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 291943 SWODY1 SPC AC 291942 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sat Mar 29 2025 Valid 292000Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE CENTRAL AND SOUTHERN GREAT PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the central/southern Plains into the mid Mississippi Valley, mainly this evening through the overnight hours. This may include an organized thunderstorm cluster across parts of Oklahoma into southeastern Kansas and western Missouri capable of producing very large hail, damaging winds, and perhaps a couple of tornadoes. ...20z Update... The Marginal Risk across portions of southeast Texas was to remove, as thunderstorm activity has moved eastward. A Marginal Risk was introduced across the Florida Keys. Otherwise, no changes were made to the Slight Risk areas across the southern/central Plains. See previous discussion for more information. ...Central Plains into the Mid Mississippi Valley... As thunderstorm activity progresses eastward through time this evening, a corridor of greater damaging wind risk may develop. CAM solutions continue to indicate upscale growth across portions of northern Oklahoma into southern Kansas and western Missouri. Should this line be able to organize and establish a strong cold pool, the potential exists for a swath of damaging wind and perhaps some significant winds given the steep mid-level lapse. Limiting factors include the displacement of the stronger low-level jet winds to the south and lagging of stronger mid-level flow across the Red River into central Oklahoma. In addition, CAM guidance is split on a more organized bowing line or a somewhat broken line of mixed mode thunderstorms. Even so, a couple of gusts 70-80 mph could not be ruled out. ...Florida Keys... Recent radar imagery has shown a couple of supercells with strengthening rotation moving northwestward near the lower Florida Keys. The environment in this region is characterized by rich moisture and storm relative helicity around 100-150 m2/s2. This will support a risk for a tornado with inclusion of a Marginal Risk with this update. ..Thornton/Smith.. 03/29/2025 .PREV DISCUSSION... /ISSUED 1134 AM CDT Sat Mar 29 2025/ ...Central/Southern Plains into the Mid Mississippi Valley... Water-vapor imagery shows a lead disturbance moving northeastward across the central Great Plains towards the Upper Midwest, while an upstream disturbance moves from eastern AZ into the southern Great Plains tonight. The primary surface low over western KS this morning is forecast to develop east-northeastward towards southern IA/northern MO by tonight. An attendant cold front will sweep southward across parts of the central/southern Plains through the period, while a dryline mixes eastward over the southern High Plains this afternoon. Surface analysis shows lower 60s dewpoints streaming northward on southerly low-level flow this morning from north TX to the KS/OK border. A substantial cap will likely inhibit robust convective development until late this afternoon or early evening, with the cold front/dryline intersection over western OK a potential location for convective initiation by 23-03Z as large-scale ascent with the trailing shortwave trough overspreads the warm sector. Moderate to strong buoyancy will likely be present across western/northern OK and southern KS, with steep mid-level lapse rates atop upper 50s to mid 60s surface dewpoints. Forecast soundings favor supercell development with activity that develops south of the front across west-central OK. Large to very large hail (potentially up to 1.5-2.5 inches in diameter) may accompany these storms early in their convective life cycle. Despite increasing CINH during the evening, lower 60s dewpoints in place with 500-mb temperatures around -15 deg C may aid the development of a tornado risk from central into northeast OK as storms mature and eventually grow upscale. Severe gusts will probably become more prevalent with time as this cluster moves east-northeast into parts of northeast OK and eventually into MO later tonight, perhaps with the wind threat slowly diminishing late. Farther south, a conditional severe threat exists south of the Red River from north TX southwestward into parts of the Concho Valley. It appears the airmass will remain capped during the day in the vicinity of the dryline, with storm development likely delayed until late evening into the overnight per recent model guidance. Very steep 700-500 mb lapse rates, strong deep-layer shear magnitudes (50 kt effective shear), and 2000-3000 J/kg MUCAPE will support a severe risk with any sustained storms. Models vary between very isolated coverage and scattered storm coverage, especially over parts of central into north TX. Given consistency in some model guidance (e.g., HRRR model run to run, GFS, ECMWF) showing some convective signal, have opted to increase hail probabilities to level-2 Slight Risk overnight. Large to very large hail is possible with the stronger storms (1 to 2.5 inches in diameter). ...Louisiana/Mississippi... A remnant MCV will continue to move northeastward this afternoon across the lower MS Valley and Mid-South. Although deep-layer shear is expected to remain fairly weak, sufficient low-level shear should be present to support some updraft organization and transient rotation with the stronger storms. Cells moving northeastward and inland over the central Gulf Coast may pose a threat for a brief tornado, as well as a localized risk for damaging gusts. $$ |
