Storm Prediction Center

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Jul 20 2026 Valid 202000Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE UPPER MIDWEST... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest and Great Lakes vicinity, especially late this afternoon into late evening. A few strong-intense tornadoes, swaths of damaging winds, and isolated very large hail will all be possible. Isolated damaging gusts may also occur over parts of North Carolina this afternoon. ...20z Update... The previous forecast largely remains on track with only minor adjustments made. Recent GOES imagery and surface observations show gradually building cumulus across eastern MN into northwest WI along a diffuse surface cold front. Latest high-res guidance suggests this will be the primary initiation zone over the next few hours, which increases confidence in the downstream severe threat and implies the severe threat is diminishing for areas further west. Risk probabilities were trimmed across northeast MN to reflect this trend. Elevated convection migrating across southeast MN/WI are indicative of steeper mid-level lapse rates (observed in upstream 18 UTC soundings) spreading east in the wake of this morning's weak MCS. This, coupled with steady warming/moistening of the low-level air mass and 50-60 knot mid-level flow observed by the KMPX and KDVN VWPs, lends confidence in the ongoing forecast for much of the region. See the previous discussion (below) and MCD #1674 for additional forecast details. ...North Carolina... Ongoing thunderstorms have exhibited pulse-like behavior over the past few hours across NC and adjacent areas. While much of this activity has been sub-severe, low-level thermodynamic conditions will remain favorable through early evening for strong to severe downburst winds. Given the ongoing coverage of convection across north-central NC, 15% risk probabilities were maintained. Elsewhere, more isolated strong/severe winds appear possible across northeast ND/northwest MN as a pocket of colder mid-level temperatures coincident with 30-40 knot low-level winds overspreads the region in tandem with the primary mid/upper-level trough. Similarly, very sporadic severe gusts associated with downbursts within a deeply-mixed environment are possible across central/southern AZ, as well as northern FL/far southern GA where local velocity data shows embedded swaths of strong winds associated with the outer convective bands of Tropical Depression 2. However, all of these regions, the kinematic/thermodynamic environments appear fairly marginal and/or convective signals in recent ensemble guidance are too weak to warrant severe wind highlights. ..Moore.. 07/20/2026 .PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Jul 20 2026/ ...Upper Midwest through tonight... A midlevel shortwave trough is cresting the ridge and will turn southeastward today while moving over the upper MS Valley, as an associated cold front likewise moves southeastward into Upper MI, WI and IA. Earlier storms in Upper MI have weakened, while a cluster is ongoing in eastern IA. Destabilization will occur in the wake of the eastern IA storms as a reservoir of low-mid 70s boundary-layer dewpoints spreads northeastward from IA/southern MN into WI and western Upper MI. The low-level moistening will occur beneath a plume of midlevel lapse rates greater than 8 C/km and in tandem with surface heating in cloud breaks, all of which will drive MLCAPE in excess of 3000 J/kg. As is typical with lingering morning convection, there is some uncertainty regarding the specific locations of afternoon storm development in its wake. Wind profiles will favor supercells as the initial storm mode this afternoon along and just ahead of the cold front, given very long hodographs oriented largely orthogonal to the front. Low-level shear/hodograph curvature will also be substantial, which combined with the moist boundary layer, steep lapse rates and large buoyancy will support the potential for a few strong-intense tornadoes. Very large hail will be possible with the more discrete supercells, while significant severe outflow gusts will be possible with any clustering of storms later this afternoon/evening. Initial supercells will likely evolve into a cluster or two by early tonight while spreading southeastward across eastern IA, northern IL, northwest IN and Lower MI with a continued threat for occasional wind damage and isolated large hail. ...Central NC area this afternoon/evening... Thunderstorm development is expected again this afternoon along a stalled front/differential heating zone across NC, to the west of the more persistent cloud cover in far eastern NC. NC remains near the south edge of the midlevel westerlies, with mid 70s boundary-layer dewpoints coincident with temperatures at or above 90 F contributing to MLCAPE in excess of 2000 J/kg. A few damaging downbursts will be possible with precipitation-loaded downdrafts in an environment with steepening low-level lapse rates. ...FL Big Bend today... Tropical Depression #2 is forecast to drift slowly westward across the northeast Gulf through tomorrow and become a tropical storm. Though deep-layer wind profiles are not particularly favorable in the northeast quadrant of the cyclone, where winds aloft are from the northeast, there is just enough low-level shear to support weakly rotating storms in the outer convective bands. An isolated tornado/waterspout or two may occur today in coastal areas of the FL Big Bend. