updates. ..Hart.. 08/07/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Wed Aug 07 2024 Valid 071630Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Strong to severe thunderstorms capable of damaging gusts are possible across the central High Plains this afternoon and evening. A few tornadoes remain possible today and tonight across the coastal Carolinas. ...Synopsis... Expansive upper ridging will continue across the Southeast and southern Plains today, although some dampening is possible along its northern/northeastern periphery. This dampening will occur as a series of shortwave troughs rotate through the base of the upper troughing extending from the Hudson Bay into the Pacific Northwest. Lead shortwave trough in this series is currently moving across the northern Plains, with another shortwave farther west across the northern Rockies. Eastward progression of the lead shortwave trough will encourage an associated eastward/southeastward push of the cold front that currently extends from far northwestern Ontario into east-central WY. Thunderstorm development is anticipated along this front from the eastern Dakotas and MN into NE. Low-level upslope flow into the central High Plains will also support thunderstorms ahead of this cold front from southwest WY/eastern CO into the central Plains. Farther east, Tropical Storm Debby remain centered off the SC Coast. Steering currents remain weak in its vicinity, with only modest northwesterly progress anticipated throughout much of the period. See latest NHC advisories for track/intensity forecasts for Debby, as well as tropical watches/warnings. ...Central High Plains/Central Plains... Southeasterly low-level, upslope flow will help maintain at least moderate low-level moisture amid strong boundary-layer mixing this afternoon across the central High Plains. General expectation is for dewpoints to be in the mid/upper 50s by 21Z, which should be sufficient for air mass destabilization as temperatures warm into the mid 90s. Glancing ascent from the shortwave trough moving through northern Rockies coupled with orographic effects is expected to result in thunderstorm development across the high terrain, with these storms then moving into the moderately buoyant and sheared airmass downstream. Given the moderate shear (i.e. 0-6 around 40 kt), some more organized and persistent updrafts are possible. High cloud bases and steep low-level lapse rates will also support strong downdrafts with these more persistent storms. Given the close storm proximity and high coverage, there is some chance for cold pool amalgamation, with resulting downstream propagation into more of the central High Plains. Additionally, interaction with the frontal boundary could augment updrafts while also providing a corridor of greater severe-wind potential. Potential for damaging gusts appears high enough to introduce a 15% area from far northeast CO/NE Panhandle southeastward into southwest NE and far northwest KS. Some isolated hail is possible, both with initial development in the vicinity of the high terrain as well as any post-frontal development across the central High Plains. Isolated hail is also possible with any initial development along the front farther east from far southwest MN/southeast SD into central NE. ...Coastal Carolinas/TS Debby... As mentioned in MCD #1857, the near-term tornado risk along the coastal Carolinas associated with Debby is low, owing to limited destabilization and poor low-level lapse rates. Even so, rain bands will continue to wrap around the system throughout the day, and, given the strong low-level shear in place, any deeper, more persistent convective cores may be able to produce tornadoes. A relatively greater (but still quite low) threat may be able to develop across the Outer Banks vicinity if pockets of heating can occur within any cloud breaks. As the system gradually moves northwestward tonight, the loss of daytime heating suggests the tornado threat may become more confined closer to the center of the system over coastal northeast SC and coastal southern NC. ..Mosier/Lyons.. 08/07/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Wed Aug 07 2024 Valid 071700Z - 081200Z The previous forecast is largely on track. The Isolated Dry Thunder area was expanded westward slightly in Utah to reflect the latest thinking on thunderstorm coverage this afternoon. Otherwise, see the previous discussion for further details. ..Supinie.. 08/07/2024 .PREV DISCUSSION... /ISSUED 0119 AM CDT Wed Aug 07 2024/ ...Synopsis... ...Isolated Dry Thunderstorms... Isolated dry thunderstorms will be possible across portions of central/southern Utah, northwestern/central Colorado, and south-central Wyoming. A plume of mainly mid-level moisture, with precipitable water values around 0.50-0.75, will support high-based convection with little measurable rainfall, amid receptive fuels. Gusty and erratic outflow winds will be possible near thunderstorms. ...Wind/Dry... Enhanced mid-level westerly flow will remain over the Snake River Plain this afternoon. Sustained surface winds 15-20 mph will overlap with relative humidity reductions to 10-15 percent and receptive fuels. Elevated fire conditions may extend into northern Nevada, however this remains too localized to include with this outlook. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1857 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF COASTAL NORTH CAROLINA