Convective Outlook Day 2
SPC Day 2 Outlook Discussion
ACUS02 KWNS 291730 SWODY2 SPC AC 291728 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sat Mar 29 2025 Valid 301200Z - 311200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS A BROAD AREA CENTERED OVER THE OHIO/MID MISSISSIPPI/TENNESSEE VALLEYS... ...SUMMARY... A widespread/substantial severe-weather episode is forecast across an area centered on the Ohio/Mid and Lower Mississippi/Lower Missouri/Tennessee River Valleys. Very large hail, damaging winds, and strong tornadoes are expected. ...Synopsis... Mid-morning water vapor imagery depicts an upper-level shortwave trough across the Southwest that is the leading impulse within a longwave trough building across the eastern Pacific/western CONUS. This wave is expected to overspread the southern/central Plains today before migrating into the Great Lakes region through the day tomorrow. A secondary disturbance is expected to move into the southern Plains late tomorrow evening into early Monday. At the surface, the surface low analyzed across KS is forecast to intensify as it moves northeast along a frontal zone into the Great Lakes in tandem with the leading upper disturbance. The intensification of the low will result in a cold frontal surge across the Midwest/OH Valley tomorrow afternoon and across the Mid-MS Valley to Texarkana region tomorrow evening. Scattered to widespread thunderstorm development is anticipated along and ahead of the frontal zone with the potential for widespread large hail/severe winds and several tornadoes. ...Central TX... Latest guidance suggests convection may be ongoing across central TX along/ahead of a migratory dryline early Sunday morning. The southern extent of a pronounced EML casts doubt on storm coverage/longevity. However, buoyancy and deep-layer wind shear should be supportive of supercells with an attendant severe hail/wind threat if mature updrafts can develop along the boundary as the primary upper-level trough axis passes over the region. ...IL, IN, and OH... Consensus among recent forecast guidance is that kinematic fields will steadily strengthen across the Midwest and middle OH River Valley regions through the day as the surface low intensifies. Increasing southerly flow ahead of the primary cold front should allow for dewpoints in the upper 50s to low 60s to spread into the region by mid-afternoon. Scattered thunderstorm development along the cold front appears likely as early as 18-20z across IL, and while a few initially discrete cells are possible, strong forcing along the front should promote upscale growth into an organized line by late afternoon. Strong low-level flow (nearly 50 knots 0-1 km BWD) may promote bowing segments and embedded mesovorticies within the line - especially across northern IN/northwest OH. 30% wind probabilities have been expanded northward to account for this potential. While this is the most probable scenario based on morning guidance, it could be complicated by any ongoing showers/thunderstorms and/or remnant outflow boundaries associated with nocturnal convection over MO late Saturday/early Sunday morning. This could limit diurnal heating/destabilization or may provide pre-frontal foci for convective initiation and promote more discrete storm modes. ...Mid-MS Valley to Texarkana region... Scattered, initially discrete supercells are expected to develop from the confluence of the OH/MS rivers southwestward into the Texarkana region Sunday afternoon along the cold front and dryline. Strong flow associated with the intensifying cyclone will promote elongated hodographs featuring nearly uni-directional wind profiles and effective bulk shear values on the order of 50-60 knots. This will promote splitting supercells with the potential for large to very large (2+ inch) hail. A more appreciable supercellular tornado threat may emerge through early evening across the lower OH Valley/mid-MS Valley where stronger veering in the lowest 1-2 km is anticipated amid weak pre-frontal isentropic ascent between 925-850 mb. While the tornado threat may be maximized through this corridor, low confidence in storm mode (due to the potential for splitting cells/destructive interactions) limits confidence in this potential to warrant higher probabilities at this time. However, upscale growth is anticipated through mid/late evening as the secondary upper disturbance migrates into the Texarkana region. Consolidation of multiple clusters into one or more organized linear segments is expected as storms push east towards the MS Valley with a gradual increase in the potential for damaging/severe winds. Additionally, low-level shear will remain favorable for embedded mesovorticies as the line pushes into western TN/northern MS/northwest AL through the overnight hours. ...Florida... A weak mid-level impulse (currently over the northern Gulf) is expected to meander across northern FL by peak heating. Somewhat strong mid-level winds (25-30 knots) associated with this feature may provide sufficient organization to thunderstorms developing across eastern central/northern FL to pose an isolated hail/wind threat. ..Moore.. 03/29/2025 $$ |