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Jul 20 2026 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF NORTH CAROLINA INTO SOUTHEAST VIRGINIA... ...SUMMARY... Isolated strong to severe thunderstorms will pose a risk for damaging wind gusts across parts of southeast Virginia and North Carolina. ...Discussion... Upper-level troughing will remain in place across the eastern US on D3/Wednesday, with several shortwave impulses rotating through. A cold front will be located roughly from the Mid-Atlantic south into the Carolinas and western Tennessee. Moisture will be largely scoured out behind this front, with the more favorable plume of moist air remaining east of the Appalachians and Blue Ridge Mountains across southern New England into the Mid-Atlantic/Carolinas. Daytime heating will be maximized from the Mid-Atlantic southward to the Carolinas, where moderate instability will be realized by the afternoon. Instability will be more marginal with north extent into New England, though strong deep layer shear may still support a few organized storms. Widely scattered thunderstorm development is expected near and ahead of the cold front by the afternoon, with the main hazard being damaging wind, with the greatest risk across parts of VA/NC and vicinity. Outer bands of Tropical Depression Two will bring thunderstorms potential inland across the Gulf States by D3/Wednesday. The tornado threat appears to be too marginal for an outlook area at this time. See advisories from the National Hurricane Center for more information on this potential (nhc.noaa.gov). ..Thornton.. 07/20/2026 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 PM CDT Mon Jul 20 2026 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF NORTH CAROLINA INTO SOUTHEAST VIRGINIA... ...SUMMARY... Isolated strong to severe thunderstorms will pose a risk for damaging wind gusts across parts of southeast Virginia and North Carolina. ...Discussion... Upper-level troughing will remain in place across the eastern US on D3/Wednesday, with several shortwave impulses rotating through. A cold front will be located roughly from the Mid-Atlantic south into the Carolinas and western Tennessee. Moisture will be largely scoured out behind this front, with the more favorable plume of moist air remaining east of the Appalachians and Blue Ridge Mountains across southern New England into the Mid-Atlantic/Carolinas. Daytime heating will be maximized from the Mid-Atlantic southward to the Carolinas, where moderate instability will be realized by the afternoon. Instability will be more marginal with north extent into New England, though strong deep layer shear may still support a few organized storms. Widely scattered thunderstorm development is expected near and ahead of the cold front by the afternoon, with the main hazard being damaging wind, with the greatest risk across parts of VA/NC and vicinity. Outer bands of Tropical Depression Two will bring thunderstorms potential inland across the Gulf States by D3/Wednesday. The tornado threat appears to be too marginal for an outlook area at this time. See advisories from the National Hurricane Center for more information on this potential (nhc.noaa.gov). ..Thornton.. 07/20/2026 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0213 PM CDT Mon Jul 20 2026 Valid 211200Z - 221200Z Minor modifications were made to the IsoDryT area based on the latest observations and high-resolution forecast guidance. Southern/central Oregon remain the mostly likely area for mixed wet/dry thunderstorm development. Cloud cover, smoke, and warmer temperatures aloft will help limit thunderstorm development/coverage across the IsoDryT area, but isolated thunderstorms remain possible if not likely. Additionally, if the upper low off the coast shifts farther east in the next 24-36 hours, this will help increase thunderstorm probabilities and coverage, including overnight. Locally elevated conditions are likely in portions of South Carolina as south-southwest sustained winds of 10-15 mph overlap minimum RH of 30-40%. ERCs generally range from the 80th-95th percentile across this area. ..Nauslar.. 07/20/2026 .PREV DISCUSSION... /ISSUED 0149 AM CDT Mon Jul 20 2026/ ...Synopsis... Along the northwestern periphery of a large-scale ridge encompassing much of the central and western CONUS, ample midlevel moisture will be in place atop a warm and dry air mass across parts of northern CA into OR. This will yield inverted-V profiles with weak (albeit sufficient) buoyancy for isolated high-based thunderstorms across the area during the afternoon and evening hours. Given relatively weak large-scale forcing for ascent, the greatest confidence in thunderstorm development is over the Cascades in southern/central OR. While 0.8 to 1.2 inch PW may promote a mix of wet/dry storms, relatively fast storm motions and the dry boundary layer should limit rainfall. As a result, isolated lightning-induced ignitions will be possible. Elsewhere across the CONUS, minimal fire-weather concerns are expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0213 PM CDT Mon Jul 20 2026 Valid 211200Z - 221200Z Minor modifications were made to the IsoDryT area based on the latest observations and high-resolution forecast guidance. Southern/central Oregon remain the mostly likely area for mixed wet/dry thunderstorm development. Cloud cover, smoke, and warmer temperatures aloft will help limit thunderstorm development/coverage across the IsoDryT area, but isolated thunderstorms remain possible if not likely. Additionally, if the upper low off the coast shifts farther east in the next 24-36 hours, this will help increase thunderstorm probabilities and coverage, including overnight. Locally elevated conditions are likely in portions of South Carolina as south-southwest sustained winds of 10-15 mph overlap minimum RH of 30-40%. ERCs generally range from the 80th-95th percentile across this area. ..Nauslar.. 07/20/2026 .PREV DISCUSSION... /ISSUED 0149 AM CDT Mon Jul 20 2026/ ...Synopsis... Along the northwestern periphery of a large-scale ridge encompassing much of the central and western CONUS, ample midlevel moisture will be in place atop a warm and dry air mass across parts of northern CA into OR. This will yield inverted-V profiles with weak (albeit sufficient) buoyancy for isolated high-based thunderstorms across the area during the afternoon and evening hours. Given relatively weak large-scale forcing for ascent, the greatest confidence in thunderstorm development is over the Cascades in southern/central OR. While 0.8 to 1.2 inch PW may promote a mix of wet/dry storms, relatively fast storm motions and the dry boundary layer should limit rainfall. As a result, isolated lightning-induced ignitions will be possible. Elsewhere across the CONUS, minimal fire-weather concerns are expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Mon Jul 20 18:55:02 UTC 2026.