Mesoscale Discussion 1857 NWS Storm Prediction Center Norman OK 1020 AM CDT Wed Aug 07 2024 Areas affected...portions of coastal North Carolina Concerning...Severe potential...Watch unlikely Valid 071520Z - 071745Z Probability of Watch Issuance...20 percent SUMMARY...A brief tornado cannot be ruled out through early afternoon. A WW issuance is not currently expected. DISCUSSION...Tropical Storm Debby continues to meander off of the coastline of the Carolinas as widespread rain/clouds from outer rain bands continue to overspread inland areas. Regional VADs (particularly LTX) depict sizable low-level hodographs and nearly 300 m2/s2 0-1 km SRH. However, despite mid to upper 70s F contributing to over 1000 J/kg SB/MLCAPE, boundary-layer lapse rates remains quite poor (both the 12Z MHX observed sounding and 15Z mesoanalysis show 5 C/km in the 0-3 km layer). Given the favorable low-level shear, a brief tornado cannot be completely ruled out, especially over far southern NC, where some breaks in the clouds were noted. Nonetheless, overall tornado coverage is expected to be sparse, and a WW issuance is not currently anticipated. ..Squitieri/Mosier.. 08/07/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MHX...RAH...ILM... LAT...LON 33617860 34107878 35117808 35857677 35957595 35587538 35117536 34557663 33767783 33617860 Read more

MD 1856 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF COASTAL NC INTO EXTREME NORTHEAST SC
Mesoscale Discussion 1856 NWS Storm Prediction Center Norman OK 0756 AM CDT Wed Aug 07 2024 Areas affected...Parts of coastal NC into extreme northeast SC Concerning...Severe potential...Watch unlikely Valid 071256Z - 071500Z Probability of Watch Issuance...20 percent SUMMARY...Some threat for a brief tornado or two may develop this morning. DISCUSSION...Multiple bands of convection to the northeast of Tropical Storm Debby are approaching coastal NC this morning, with occasional weak rotation noted offshore. Widespread cloudiness will inhibit diurnal heating inland today, but tropical moisture will continue to support MLCAPE of 1000-1500 J/kg near the coast, where temperatures can remain in the upper 70s to near 80 F (as noted on the 12Z MHX sounding). Low-level shear remains somewhat favorable for transient rotating cells, with 0-1 km SRH generally in the 100-200 m2/s2 range for observed storm motions this morning. As Debby gradually moves east-northeastward, slightly stronger low-level flow may overspread parts of coastal NC through the day, maintaining a low but persistent threat for a brief tornado, should any stronger cells develop and be sustained within banded convection over the northeast quadrant of Debby. ..Dean/Edwards.. 08/07/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MHX...RAH...ILM... LAT...LON 34317873 35117800 35667686 35557617 35047591 34567628 34087713 33727759 33487808 33307883 33467910 33947899 34317873 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0747 AM CDT Wed Aug 07 2024 Valid 071300Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL GREAT PLAINS AND COASTAL CAROLINAS... ...SUMMARY... Marginal severe-weather potential is apparent over parts of the central Great Plains and coastal Carolinas. ...Synopsis... The persistent western CONUS anticyclone will contract through the period and shift westward across the southern Great Basin, in response to both infusions of positive vorticity in its eastern semicircle, and more strongly, amplification/progression of a northern-stream synoptic trough over western/central Canada. That trough -- evident in moisture-channel imagery from a low over north-central MB west-southwestward across the Canadian Rockies -- will move southward through the period. By 12Z tomorrow, the 500-mb low should cross the remainder of central/southern MB to near the eastern ND/MB border. Associated height falls and cyclonic flow aloft will spread southward over the northern Plains today, to the central Plains late tonight. Downstream, the northern-stream flow will flatten to a more-zonal configuration through the period, across the Upper Great Lakes, the St. Lawrence Valley and northern New England. This temporarily maintains a dearth of steering flow near T.S. Debby, with weak poleward/inland motion forecast by NHC through 12Z tomorrow. See latest NHC advisories for track/intensity forecasts for Debby, as well as tropical watches/warnings. At the surface, 11Z analysis showed a wavy, quasistationary to slowly moving cold front from southern New England coastal waters westward over northeastern PA, then southwestward through a low near HTS, becoming a cold front over central KY to northeastern OK, through a low near LTS, then quasistationary again northwestward to a weak low over southeastern CO. The boundary should continue southward across parts of KY, TN, northern MS and AR, amidst broader northerlies extending westward from the circulation of T.S. Debby. A separate cold front -- related to the northern-stream perturbation over Canada -- was drawn from southeastern MB to near a BIS-RAP-RWL line. By 00Z, this front should extend from western parts of northwestern ON southwestward over northern MN, eastern SD, central NE, and northeastern CO. By 12Z tomorrow, the front should reach western parts of Lake Superior and WI, then southwestward over western IA, southeastern NE, southwestern KS, and