The Storm Prediction Center (SPC) is part of the National Weather Service (NWS) and the National Center for Environmental Prediction (NCEP). Their mission is to provide accurate forecasts and monitor the timing of thunderstorms and severe storms in the United States. The SPC provides convective outlooks on Day 1, Day 2, and Day 3 that reflect the overall level of severe weather hazard through a list of forecast statistics that identify areas at risk of mild thunderstorms and severe thunderstorms across the contiguous United State. For more information on how to read this map, please see the bottom of this page.
Convective Outlook Day 1
SPC Day 1 Outlook Discussion
ACUS01 KWNS 261253 SWODY1 SPC AC 261252 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Mar 26 2025 Valid 261300Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN PORTIONS OF WASHINGTON/OREGON... ...SUMMARY... Severe thunderstorms are expected across parts of the Pacific Northwest this afternoon and evening, with supercells possible west of the Cascades across Oregon into Washington. These storms may produce large hail, perhaps a tornado or two, and strong wind gusts. ...Pacific Northwest... A very active early season severe risk is expected regionally today. A seasonally strong upper low over the coastal Pacific Northwest will shift eastward today, highlighted by a 100+ kt mid-level speed max that will overspread coastal areas by evening. Strong height falls will similarly spread across this region and the associated synoptic cold front should arc from off the Washington Coast to southward along the Oregon Coast by evening. Low-level mean-mixing ratios are notably high, as compared to typical daily climatological values (highest 5-10%), this morning based on 12z observed soundings from Salem and Medford, Oregon. Large-scale forcing for ascent will contribute to a further moistening of profiles and PW values may approach 1 inch prior to convective initiation. Cold mid-level temperatures and a plume of steepening mid-level lapse rates will also notably overspread the region. Of particular concern are the cold mid-level temperatures, and the steep lapse rate plume that will overspread this region. Forecast soundings suggest convective temperatures should be breached by 21-22z west of the Cascades, and surface-based CAPE should reach/exceed 1000 J/kg coincident with a favorably sheared environment for organized, rotating updrafts. Isolated to scattered robust convection seems likely to develop by 21-22z across western Oregon, immediately ahead of the strong forcing. This activity should grow upscale and develop north-northeastward ahead of the approaching speed max, with profiles favoring supercell development. Hail should be common with this activity and the strongest updrafts may generate quite large hailstones, possibly exceeding golf ball size, or even larger with a few of the most intense storms. Some tornado risk will also exist, particularly where low-level winds maintain at least a modest easterly component. Damaging winds may also occur. ...Texas Lower Rio Grande River Valley... Water vapor imagery depicts a substantial sub-tropical cirrus plume from the southern Baja Peninsula, across Mexico toward the lower Rio Grande Valley. A weak disturbance will approach the international border through mid day, and this will draw a substantial moisture plume across South Texas. Forecast soundings exhibit modest lapse rates despite the moistening profiles. While forecast shear is not particularly strong, especially with northward extent, some organization is possible and this activity could generate gusty winds and/or hail. Otherwise, a considerable amount of convection is expected across this region which may tend to disrupt and limit organizational potential. ..Guyer/Bentley.. 03/26/2025 $$ |
Convective Outlook Day 2
SPC Day 2 Outlook Discussion
ACUS02 KWNS 260614 SWODY2 SPC AC 260613 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0113 AM CDT Wed Mar 26 2025 Valid 271200Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SOUTHERN TEXAS... ...SUMMARY... Scattered severe thunderstorms are possible Thursday across parts of the southern High Plains, and into southern Texas, as well as over the Lower Missouri/Mid-Mississippi Valleys. ...Southern High Plains across southern Texas... Showers and thunderstorms are forecast to be ongoing early in the period, as a slow-moving southern-stream trough moves eastward across northern Mexico and Texas through the period. Local risk for hail/wind may be ongoing with these storms. During the afternoon, isolated high-based convection may develop across parts of southeastern New Mexico and Far West Texas. Despite modest CAPE/shear, the deep/dry boundary layer may support gusty/damaging winds with any stronger storm. Farther east, along the Rio Grande, storms will likely develop over higher terrain on the Mexican side of the river, and may shift into adjacent portions of Texas with time. Meanwhile, remnant outflow from earlier convection may focus new storm development, as moderate instability develops due to the moist boundary layer residing beneath steep mid-level lapse rates associated with the upper system. Low-level southeasterlies veering with height, and increasing to 30-plus kt at mid levels, will support organized/rotating storms, the strongest of which will be capable of all-hazards severe potential. Risk will likely continue through the evening, spreading eastward into southeastern Texas with time. ...Middle Missouri Valley area eastward to the Lower Ohio Valley... As a warm front advances slowly northward across the central Plains and Midwest, several clusters of showers and scattered thunderstorms are forecast to develop, and shift east-southeastward within the prevailing west-northwesterlies aloft. Isolated afternoon surface-based storms may develop over the north-central Kansas vicinity, where risk for a few strong wind gusts may occur, along with potential for hail. However, more widespread convection during the period is forecast north of the warm front. Steep lapse rates above the low-level stable air, and amply strong mid-level flow, suggests potential for severe-caliber hail. ..Goss.. 03/26/2025 $$ |