MD 1674 CONCERNING SEVERE POTENTIAL...TORNADO WATCH LIKELY FOR NORTHEAST IOWA INTO NORTHWEST/NORTH-CENTRAL WISCONSIN
Mesoscale Discussion 1674 NWS Storm Prediction Center Norman OK 0153 PM CDT Mon Jul 20 2026 Areas affected...Northeast Iowa into northwest/north-central Wisconsin Concerning...Severe potential...Tornado Watch likely Valid 201853Z - 202100Z Probability of Watch Issuance...95 percent SUMMARY...All severe hazards, including some significant, are possible as supercells develop by late afternoon. Timing and location of initiation are the main uncertainties. A tornado watch is likely. DISCUSSION...A very moist airmass is evident ahead of a cold front in the Upper Mississippi Valley. A capping inversion was present on the 12Z MPX observed sounding. Cumulus along the front have yet to become vertically developed as a result. Mid-level convection has been ongoing in southern Minnesota. This activity is now moving into modifying outflow from an earlier MCS in the La Crosse/Davenport vicinity. Lift from a shortwave trough in northern Minnesota will continue to overspread the area this afternoon. With time, continued heating and moistening ahead of the cold front and near the outflow front intersection should allow storms to develop, most likely by late afternoon. Given strong shear (50-60 kt effective) across the cold front, supercell structures will be favored. Steep mid-level lapse rates will support the threat for large to very-large hail. A tornado threat, some possibly strong, will also be present with supercells. Severe winds will also be possible. Wind gusts of 75+ mph are possible, particularly where activity grows upscale. The exact timing/location of storm initiation is not clear though a tornado watch is likely. ..Wendt/Thompson.. 07/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB...MKX...DLH...ARX...MPX... LAT...LON 43609277 44549244 46519079 46729022 46408897 45168894 43798985 43379033 43099126 43079238 43609277 MOST PROBABLE PEAK TORNADO INTENSITY...120-145 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN Read more

MD 1673 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF FAR SOUTHERN VIRGINIA INTO MUCH OF NORTH CAROLINA
Mesoscale Discussion 1673 NWS Storm Prediction Center Norman OK 1220 PM CDT Mon Jul 20 2026 Areas affected...portions of far southern Virginia into much of North Carolina Concerning...Severe potential...Watch unlikely Valid 201720Z - 201915Z Probability of Watch Issuance...20 percent SUMMARY...Strong to occasionally severe thunderstorms may produce isolated damaging wind gusts through this evening. DISCUSSION...Hot and humid conditions remain in place across much of North Carolina and portions of Virginia in the vicinity of a stationary surface front that extends roughly west-to-east across northern NC. As surface temperatures increase amid continued diurnal heating over the next couple of hours, scattered thunderstorm initiation is expected along the Blue Ridge, the surface front, and outflow/sea breeze boundaries near the coast. Similar to yesterday, an outflow-dominant storm mode is likely given that deep-layer flow remains fairly week. However, 20-25 kts of mid-level flow sampled by regional VWPs may aid in marginal storm organization across the region. In conjunction with steepening low-level lapse rates, a moderately to strongly unstable environment, and high PW, this will support a risk for water-loaded downbursts capable of occasionally damaging wind gusts. Locally greater potential may develop across portions of the NC Coastal Plain where the best overlap of thermodynamic parameters is expected. Watch issuance appears unlikely at this time, but a targeted Severe Thunderstorm Watch could be considered should a corridor of greater severe potential become apparent. ..Chalmers/Thompson.. 07/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...MHX...RAH...ILM...RNK...CAE...GSP...MRX... LAT...LON 36487682 36437642 36357581 36137556 35687532 35177544 34757615 34487669 34407756 34417812 34637971 34908108 35118156 35398199 35848218 36378216 36788188 37068145 37188106 37258065 37258040 37218011 37087976 36837909 36627844 36567781 36527732 36487682 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Jul 20 2026 Valid 211200Z - 221200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE UPPER OHIO VALLEY INTO THE MID-ATLANTIC... ...SUMMARY... Numerous severe thunderstorms are expected across a broad region from the Ohio Valley into the Mid-Atlantic and Northeast on Tuesday. All severe hazards are possible, but swaths of damaging wind gusts should be the primary severe risk Tuesday afternoon into the nighttime hours. ...Synopsis... High amplitude ridging will build across the western US with continued progressive troughing across the east on Tuesday. Multiple short-wave impulses will rotate through the eastern US trough, with a belt of enhanced northwesterly flow traversing the Midwest into the Ohio Valley. At the surface, a cold front will shift south and east through the period, with a surface low across southern Ontario/Quebec. A pre-frontal surface trough will also be in place across western/central