
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0216 AM CDT Mon Apr 13 2026 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTION OF THE SOUTHERN PLAINS INTO SOUTHERN WISCONSIN... ...SUMMARY... Severe thunderstorms posing a risk for large hail and strong wind gusts will be possible across portions of the southern Plains toward the Great Lakes on Wednesday afternoon and evening. ...Southern Plains to Great Lakes... An upper trough will move from the Plains to the MS Valley vicinity on Wednesday. As associated corridor of enhanced southwesterly deep-layer flow will overspread a moist/unstable airmass ahead of a surface dryline. The southern Plains portion of the dryline will not move too much on Wednesday. However, the northern extent of this boundary will intersect a weak surface low moving from the Lower MO Valley toward Lake Michigan. This portion of the boundary will advance eastward toward the MS River during the evening/overnight hours. Areas of showers and thunderstorms may be ongoing across portions of the region Wednesday morning. As a result, there is uncertainty regarding how the boundary layer may recover/destabilize during the afternoon. Nevertheless, at least pockets of moderate destabilization (1000-2000 J/kg MLCAPE) are expected within a corridor along and east of the surface boundary. Effective shear magnitudes greater than 40 kt will be sufficient for organized convection, with large hail and strong wind gusts being the primary hazards. ..Leitman.. 04/13/2026Read more

Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0104 AM CDT Mon Apr 13 2026 Valid 141200Z - 151200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF IOWA INTO NORTHERN ILLINOIS AND SOUTHERN WISCONSIN... ...SUMMARY... Isolated to scattered severe thunderstorms are expected on Tuesday and Tuesday night from the Southern Plains to the Great Lakes. Large to very large hail, a few tornadoes, and damaging wind gusts will be possible, particularly across parts of eastern Iowa, northern Illinois, and southern Wisconsin. Additional strong storms, mainly producing strong wind gusts, will be possible across parts of the Northeast. ...Synopsis... A broad swath of enhanced deep-layer southwesterly flow will overspread the southern High Plains to the Great Lakes on Tuesday. An upper shortwave trough over the Great Basin will slowly pivot east through the period, emerging over the central/southern High Plains by Wednesday morning. A weak shortwave impulse is also forecast to move across the northern Plains and Upper Midwest. At the surface, low pressure will be centered over the Mid-MO Valley for much of the period, with a warm front extending east/northeast from north-central IA into southern WI and central Lower MI. Meanwhile, a dryline will extend southwest across eastern KS into western TX. Ahead of these boundaries, a seasonally moist airmass will be in place, with mid-60s dewpoints common. The aforementioned surface boundaries will become a focus severe thunderstorm development Tuesday afternoon into the nighttime hours. ...Mid-MS Valley and Great Lakes vicinity... A severe risk is expected to develop by late afternoon within the warm frontal zone from Iowa into northern IL/southern WI in a persistent warm advection regime. While height tendencies are forecast to remain mostly neutral, low-level convergence along the boundary and a glancing influence from a weak shortwave impulse migrating across the northern Plains into northern MN/Upper MI should provide focused ascent. A southwesterly 850-700 mb jet is also forecast to increase across the region by late afternoon into evening. Cool temperatures aloft (around -16 C at 500 mb) and steep midlevel lapse rates atop a moist boundary layer will support MLCAPE around 2000-3000 J/kg amid elongated/straight hodographs. As a result, large to very large hail will be possible with initial supercell thunderstorms. Storm motion and southwesterly deep-layer flow may result in convection moving to the cool side of the warm front. Even so, elevated storms will pose a risk for significant hail. With time, and as the low-level jet increases during the evening, convection may consolidate/grow upscale into one or most bowing segments and progress eastward into Lower MI/IN/OH, posing a continued risk for hail and an increasing risk for damaging wind gusts. Any supercells that develop and can be sustained within the warm sector will also pose a risk for a few tornadoes (some strong), very large hail and damaging gusts. ...Southern Plains into eastern KS/western MO... Moderate destabilization is forecast along the surface dryline by afternoon. Strong heating along/just west of the dryline will promote mixing, while low-level confluence and subtle height falls (by 21-00z) provide sufficient forcing for ascent for isolated thunderstorm development. Supercell wind profiles will be present amid steep midlevel lapse rates and elongated hodographs. Large to very large hail, locally strong wind gusts and a couple of tornadoes will be possible. Storms should develop northward during the evening into eastern KS and western MO as the low-level jet increases. ...Northeast... Rounds of thunderstorms are expected during the afternoon and evening within a warm advection regime. MLCAPE should increase to around 1000 J/kg within a moistening low-level airmass. Strong deep-layer westerly flow and steepening low-level lapse rates will support isolated strong wind gusts across the region. ..Leitman.. 04/13/2026Read more

Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Apr 13 2026 Valid 141200Z - 151200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST COLORADO AND ADJACENT HIGH PLAINS... ...Synopsis... The progression of the upper trough in the Southwest/southern High Plains is expected to slow on Tuesday. The trough may not eject into the Plains until early Wednesday morning. A surface low will deepen in the central High Plains. ...Southeast Colorado and vicinity... A similar setup to Monday is expected, though the location of the trough will bring better alignment of stronger mid-level winds to the region. The deepening surface low will further increase surface wind speeds to 20-25 mph. RH of around 15% appears likely. Farther east into Kansas, the surface winds will be similarly strong along with a very dry airmass (RH perhaps nearing 10% in some locations). Recent rainfall should mitigate some fire weather risk with eastward extent. Critical fire weather is expected. ...Parts of the Southwest into the southern High Plains... The base of the trough over this region along with a moderately strong surface pressure gradient will promote 15-20 mph winds. RH will be somewhat uncertain given the expected mid-level clouds. However, around 20% is possible for broad portions of the region. Elevated fire weather is forecast during the afternoon. ...Mid-Atlantic... Dry return flow will continue in the Mid-Atlantic. 10-15 mph winds around the surface high are probable during the afternoon. 25-30% RH will also occur. Despite the marginal meteorological conditions, very dry fuels will support an elevated fire weather threat. ..Wendt.. 04/13/2026 ...Please see www.spc.noaa.gov/fire for graphic product...Read more

Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Apr 13 2026 Valid 131200Z - 141200Z ...CRITICAL FIRE WEATHER AREA FOR EASTERN WYOMING...SOUTHWESTERN SOUTH DAKOTA...NORTHWESTERN NEBRASKA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN COLORADO AND ADJACENT HIGH PLAINS... ...Synopsis... Continued southwesterly flow aloft is expected today across much of the central/southern Plains. A shortwave trough is expected to approach the southern Plains very late in the period. A weaker shortwave trough in the central Northern Plains will also be present. At the surface, a broad area of low pressure will exist east of the terrain. ...Eastern Wyoming into western South Dakota and Nebraska... The northern stream mid-level jet will be favorably timed with afternoon heating/minimum RH. This feature, coupled with the surface trough to the east, will drive 20-25 mph winds in eastern portions of Wyoming and adjacent western South Dakota and Nebraska. RH will likely fall to 10-15%. Critical fire weather is expected for a few hours during the afternoon. Farther south into the Front Range, winds will be weaker leading to elevated fire weather. ...Southeast Colorado and vicinity... The position of a modest surface low in southeast Colorado will promote surface winds of around 20 mph despite the stronger mid-level winds lagging farther southwest. Terrain enhancement could also lead to local corridors of stronger winds. RH of around 15% is expected during the afternoon. These conditions will support critical fire weather. ...Piedmont...southern Appalachians... Dry return flow around a surface high pressure system will promote 10-15 mph winds within parts of the southern Appalachians and the Piedmont region. RH of near 20% is possible in parts of the Mid-Atlantic though higher values of 25-35% are expected with southward extent. Given how dry fuels are, elevated fire weather conditions are expected. ..Wendt.. 04/13/2026 ...Please see www.spc.noaa.gov/fire for graphic product...Read more

Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Mon Apr 13 2026 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MISSISSIPPI RIVER VALLEY... ...SUMMARY... Severe thunderstorms are likely across the Upper Mississippi Valley and Great Lakes region with potential for large to very large hail, damaging wind, and tornadoes. A more conditional and isolated risk for severe storms is possible across portions of the southern Plains late this afternoon and evening. ...Synopsis... Early-morning water-vapor imagery depicts an upper trough with multiple embedded vorticity maxima over the Great Basin. While the primary upper wave will remain over the West for today, a leading impulse is forecast to eject towards the northern Plains and into the Great Lakes through tonight. At the surface, a weak lee cyclone over the central High Plains will migrate northeastward in tandem with the upper impulse, likely reaching the southern MN vicinity by early evening. As this occurs, a plume of mid-60s dewpoints will spread north into the upper MS Valley along and south of a warm front. Scattered thunderstorm development along and north of the warm front is anticipated by late afternoon as forcing for ascent gradually increases. Elsewhere, more isolated strong to severe thunderstorms are possible across portions of TX and OK where deep mixing along a dryline may result in sustained deep convection. ...Upper MS Valley... A combination of shortwave ridging and capping at the base of an EML will limit thunderstorm development through much of the day across southern MN into central WI. This will allow for continued moisture return as a warm front lifts into the region with MLCAPE values forecast to reach 2000-2500 J/kg by around 21 UTC. Thunderstorm development will become increasingly probable through the 21-00 UTC period as isentropic ascent strengthens ahead of the approaching upper disturbance. Lingering inhibition coupled with 45-50 knot effective bulk shear should promote initially discrete supercells along or just north of the surface boundary. Hodograph elongation appears favorable for a large hail threat, possibly as large as 2-3 inches with the more robust cells. Additionally, enhanced low-level SRH along the frontal zone may result in a corridor of relatively higher tornado potential if convection can remain rooted along the boundary. While the overall environment appears very favorable for intense convection, east/northeasterly storm motions along or just north of the warm front will likely promote storm advection towards the cool side of the boundary and clustering/upscale growth through the evening. This, combined with capping over the remainder of the warm sector, limits confidence in a more widespread tornado threat, and could modulate the potential for significant (2+ inch) hail within a few hours after convective initiation. Nonetheless, a corridor of higher hail potential remains evident in latest guidance along and just north of the warm front where discrete supercells are most probable. 30% hail probabilities have been shifted to reflect a southward trend in frontal placement noted in most recent guidance. ...Southern Plains... A moist and very unstable air mass will remain in place across TX and OK today with MLCAPE values expected to increase to around 2500 J/kg by late afternoon. Ample diurnal heating/mixing on the western periphery of the moisture plume will likely result in weak, high-based convection by mid to late afternoon. Easterly storm motions may promote downstream intensification as convection migrates towards richer low-level moisture, but this will be conditional on convection remaining sustained long enough to realize the favorable thermodynamic environment. If this can occur, deep-layer shear values on the order of 40 knots should promote organized convection - likely in the form of supercells - with an attendant threat for all hazards, including very large hail. While both global and CAM ensemble guidance hint at this potential, the lack of appreciable lifting mechanisms (aside from the dryline circulation/boundary-layer mixing) casts considerable uncertainty on overall storm coverage. ..Moore/Wendt.. 04/13/2026Read more