northeastern NM. ...Central Great Plains... Widely scattered to scattered thunderstorms are forecast to form this afternoon and evening -- mainly on the cold front over NE and southeastern SD, and over higher elevations of southeastern WY and north-central/northeastern CO behind the front. Activity will pose a threat for isolated large hail and severe gusts before weakening overnight. Once an area of clouds and precip now over southern SD and northern NE exits the area, afternoon destabilization should reduce EML-related CINH ahead of the front through the afternoon, with frontal lift expected to be strong enough to break the cap in a few spots by late afternoon. Surface dewpoints in the upper 50s to low 60s F (locally higher) will contribute to a prefrontal plume of 1000-1500 J/kg MLCAPE that will narrow with northeastward extent into lower antecedent theta-e. The southern fringe of falls and a tightening gradient of heights aloft will extend across parts of this area from late afternoon onward as well, contributing to favorable deep shear for some storm organization and isolated supercell potential -- with effective-shear magnitudes generally 35-45 kt. Stronger veering with height -- but somewhat weaker mid/upper flow -- will characterize the post-frontal upslope regime, with elongated, nearly straight hodographs and similar bulk-shear values. Well-mixed subcloud layers will support gust potential, which may become concentrated on the mesobeta scale where any upscale clustering and cold-pool development can occur (most probable with activity initiated in the higher elevations). ...T.S. Debby -- Coastal Carolinas... As Debby gradually turns and moves northward to northwestward, only a slow corresponding shift of the tornado potential will occur. Inland destabilization is expected to be minimal, owing to extensive cloud cover and areas of precip north of center, and acting as a northern/northwestern limiter to the threat. Meanwhile the skeletal to almost nonexistent core convective structure and weaker shear will minimize potential closer to center. This leaves a segment of eastern NC near the sounds and Outer Banks today and tonight, as well as perhaps a small part of the adjoining SC coastal areas today, with potential for isolated, mainly short-lived supercells in the middle/outer bands. While hodographs are not forecast to be especially large, compared to many TC-tornado events, 150-250 J/kg effective SRH for northwestward-moving cells has been present in VWP hodographs and 6-hourly RAOBs, and should continue. This will overlap favorable buoyancy within roughly 75-100 nm inland of the beaches in NC. If a relatively concentrated area of sustained, multiple supercell development or potential appears for a particular band, a smaller area of greater probabilities may be added in a subsequent outlook. ..Edwards/Dean.. 08/07/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0747 AM CDT Wed Aug 07 2024 Valid 071300Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL GREAT PLAINS AND COASTAL CAROLINAS... ...SUMMARY... Marginal severe-weather potential is apparent over parts of the central Great Plains and coastal Carolinas. ...Synopsis... The persistent western CONUS anticyclone will contract through the period and shift westward across the southern Great Basin, in response to both infusions of positive vorticity in its eastern semicircle, and more strongly, amplification/progression of a northern-stream synoptic trough over western/central Canada. That trough -- evident in moisture-channel imagery from a low over north-central MB west-southwestward across the Canadian Rockies -- will move southward through the period. By 12Z tomorrow, the 500-mb low should cross the remainder of central/southern MB to near the eastern ND/MB border. Associated height falls and cyclonic flow aloft will spread southward over the northern Plains today, to the central Plains late tonight. Downstream, the northern-stream flow will flatten to a more-zonal configuration through the period, across the Upper Great Lakes, the St. Lawrence Valley and northern New England. This temporarily maintains a dearth of steering flow near T.S. Debby, with weak poleward/inland motion forecast by NHC through 12Z tomorrow. See latest NHC advisories for track/intensity forecasts for Debby, as well as tropical watches/warnings. At the surface, 11Z analysis showed a wavy, quasistationary to slowly moving cold front from southern New England coastal waters westward over northeastern PA, then southwestward through a low near HTS, becoming a cold front over central KY to northeastern OK, through a low near LTS, then quasistationary again northwestward to a weak low over southeastern CO. The boundary should continue southward across parts of KY, TN, northern MS and AR, amidst broader northerlies extending westward from the circulation of T.S. Debby. A separate cold front -- related to the northern-stream perturbation over Canada -- was drawn from southeastern MB to near a BIS-RAP-RWL line. By 00Z, this front should extend from western parts of northwestern ON southwestward over northern MN, eastern SD, central NE, and northeastern CO. By 12Z tomorrow, the front should reach western parts of Lake Superior and WI, then southwestward over western IA, southeastern NE, southwestern KS, and northeastern NM. ...Central Great Plains... Widely scattered to scattered