NY into the Mid-Atlantic vicinity. Widely scattered thunderstorm activity is expected through the period. ...Mid-Atlantic and Northeast... Thunderstorm activity is expected to increase along the pre-frontal trough from western/central New York into the Northeast/Mid-Atlantic late Tuesday morning into the afternoon. Though there may be potential for early morning cloud cover, it does appear that sufficient heating/moistening will occur for at least moderate instability to develop across the region through the afternoon. Mid-level flow will increase through the day along with forcing for ascent. It appears widely scattered thunderstorm activity with several clusters/embedded supercells will be ongoing by the afternoon. Highest confidence in transient embedded supercell modes would be closer to the surface low and near the front across western NY into eastern PA. Here, there may be potential for both damaging wind, large hail, and perhaps a couple of tornadoes. Guidance suggests the best signal for damaging wind will be across the Mid-Atlantic, where several damaging clusters could occur. As such, the Enhanced was expanded eastward into portions of the Mid-Atlantic. ...Ohio Valley... Evolution of overnight convection will play a large role in development/maintenance of thunderstorm activity across the Ohio Valley Tuesday. It appears that remnant convection will be ongoing at the start of the period near/just ahead of the surface front across northern Kentucky/southern Indiana/Ohio. This will likely re-intensify and continue to expand south and east during the morning as daytime heating begins. Strong daytime heating and moist profiles should support moderate to strong instability developing though the afternoon. Storm mode appears to be generally linear, with the greatest threat being for damaging wind given more linear forcing/initially boundary parallel shear along residual southward moving outflow. As such, the primary hazard will be damaging wind. Additional thunderstorm development is likely along and ahead of the front through the afternoon with increasing forcing for ascent with approaching shortwaves. Strong deep layer shear may become more boundary perpendicular supporting a supercell or two as the front sags south, with potential for large hail and perhaps a tornado. Confidence in this scenario is on the lower end and the primary hazard is expected to be a secondary wave of damaging wind potential. Should storms be able to cluster and establish a more organized cold pool, potential for some corridor of significant wind may be possible. Overall, no significant wind areas were included given low confidence in exact morning storm evolution and concerns over generally poor lapse rates. ..Thornton.. 07/20/2026 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Jul 20 2026 Valid 211200Z - 221200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE UPPER OHIO VALLEY INTO THE MID-ATLANTIC... ...SUMMARY... Numerous severe thunderstorms are expected across a broad region from the Ohio Valley into the Mid-Atlantic and Northeast on Tuesday. All severe hazards are possible, but swaths of damaging wind gusts should be the primary severe risk Tuesday afternoon into the nighttime hours. ...Synopsis... High amplitude ridging will build across the western US with continued progressive troughing across the east on Tuesday. Multiple short-wave impulses will rotate through the eastern US trough, with a belt of enhanced northwesterly flow traversing the Midwest into the Ohio Valley. At the surface, a cold front will shift south and east through the period, with a surface low across southern Ontario/Quebec. A pre-frontal surface trough will also be in place across western/central NY into the Mid-Atlantic vicinity. Widely scattered thunderstorm activity is expected through the period. ...Mid-Atlantic and Northeast... Thunderstorm activity is expected to increase along the pre-frontal trough from western/central New York into the Northeast/Mid-Atlantic late Tuesday morning into the afternoon. Though there may be potential for early morning cloud cover, it does appear that sufficient heating/moistening will occur for at least moderate instability to develop across the region through the afternoon. Mid-level flow will increase through the day along with forcing for ascent. It appears widely scattered thunderstorm activity with several clusters/embedded supercells will be ongoing by the afternoon. Highest confidence in transient embedded supercell modes would be closer to the surface low and near the front across western NY into eastern PA. Here, there may be potential for both damaging wind, large hail, and perhaps a couple of tornadoes. Guidance suggests the best signal for damaging wind will be across the Mid-Atlantic, where several damaging clusters could occur. As such, the Enhanced was expanded eastward into portions of the Mid-Atlantic. ...Ohio Valley... Evolution of overnight convection will play a large role in development/maintenance of thunderstorm activity across the Ohio Valley Tuesday. It appears that remnant convection will be ongoing at the start of the