Convective Outlook Day 3
SPC Day 3 Outlook Discussion
ACUS03 KWNS 260733 SWODY3 SPC AC 260732 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 AM CDT Wed Mar 26 2025 Valid 281200Z - 291200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NEBRASK VICINITY...AND FROM EASTERN TEXAS TO THE LOWER MISSISSIPPI VALLEY... ...SUMMARY... A few strong/severe storms may occur from parts of East Texas to the Lower Mississippi Valley, and also across portions of the Nebraska vicinity overnight. ...Eastern Texas to the Lower Mississippi Valley... Thunderstorms are forecast to be ongoing across eastern portions of the southern Plains, in conjunction with the slow-moving southern-stream trough crossing the area. As the trough continues moving slowly east-northeastward, daytime heating away from ongoing clouds/convection will allow the airmass to destabilize, supporting additional convective development. Mid-level flow will remain rather weak across the area. However, ahead of the low, moderate low-level southeasterlies veering to southwesterly through mid levels should result in shear sufficient for organized/weakly rotating storms. Convection will spread into Arkansas/Louisiana through the afternoon and evening, accompanied by the risk for locally gusty winds, and possibly a brief tornado or two, warrant inclusion of low (5%) severe-weather probability at this time. ...Nebraska vicinity... As a weak frontal low shifts eastward out of the central High Plains into western Kansas, in response to a short-wave trough crossing the Rockies, elevated storms seem fairly likely to develop in a zone of focused warm advection northeast of the low, across the Nebraska vicinity. Relatively steep lapse rates combined with moderate mid-level lapse rates/instability and moderate mid-level southwesterlies suggest potential for a few stronger storms to produce hail, during the overnight hours. ..Goss.. 03/26/2025 $$ |
Convective Outlook Day 4-8
SPC Day 4-8 Outlook Discussion
ACUS48 KWNS 260906 SWOD48 SPC AC 260904 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Wed Mar 26 2025 Valid 291200Z - 031200Z ...DISCUSSION... Medium-range models appear to be in reasonable agreement through Day 6 (Monday March 31), with respect to synoptic-scale features. Divergence in solutions increases thereafter, particularly with the strength/progression of the next trough moving across the western CONUS and into the Plains. As such, no risk areas will be considered beyond Day 6/Monday. Day 4/Saturday, a couple of small-scale vorticity maxima/short-wave troughs are forecast to cross the central portion of the country, ahead of the stronger system advancing across the West. This feature is forecast to reach the High Plains overnight, as a surface low moves across the Kansas/Oklahoma vicinity. Models continue to indicate that capping will remain an issue, hindering convective development in the warm sector ahead of the low (across the Kansas/Oklahoma/western Missouri/western Arkansas area) at least until after dark/overnight. While some severe threat may evolve with storms which should be slightly elevated for the most part, risk does not appear sufficient to warrant inclusion of a 15% risk area. Day 5/Sunday, more substantial cyclogenesis is expected, though differences exist between the models in terms of timing/location of the developing low -- and associated cold front. Nonetheless, substantial warm-sector destabilization is forecast to occur from Missouri/Arkansas/eastern Texas eastward across the Mississippi Valley during the day, and extending eastward across the Midwest/Ohio and Tennessee Valleys. This will support scattered thunderstorm development, within an increasingly sheared environment. By early afternoon, severe/supercell storms are expected, accompanied by the risk for very large hail, damaging winds, and a few tornadoes. Storms should spread southeast of the Ohio and Mississippi Valleys overnight, accompanied by ongoing severe risk. Day 6/Monday, risk will likely have shifted to near and east of the Appalachians, and southward to the Gulf Coast area, as the surface cold front advances. Destabilization ahead of the front will support continuation of severe risk given favorably strong flow aloft, with storms reaching/moving off the Gulf and Atlantic Coasts late in the period. ..Goss.. 03/26/2025
Convective Weather Outlook Legend Data
- TSTM (light green) – General or non-severe thunderstorms – Delineates, to the right of a line, where a 10% or greater probability of thunderstorms is forecast during the valid period.
- 1-MRGL (dark green) – Marginal risk – An area of severe storms of either limited organization and longevity, or very low coverage and marginal intensity.
- 2-SLGT (yellow) – Slight risk – An area of organized severe storms, which is not widespread in coverage with varying levels of intensity.
- 3-ENH (orange) – Enhanced risk – An area of greater (relative to Slight risk) severe storm coverage with varying levels of intensity.
- 4-MDT (red) – Moderate risk – An area where widespread severe weather with several tornadoes and/or numerous severe thunderstorms is likely, some of which should be intense. This risk is usually reserved for days with several supercells producing intense tornadoes and/or very large hail, or an intense squall line with widespread damaging winds.
- 5-HIGH (magenta) – High risk – An area where a severe weather outbreak is expected from either numerous intense and long-tracked tornadoes or a long-lived derecho-producing thunderstorm complex that produces hurricane-force wind gusts and widespread damage. This risk is reserved for when high confidence exists in widespread coverage of severe weather with embedded instances of extreme severe (i.e., violent tornadoes or very damaging convective wind events).
This data is courtesy from the Storm Prediction Center