thunderstorms are forecast to form this afternoon and evening -- mainly on the cold front over NE and southeastern SD, and over higher elevations of southeastern WY and north-central/northeastern CO behind the front. Activity will pose a threat for isolated large hail and severe gusts before weakening overnight. Once an area of clouds and precip now over southern SD and northern NE exits the area, afternoon destabilization should reduce EML-related CINH ahead of the front through the afternoon, with frontal lift expected to be strong enough to break the cap in a few spots by late afternoon. Surface dewpoints in the upper 50s to low 60s F (locally higher) will contribute to a prefrontal plume of 1000-1500 J/kg MLCAPE that will narrow with northeastward extent into lower antecedent theta-e. The southern fringe of falls and a tightening gradient of heights aloft will extend across parts of this area from late afternoon onward as well, contributing to favorable deep shear for some storm organization and isolated supercell potential -- with effective-shear magnitudes generally 35-45 kt. Stronger veering with height -- but somewhat weaker mid/upper flow -- will characterize the post-frontal upslope regime, with elongated, nearly straight hodographs and similar bulk-shear values. Well-mixed subcloud layers will support gust potential, which may become concentrated on the mesobeta scale where any upscale clustering and cold-pool development can occur (most probable with activity initiated in the higher elevations). ...T.S. Debby -- Coastal Carolinas... As Debby gradually turns and moves northward to northwestward, only a slow corresponding shift of the tornado potential will occur. Inland destabilization is expected to be minimal, owing to extensive cloud cover and areas of precip north of center, and acting as a northern/northwestern limiter to the threat. Meanwhile the skeletal to almost nonexistent core convective structure and weaker shear will minimize potential closer to center. This leaves a segment of eastern NC near the sounds and Outer Banks today and tonight, as well as perhaps a small part of the adjoining SC coastal areas today, with potential for isolated, mainly short-lived supercells in the middle/outer bands. While hodographs are not forecast to be especially large, compared to many TC-tornado events, 150-250 J/kg effective SRH for northwestward-moving cells has been present in VWP hodographs and 6-hourly RAOBs, and should continue. This will overlap favorable buoyancy within roughly 75-100 nm inland of the beaches in NC. If a relatively concentrated area of sustained, multiple supercell development or potential appears for a particular band, a smaller area of greater probabilities may be added in a subsequent outlook. ..Edwards/Dean.. 08/07/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Wed Aug 07 2024 Valid 101200Z - 151200Z ...DISCUSSION... Medium-range guidance indicates that the initially prominent higher-latitude mid-level ridging emerging from the Canadian Northwest Territories will gradually become suppressed through this period. Although there is notable spread concerning the downstream acceleration of the initially significant mid-level low to its southeast, it appears that larger-scale mid-level troughing will slowly shift eastward in positively tilted fashion, through the St. Lawrence Valley and lower Great Lakes region by late this coming weekend, through the Northeast and Canadian Maritimes by the middle of next week. In advance of the troughing, Debby's remnant surface low may interact with a surface cold front advancing to the east of the lower Great Lakes/upper Ohio Valley, before perhaps merging into the primary surface cyclone across southern Quebec by Saturday. Models have varied concerning these developments, but tropical pre-frontal moistening in the presence of intensifying deep-layer southerly wind fields might be accompanied by an evolving low-topped convective band with potential to produce damaging wind gusts near/east of the Hudson/Champlain Valleys through New England. Due to lingering uncertainties severe probabilities are begin maintained at less than 15 percent, but this could change in later outlooks for Saturday. Otherwise, the potential for severe weather elsewhere across the U.S. late this coming weekend into the middle of next week appears likely to be remain limited by the lack of stronger boundary-layer destabilization. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Wed Aug 07 2024 Valid 101200Z - 151200Z ...DISCUSSION... Medium-range guidance indicates that the initially prominent higher-latitude mid-level ridging emerging from the Canadian Northwest Territories will gradually become suppressed through this period. Although there is notable spread concerning the downstream acceleration of the initially significant mid-level low to its southeast, it appears that larger-scale mid-level troughing will slowly shift eastward in positively tilted fashion, through the St. Lawrence Valley and lower Great Lakes region by late this coming weekend, through the Northeast and Canadian Maritimes by the middle of next week. In advance of the troughing, Debby's remnant surface low may interact with a surface cold front advancing to the east of the lower Great Lakes/upper Ohio Valley, before perhaps merging into the primary surface cyclone across southern Quebec by Saturday. Models have varied concerning these developments, but tropical pre-frontal moistening in the presence of intensifying deep-layer southerly wind fields might be accompanied by an evolving low-topped convective band with potential to produce damaging wind gusts near/east of the Hudson/Champlain Valleys through New England. Due to lingering uncertainties severe probabilities are begin maintained at less than 15 percent, but this could change in later outlooks for Saturday. Otherwise, the potential for severe weather elsewhere across the U.S. late this coming weekend into the middle of next week appears likely to be remain limited by the lack of stronger boundary-layer destabilization. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0225 AM CDT Wed Aug 07 2024 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FRIDAY ACROSS PARTS OF NORTHEASTERN VIRGINIA...THE DISTRICT OF COLUMBIA...CENTRAL MARYLAND AND THE EASTERN SHORE OF MARYLAND...DELAWARE...SOUTHEASTERN PENNSYLVANIA...MUCH OF NEW JERSEY...ADJACENT SOUTHEASTERN NEW YORK AND WESTERN LONG ISLAND... ...SUMMARY... There may be at least some continuing risk for tornadoes in advance of the remnant low of Debby, spreading across the northern Mid Atlantic region on Friday. ...Synopsis... Models indicate that an initially prominent higher-latitude ridge will generally be maintained through this period, with its mid-level height center perhaps slowly shifting east of the Canadian Northwest Territories. Some eastward redevelopment of a significant low evolving to its southeast may also commence, as a couple of embedded perturbations pivot around its circulation center near the upper Great Lakes region. This may be accompanied by modest secondary surface cyclogenesis, along an occluding surface front across the lower Great Lakes into upper St. Lawrence Valley vicinity, with a trailing cold front advancing through the remainder of the Ohio Valley, into and across the Appalachians. Through the day, Debby's remnant circulation, forecast to weaken to a depression by 12Z Friday and a remnant low by early Friday evening, appears likely to continue a gradual north-northeastward acceleration ahead of the front, to the lee of the Blue Ridge, before continuing toward the Catskill/lower Hudson Valley vicinity Friday night. ...Northern Mid Atlantic... Despite the weakening trends to Debby, models suggest that the evolution of sizable clockwise-curved low-level hodographs and appreciable boundary-layer buoyancy may be maintained into at least Friday afternoon, focused in a sector to the northeast of the accelerating surface low. It appears that this may be in the process of overspreading the Chesapeake/Delmarva vicinity as daytime heating contributes to boundary-layer destabilization, before spreading northward through the northern Mid Atlantic in advance of the more inhibiting mid-level warm core. Within this environment, the evolution of a few supercell structures posing a risk for tornadoes appears possible, before this threat wanes with the loss of daytime heating Friday evening. ..Kerr.. 08/07/2024 Read more

MD 1855 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHEAST NC INTO EXTREME NORTHEAST SC
Mesoscale Discussion 1855 NWS Storm Prediction Center Norman OK 0155 AM CDT Wed Aug 07 2024 Areas affected...Southeast NC into extreme northeast SC Concerning...Severe potential...Watch unlikely Valid 070655Z - 071000Z Probability of Watch Issuance...20 percent SUMMARY...A brief tornado or two will be possible overnight. DISCUSSION...A band of convection along the east/northeast periphery of Tropical Storm Debby's circulation has become somewhat more well-defined early this morning. A theta-e/instability gradient persists near the coast, with a narrow inland zone of MLCAPE near 1000 J/kg noted (per recent objective mesoanalyses and a modified 06Z sounding from KMHX) where temperatures remain near 80 F. The 06Z MHX sounding and recent VWPs from KMHX/KLTX depict 0-1 km SRH of around 150-200 m2/s2 for observed cell motions, which is sufficient to support at least transient low-level rotation with the strongest cells. While ongoing convection has generally struggled to become organized, a brief tornado or two cannot be ruled out overnight as stronger embedded cells within the primary convective band move inland and cross the near-coastal baroclinic zone. ..Dean/Edwards.. 08/07/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MHX...ILM... LAT...LON 34147884 34387852 35037745 35037690 34857667 34427693 33847770 33627823 33527882 33797896 34147884 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Wed Aug 07 2024 Valid 081200Z - 091200Z ...Synopsis... A trough moving across the northern Rockies into the northern Plains will suppress the western US ridge on Thursday. Flow aloft will shift to become more northwesterly, with monsoonal moisture shifting southward. Isolated dry thunderstorm chances will be possible along the fringes of the deeper monsoonal moisture across southern/central Utah into western Colorado and western Wyoming. In this region, precipitable water values around 0.50-0.75 inch and mainly mid-level moisture will result in high-based convection, with potential for new ignitions amid receptive fuels, and little precipitation. Gusty and erratic winds will be possible near thunderstorms. ..Thornton.. 08/07/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more