period near/just ahead of the surface front across northern Kentucky/southern Indiana/Ohio. This will likely re-intensify and continue to expand south and east during the morning as daytime heating begins. Strong daytime heating and moist profiles should support moderate to strong instability developing though the afternoon. Storm mode appears to be generally linear, with the greatest threat being for damaging wind given more linear forcing/initially boundary parallel shear along residual southward moving outflow. As such, the primary hazard will be damaging wind. Additional thunderstorm development is likely along and ahead of the front through the afternoon with increasing forcing for ascent with approaching shortwaves. Strong deep layer shear may become more boundary perpendicular supporting a supercell or two as the front sags south, with potential for large hail and perhaps a tornado. Confidence in this scenario is on the lower end and the primary hazard is expected to be a secondary wave of damaging wind potential. Should storms be able to cluster and establish a more organized cold pool, potential for some corridor of significant wind may be possible. Overall, no significant wind areas were included given low confidence in exact morning storm evolution and concerns over generally poor lapse rates. ..Thornton.. 07/20/2026 Read more

MD 1672 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHEAST IOWAS INTO WEST-CENTRAL ILLINOIS AND FAR NORTHEAST MISSOURI
Mesoscale Discussion 1672 NWS Storm Prediction Center Norman OK 1136 AM CDT Mon Jul 20 2026 Areas affected...Southeast Iowas into west-central Illinois and far northeast Missouri Concerning...Severe potential...Watch possible Valid 201636Z - 201830Z Probability of Watch Issuance...40 percent SUMMARY...Some increase in strong to severe wind gusts is possible with a compact MCS in east-central Iowa. A watch is possible depending on convective trends over the next 1-2 hours. DISCUSSION...Modest destabilization continues ahead of a compact MCS in east-central Iowa. Temperatures to the south/southwest of this cluster have risen into the low to upper 80s F. The motion of the system is generally southeastward which would tend to move it into less unstable air in Illinois. Activity on the western flank of the MCS and its trailing outflow will likely be the strongest given the stronger heating and steeper mid-level lapse rates. Some potential for strong to severe wind gusts will be present. Recent measured wind gusts at Cedar Rapids and Iowa City were 35 and 36 kt, respectively, with a mesonet site also measuring 55 mph in Jones County. A watch is possible depending on convective trends over the next hour or two. ..Wendt/Thompson.. 07/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ILX...LSX...DVN...DMX... LAT...LON 40259197 41299253 41789250 41919243 41859208 41799169 41739122 41809050 41319033 40619024 40219034 40049106 40059137 40259197 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Jul 20 2026 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FROM EASTERN IOWA AND NORTHWESTERN ILLINOIS ACROSS WISCONSIN INTO WESTERN UPPER MICHIGAN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS CENTRAL NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest and Great Lakes vicinity, especially late this afternoon into late evening. A few strong-intense tornadoes, swaths of damaging winds, and isolated very large hail will all be possible. Isolated damaging gusts may also occur over parts North Carolina this afternoon. ...Upper Midwest through tonight... A midlevel shortwave trough is cresting the ridge and will turn southeastward today while moving over the upper MS Valley, as an associated cold front likewise moves southeastward into Upper MI, WI and IA. Earlier storms in Upper MI have weakened, while a cluster is ongoing in eastern IA. Destabilization will occur in the wake of the eastern IA storms as a reservoir of low-mid 70s boundary-layer dewpoints spreads northeastward from IA/southern MN into WI and western Upper MI. The low-level moistening will occur beneath a plume of midlevel lapse rates greater than 8 C/km and in tandem with surface heating in cloud breaks, all of which will drive MLCAPE in excess of 3000 J/kg. As is typical with lingering morning convection, there is some uncertainty regarding the specific locations of afternoon storm development in its wake. Wind profiles will favor supercells as the initial storm mode this afternoon along and just ahead of the cold front, given very long hodographs oriented largely orthogonal to the front. Low-level shear/hodograph curvature will also be substantial, which combined with the moist boundary layer, steep lapse rates and large buoyancy will support the potential for a few strong-intense tornadoes. Very large hail will be possible with the more discrete supercells, while significant severe outflow gusts will be possible with any clustering of storms later this afternoon/evening. Initial supercells will likely evolve into a cluster or two by early tonight while spreading southeastward across eastern IA, northern IL, northwest IN and Lower MI