
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Mon Apr 20 2026 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE HIGH PLAINS OF NEBRASKA SOUTH INTO THE TEXAS PANHANDLE... ...SUMMARY... Severe thunderstorms capable of hail and gusty winds may develop during the late afternoon and evening across portions of the High Plains. Elsewhere, thunderstorms will be possible across the northern Gulf Coast and portions of the Ohio Valley. ... Synopsis ... A shortwave trough will eject northeast out of the basal region of the western CONUS trough and into the northern Plains on Wednesday. As this happens, strengthening southerly/southwesterly midlevel flow will overspread much of the High Plains. A surface cyclone over eastern Montana will gradually deepen as it slowly moves east. ... Central High Plains south into the southern High Plains ... As the Montana surface cyclone gradually deepens on Wednesday, Gulf moisture will be drawn northward into the central and northern Plains. As the upper trough approaches the region during the late afternoon/evening, modest height falls are expected to overspread a sharpening dryline across far eastern Colorado or western Nebraska south into the Texas Panhandle. Kinematic profiles up and down the dryline show ample vertical shear for supercells capable of producing hail and gusty winds. However, considerable uncertainty remains regarding thunderstorm coverage owing to the significant differences in the depth and quality of the boundary layer moisture return noted in the 20260420/00Z guidance suite. For example, the NAM is nearly 5F more moist along the dryline across portions of Nebraska than global models. That said, pattern recognition and 00Z RRFS suggest that at least a couple of storms should develop along the dryline from Nebraska south into the eastern Texas Panhandle. Deep-layer flow will largely parallel the dryline during the afternoon which should preclude much eastward advancement. A 5% unconditional risk area has been added to account for this potential. ... Elsewhere Across the CONUS ... Thunderstorms may be ongoing at the start of the forecast period and persist into the early afternoon across portions of the northern Gulf Coast. The thunderstorm potential should wane with time as increasing midlevel heights suppress large-scale ascent. Additionally, modest low-level moisture and weak instability may support a few lightning strikes within a weak surface boundary across the Ohio Valley. ..Marsh.. 04/20/2026Read more

Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0129 AM CDT Mon Apr 20 2026 Valid 211200Z - 221200Z ...Synopsis... Upper-level ridging will gradually slide east over the Great Plains on D2/Tuesday as a closed upper-level low moves onshore across the West Coast. At the surface, high pressure will build into the Southeast while a frontal system advances across the northern Great Plains and Upper Midwest. ...Portions of Florida into southern Georgia... Sustained easterly winds of 10-15 mph along the southeastern periphery of high pressure building into the Southeast will overlap reduced RH of 20-30% across much of the Florida Peninsula and into southern Georgia Tuesday afternoon. Continued dry conditions amid extreme to exceptional drought continues to promote receptive fuels across this region, with ERCs currently at or above the 95th percentile. This combination is expected to support elevated fire weather concerns for at least a few hours. While winds are currently forecast to remain below critical criteria, locally critical conditions may be possible given the dryness/receptiveness of fuels and potential for occasional wind gusts to 20 mph. ..Chalmers.. 04/20/2026 ...Please see www.spc.noaa.gov/fire for graphic product...Read more

Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0128 AM CDT Mon Apr 20 2026 Valid 201200Z - 211200Z ...Synopsis... Upper-level ridging will gradually shift eastward from the Rockies into the Plains through today as an upper-level trough departs the East Coast and a second, closed upper trough approaches the West Coast. Surface high pressure will shift east over the Southeast/Mid-Atlantic while a lee trough deepens along the central/northern High Plains. ...Portions of the central High Plains... A deepening lee trough along the central High Plains will support strengthening westerly downslope winds to the west of the trough axis across portions of southeastern Wyoming into southwest South Dakota and much of western/central Nebraska. Farther south/east, high pressure over the Lower Mississippi Valley in conjunction with the lee trough will yield a tightened surface pressure gradient and strengthening southerly winds from the TX/OK Panhandle vicinity northeastward into central Kansas and south-central Nebraska. Sustained winds of 15-20 mph are expected within both of these regimes. RH minimums of 10-15% (locally lower) are expected across southeast Wyoming, southwest South Dakota, and western Nebraska where downslope wind will depress moisture content within an antecedent dry air mass. Farther south/east, the northern fringe of returning moisture may limit RH reductions to some degree, but RH minimums are still forecast to fall to 15-25% southeastern Colorado northeastward into south-central Nebraska. With dry, receptive fuels across much of the region, this will support widespread elevated fire weather conditions for a few hours this afternoon. Locally critical conditions will also be possible in the lee of the Laramie Mountains in southeastern Wyoming where winds may occasionally gust to 30-35 mph. ...Portions of the Southeast... A dry air mass will continue to reside across much of the Southeast where fuels remain exceptionally dry (ERCs above the 95th percentile) amid continuing drought. Sustained northeasterly winds of 10-15 mph along the southern periphery of surface high pressure are forecast to overlap minimum RH values of 15-25% across much of the Florida Panhandle and adjacent areas of southern Alabama/Georgia. Farther north, modest westerly/northwesterly downslope winds of 10-15 mph are forecast behind a dry, secondary cold frontal passage, with minimum RH of 20-30% (locally lower) expected. This combination of winds/RH is expected to support elevated fire weather concerns across much of the Southeast this afternoon. ...Portions of New Mexico into eastern Arizona... Low to mid-level moisture return is forecast across southern Texas into portions of the Southwest through this afternoon. Although forcing for ascent will remain modest under an upper-level ridge, a combination of localized orographic ascent, deeply mixed boundary layers with minimal inhibition, and a weak, subtle mid-level shortwave trough will support isolated thunderstorm development this afternoon. Slow storm motions (around 10 kts) will likely support pockets of wetting precipitation, but PWAT values of 0.4-0.7" atop a dry sub-cloud layer will likely support dry lightning strikes while largely limiting precipitation. With regional ERCs near the 75th to 80th percentile, lightning ignitions appear possible. While prevailing flow is forecast to remain weak, gusty outflow winds may create erratic fire behavior with any new ignitions. ...Portions of the Upper Midwest... A tightened surface pressure gradient will promote sustained southwesterly winds of 20-25 mph, with the potential for gusts to 30-35 mph, across portions of the Upper Midwest, especially across the eastern Dakotas and much of Minnesota. RH values are forecast to fall to 25-30% this afternoon, with lower values possible should forecast cloud cover clear more quickly this morning/afternoon. This combination of wind/RH may promote locally elevated fire weather concerns this afternoon, especially in pockets of drier fine fuels. Recent precipitation across portions of this area along with marginal fuel receptiveness and uncertainty regarding cloud cover preclude the addition of Elevated highlights at this time. ..Chalmers.. 04/20/2026 ...Please see www.spc.noaa.gov/fire for graphic product...Read more

Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1247 AM CDT Mon Apr 20 2026 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will be possible across the western CONUS, the south-central CONUS, and the southern Great Lakes on Tuesday. Potential for severe weather appears low. ... Synopsis ... Midlevel ridging will be in place from the eastern Great Basin into the Plains at the start of the forecast period, while persistent northwesterly flow aloft continues across the Upper Midwest and Ohio Valley. Farther west, an upper trough will gradually advanced inland across California into the Great Basin by the end of the period. At the surface, a broad area of high pressure centered over the Southeast and adjacent Atlantic will maintain southerly flow across the central US. This will promote a gradual moisture recovery across the central Plains into the southern Great Lakes. A weak frontal boundary pushing south through portions of the central Plains and Great Lakes will denote the northern edge of the moisture return. ... Lower Great Lakes ... Thunderstorm development along the frontal zone may be delayed until later in the day or evening as moisture slowly returns northward. While relatively cold temperatures aloft should support steep lapse rates, the quality and depth of the boundary-layer moisture is expected to be the biggest unknown. The NAM is the most aggressive with the depth and quality of the moisture return, and if moisture quality is close to what is shown in the NAM, enough instability should materialize to take advantage of the stronger vertical shear to support a few organized cells capable of gusty winds or small hail. However, most model guidance is less aggressive with the quality of the moisture return so no probabilities have been added at this time. ... South-central US ... Convection will likely be ongoing at the start of the forecast period. Modest vertical shear and elevated instability may support a couple strong thunderstorms capable of hail and gusty winds. However, overall thunderstorm intensity should wane through much of the period as upper ridging overspreads the region. ... Western US ... As the upper trough moves inland, ascent will increase across the Pacific Northwest, northern California, and portions of the Great Basin. Within the Central Valley and nearby terrain, pockets of diurnal heating, combined with cool midlevel temperatures may support isolated thunderstorm development during the afternoon. Despite this modest instability, weak vertical shear should limit any organized severe potential. ..Marsh.. 04/20/2026Read more

Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 PM CDT Sun Apr 19 2026 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe storms are not expected today. ...Synopsis... An upper trough will exit the northeastern states today, with northwest flow aloft extending from the northern Plains to the East Coast. Upper ridging will occur over the Rockies, while a large upper trough slowly approaches the West Coast. At the surface, high pressure will result in relatively stable conditions for much of the central and eastern CONUS, with centers over the Mid Atlantic and near the northern Gulf Coast. In the wake of the eastern trough, winds just off the surface will maintain a zone of elevated moisture and instability over much of TX, where scattered showers and storms will be most likely. Weak instability will preclude any severe storm chances there. To the west, cooling aloft with the approaching upper trough will support weak instability into parts of OR and WA, with isolated late day thunderstorms possible over portions of the Cascades. Small/non-severe hail cannot be ruled out, along with locally gusty winds mainly in the 00-03Z time frame. ..Jewell/Chalmers.. 04/20/2026Read more