with a continued threat for occasional wind damage and isolated large hail. ...Central NC area this afternoon/evening... Thunderstorm development is expected again this afternoon along a stalled front/differential heating zone across NC, to the west of the more persistent cloud cover in far eastern NC. NC remains near the south edge of the midlevel westerlies, with mid 70s boundary-layer dewpoints coincident with temperatures at or above 90 F contributing to MLCAPE in excess of 2000 J/kg. A few damaging downbursts will be possible with precipitation-loaded downdrafts in an environment with steepening low-level lapse rates. ...FL Big Bend today... Tropical Depression #2 is forecast to drift slowly westward across the northeast Gulf through tomorrow and become a tropical storm. Though deep-layer wind profiles are not particularly favorable in the northeast quadrant of the cyclone, where winds aloft are from the northeast, there is just enough low-level shear to support weakly rotating storms in the outer convective bands. An isolated tornado/waterspout or two may occur today in coastal areas of the FL Big Bend. ..Thompson/Chalmers.. 07/20/2026 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Jul 20 2026 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FROM EASTERN IOWA AND NORTHWESTERN ILLINOIS ACROSS WISCONSIN INTO WESTERN UPPER MICHIGAN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS CENTRAL NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest and Great Lakes vicinity, especially late this afternoon into late evening. A few strong-intense tornadoes, swaths of damaging winds, and isolated very large hail will all be possible. Isolated damaging gusts may also occur over parts North Carolina this afternoon. ...Upper Midwest through tonight... A midlevel shortwave trough is cresting the ridge and will turn southeastward today while moving over the upper MS Valley, as an associated cold front likewise moves southeastward into Upper MI, WI and IA. Earlier storms in Upper MI have weakened, while a cluster is ongoing in eastern IA. Destabilization will occur in the wake of the eastern IA storms as a reservoir of low-mid 70s boundary-layer dewpoints spreads northeastward from IA/southern MN into WI and western Upper MI. The low-level moistening will occur beneath a plume of midlevel lapse rates greater than 8 C/km and in tandem with surface heating in cloud breaks, all of which will drive MLCAPE in excess of 3000 J/kg. As is typical with lingering morning convection, there is some uncertainty regarding the specific locations of afternoon storm development in its wake. Wind profiles will favor supercells as the initial storm mode this afternoon along and just ahead of the cold front, given very long hodographs oriented largely orthogonal to the front. Low-level shear/hodograph curvature will also be substantial, which combined with the moist boundary layer, steep lapse rates and large buoyancy will support the potential for a few strong-intense tornadoes. Very large hail will be possible with the more discrete supercells, while significant severe outflow gusts will be possible with any clustering of storms later this afternoon/evening. Initial supercells will likely evolve into a cluster or two by early tonight while spreading southeastward across eastern IA, northern IL, northwest IN and Lower MI with a continued threat for occasional wind damage and isolated large hail. ...Central NC area this afternoon/evening... Thunderstorm development is expected again this afternoon along a stalled front/differential heating zone across NC, to the west of the more persistent cloud cover in far eastern NC. NC remains near the south edge of the midlevel westerlies, with mid 70s boundary-layer dewpoints coincident with temperatures at or above 90 F contributing to MLCAPE in excess of 2000 J/kg. A few damaging downbursts will be possible with precipitation-loaded downdrafts in an environment with steepening low-level lapse rates. ...FL Big Bend today... Tropical Depression #2 is forecast to drift slowly westward across the northeast Gulf through tomorrow and become a tropical storm. Though deep-layer wind profiles are not particularly favorable in the northeast quadrant of the cyclone, where winds aloft are from the northeast, there is just enough low-level shear to support weakly rotating storms in the outer convective bands. An isolated tornado/waterspout or two may occur today in coastal areas of the FL Big Bend. ..Thompson/Chalmers.. 07/20/2026 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Jul 20 2026 Valid 201630Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FROM EASTERN IOWA AND NORTHWESTERN ILLINOIS ACROSS WISCONSIN INTO WESTERN UPPER MICHIGAN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON ACROSS CENTRAL NORTH CAROLINA... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest and Great Lakes vicinity, especially late this afternoon into late evening. A few strong-intense tornadoes, swaths of damaging winds, and isolated very large hail will all be possible. Isolated damaging gusts may also occur over parts North Carolina this afternoon. ...Upper Midwest through tonight... A midlevel shortwave trough is cresting the ridge and will turn southeastward today while moving over the upper MS Valley, as an associated cold front likewise moves southeastward into Upper MI, WI and IA. Earlier storms in Upper MI have weakened, while a cluster is ongoing in eastern IA. Destabilization will occur in the wake of the eastern IA storms as a reservoir of low-mid 70s boundary-layer dewpoints spreads northeastward from IA/southern MN into WI and western Upper MI. The low-level moistening will occur beneath a plume of midlevel lapse rates greater than 8 C/km and in tandem with surface heating in cloud breaks, all of which will drive MLCAPE in excess of 3000 J/kg. As is typical with lingering morning convection, there is some uncertainty regarding the specific locations of afternoon storm development in its wake. Wind profiles will favor supercells as the initial storm mode this afternoon along and just ahead of the cold front, given very long hodographs oriented largely orthogonal to the front. Low-level shear/hodograph curvature will also be substantial, which combined with the moist boundary layer, steep lapse rates and large buoyancy will support the potential for a few strong-intense tornadoes. Very large hail will be possible with the more discrete supercells, while significant severe outflow gusts will be possible with any clustering of storms later this afternoon/evening. Initial supercells will likely evolve into a cluster or two by early tonight while spreading southeastward across eastern IA, northern IL, northwest IN and Lower MI with a continued threat for occasional wind damage and isolated large hail. ...Central NC area this afternoon/evening... Thunderstorm development is expected again this afternoon along a stalled front/differential heating zone across NC, to the west of the more persistent cloud cover in far eastern NC. NC remains near the south edge of the midlevel westerlies, with mid 70s boundary-layer dewpoints coincident with temperatures at or above 90 F contributing to MLCAPE in excess of 2000 J/kg. A few damaging downbursts will be possible with precipitation-loaded downdrafts in an environment with steepening low-level lapse rates. ...FL Big Bend today... Tropical Depression #2 is forecast to drift slowly westward across the northeast Gulf through tomorrow and become a tropical storm. Though deep-layer wind profiles are not particularly favorable in the northeast quadrant of the cyclone, where winds aloft are from the northeast, there is just enough low-level shear to support weakly rotating storms in the outer convective bands. An isolated tornado/waterspout or two may occur today in coastal areas of the FL Big Bend. ..Thompson/Chalmers.. 07/20/2026 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1035 AM CDT Mon Jul 20 2026 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... High-based showers remain expected across portions of northern California and the Northwest today and tonight, with occasional embedded lightning possible. Locally elevated conditions are likely in portions of northern Minnesota as west-northwest sustained winds of 15-20 mph and minimum RH of 25-35% overlap behind a cold front. Additionally, post-frontal locally elevated conditions are likely in portions of the Dakotas into eastern Montana with north-northwest sustained winds of 10-20 mph amid minimum RH of 20-35%. ..Nauslar.. 07/20/2026 .PREV DISCUSSION... /ISSUED 0148 AM CDT Mon Jul 20 2026/ ...Synopsis... Along the northwestern periphery of an expansive upper ridge over the West, a low-amplitude midlevel disturbance and accompanying influx of midlevel moisture will overspread parts of the Northwest today. While this should support isolated high-based showers, weak buoyancy and warm EL temperatures should limit thunderstorm potential. With that said, an isolated storm or two cannot be entirely ruled out over the Cascades in OR. Elsewhere, a limited overlap of dry/windy conditions atop receptive fuels will reduce fire-weather concerns across the CONUS. ...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 1035 AM CDT Mon Jul 20 2026 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... High-based showers remain expected across portions of northern California and the Northwest today and tonight, with occasional embedded lightning possible. Locally elevated conditions are likely in portions of northern Minnesota as west-northwest sustained winds of 15-20 mph and minimum RH of 25-35% overlap behind a cold front. Additionally, post-frontal locally elevated conditions are likely in portions of the Dakotas into eastern Montana with north-northwest sustained winds of 10-20 mph amid minimum RH of 20-35%. ..Nauslar.. 07/20/2026 .PREV DISCUSSION... /ISSUED 0148 AM CDT Mon Jul 20 2026/ ...Synopsis... Along the northwestern periphery of an expansive upper ridge over the West, a low-amplitude midlevel disturbance and accompanying influx of midlevel moisture will overspread parts of the Northwest today. While this should support isolated high-based showers, weak buoyancy and warm EL temperatures should limit thunderstorm potential. With that said, an isolated storm or two cannot be entirely ruled out over the Cascades in OR. Elsewhere, a limited overlap of dry/windy conditions atop receptive fuels will reduce fire-weather concerns across the CONUS. ...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 1035 AM CDT Mon Jul 20 2026 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... High-based showers remain expected across portions of northern California and the Northwest today and tonight, with occasional embedded lightning possible. Locally elevated conditions are likely in portions of northern Minnesota as west-northwest sustained winds of 15-20 mph and minimum RH of 25-35% overlap behind a cold front. Additionally, post-frontal locally elevated conditions are likely in portions of the Dakotas into eastern Montana with north-northwest sustained winds of 10-20 mph amid minimum RH of 20-35%. ..Nauslar.. 07/20/2026 .PREV DISCUSSION... /ISSUED 0148 AM CDT Mon Jul 20 2026/ ...Synopsis... Along the northwestern periphery of an expansive upper ridge over the West, a low-amplitude midlevel disturbance and accompanying influx of midlevel moisture will overspread parts of the Northwest today. While this should support isolated high-based showers, weak buoyancy and warm EL temperatures should limit thunderstorm potential. With that said, an isolated storm or two cannot be entirely ruled out over the Cascades in OR. Elsewhere, a limited overlap of dry/windy conditions atop receptive fuels will reduce fire-weather concerns across the CONUS. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No Mesoscale Discussions are in effect as of Mon Jul 20 15:37:02 UTC 2026.

MD 1670 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR FAR SOUTHEAST MINNESOTA...EASTERN IOWA
Mesoscale Discussion 1670 NWS Storm Prediction Center Norman OK 0755 AM CDT Mon Jul 20 2026 Areas affected...Far Southeast Minnesota...Eastern Iowa Concerning...Severe potential...Watch unlikely Valid 201255Z - 201500Z Probability of Watch Issuance...20 percent SUMMARY...An isolated wind-damage threat will likely continue with a short line of strong to severe storms near the Iowa-Minnesota state line. This line will move south-southeastward across eastern Iowa over the next couple of hours. The threat is expected to be marginal and weather watch issuance appears unlikely. DISCUSSION...The latest surface analysis shows a north-to-south corridor of low-level moisture from far western Missouri northward into western Iowa, along which dewpoints are in the mid 70s F. Slightly further east, the RAP has an axis of moderate instability with MLCAPE in the 1000 to 2000 J/kg range analyzed over central Iowa. Scattered thunderstorms are ongoing along the instability gradient to the east of this axis. The storms are being supported by a subtle mid-level shortwave trough evident on water vapor imagery moving southeastward across the upper Mississippi Valley. Although forecast soundings across eastern Iowa this morning have a near-surface inversion in place, effective shear is estimated to be near 40 knots. This could support an isolated and marginal threat for severe wind gusts over the next couple of hours, especially as surface temperatures ahead of the storms begin to increase. ..Broyles/Smith.. 07/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DVN...ARX...MPX...DMX... LAT...LON 43549372 43049385 41999340 41419293 41159252 41039199 41089155 41329112 41759080 42189082 42839106 43439143 43809184 43999228 43979296 43799344 43549372 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more

MD 1671 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN UPPER PENINSULA OF MICHIGAN AND ADJACENT WISCONSIN
Mesoscale Discussion 1671 NWS Storm Prediction Center Norman OK 0837 AM CDT Mon Jul 20 2026 Areas affected...Western Upper Peninsula of Michigan and adjacent Wisconsin Concerning...Severe potential...Watch unlikely Valid 201337Z - 201530Z Probability of Watch Issuance...20 percent SUMMARY...Isolated damaging winds and marginally severe hail are possible this morning. A gradual weakening trend is anticipated and a watch is not expected. Trends will continue to be monitored. DISCUSSION...A small elevated linear segment has moved into the western Upper Peninsula of Michigan. The observed soundings from INL and APX this morning show around 7 C/km mid-level lapse rates. This activity is currently being driven by moderate low-level warm advection. With time, however, the low-level jet will weaken and veer. Elevated buoyancy will be able to sustain robust convection for another hour or two as it moves southeastward at around 35 kt. The overall expectation is for this linear segment to outpace favorable buoyancy before low-level moistening increases later today. Isolated damaging winds will be the main threat this morning, though steep mid-level lapse rates could support marginally severe hail as well. ..Wendt/Thompson.. 07/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MQT...GRB... LAT...LON 46548988 47188889 46428704 45818661 45508680 45478777 46548988 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more