Convective Outlook Day 3
SPC Day 3 Outlook Discussion
ACUS03 KWNS 291928 SWODY3 SPC AC 291927 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Sat Mar 29 2025 Valid 311200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A LARGE PART OF THE EASTERN U.S. INTO THE CENTRAL GULF COAST... ...SUMMARY... Strong/severe thunderstorms are forecast Monday from portions of the Northeast southwestward to the central Gulf Coast region. ...Synopsis... A surface low is forecast to intensify as it moves northeastward from the Lower Great Lakes into southeast Canada through the day Monday morning in tandem with a leading shortwave trough. A trailing cold front is expected to push east/southeast into the upper OH River Valley and lower MS Valley/Southeast early Monday morning as a second low-amplitude wave traverses the eastern CONUS. Thunderstorm potential will be focused along this front as it continues to push into New England, the Mid-Atlantic, and into the southeast states through the late afternoon and evening hours. ...Central Gulf States... Strong to severe thunderstorms may be ongoing by 12z Monday as a squall line forced along the cold front continues to push southeast across MS and AL. A combination of rich low-level moisture ahead of the line, diurnal heating, strong low to mid-level flow, and broad scale ascent ahead of the secondary upper wave should help maintain convective intensity into the afternoon hours. A corridor of damaging/severe winds, and potentially embedded tornadoes, appears probable from central MS into AL and western GA. ...Central Appalachians... Thunderstorm development along the front is expected by early to mid-afternoon from the upper OH Valley southward into the Mid-Atlantic region. Returning moisture through the Carolinas northward into eastern PA/western NY, combined with mid-level lapse rates around 7 C/km, should support sufficient buoyancy for deep convection, though buoyancy values should diminish with northward extent across the central Appalachians. Moderate flow within the lowest few kilometers should support a damaging wind threat as convection matures along the front across the upper OH Valley. Further south, stronger ascent ahead of the secondary upper wave should promote better storm organization, including the potential for semi-discrete cells and/or organized linear segments. Medium-range guidance suggests low-level winds will strengthen across the Mid-Atlantic region as a weak secondary low deepens through late afternoon in the lee of the Appalachians, which may support an enlargement of the 0-3 km hodograph and a locally higher tornado threat across the Carolinas into VA. ..Moore.. 03/29/2025 $$ |
Convective Outlook Day 4-8
SPC Day 4-8 Outlook Discussion
ACUS48 KWNS 290903 SWOD48 SPC AC 290902 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0402 AM CDT Sat Mar 29 2025 Valid 011200Z - 061200Z ...DISCUSSION... Medium-range models appear to be in fairly good agreement through much of the medium-range period, with respect to large-scale pattern evolution/placement of the main synoptic-scale features. One primary difference between the GFS and ECMWF at this time is that the EC is more highly amplified with the upper pattern through the period, and thus -- in general -- depicting stronger surface features and greater flow aloft/wind shear. One result of the higher amplitude of the ECMWF manifests Day 4/Tuesday April 1. As the eastern U.S. trough moves off the Atlantic Coast, and the cold front stalls over the northern Gulf of America early, northward return of this boundary as a warm front is forecast over the southern and eventually the central Plains. Central High Plains cyclogenesis is expected along this front as it shifts northward. However, given the more amplified nature of western troughing within the ECMWF, a much stronger surface cyclone is progged by the EC as compared to the GFS (984 mb vs. 991 mb respectively). The result is much stronger low-level theta-e advection across the central/southern Plains depicted by the EC, driving a much more rapid northward advance of the warm front. Both models suggest after-dark convective development, but where the GFS depicts weaker, elevated CAPE across Kansas, the EC's more robust, potentially near surface-based CAPE suggests greater, more widespread severe potential than the GFS. At this time, a small 15% area will be introduced, centered over the mid Missouri Valley area, mainly for the potential for hail with stronger storms. Later refinements of the risk area will likely be required. Day 5/Wednesday, a widespread, potentially substantial severe event remains apparent, and with greater agreement within the models with respect to the upper trough advance and associated positioning of the surface low/cold front, greater confidence with respect to the degree of risk exists. While a very similar 15% risk area will be depicted as in yesterday's outlook, a 30% area is being introduced from Arkansas northeastward to the mid Ohio Valley. It appears that the environment will become conducive for supercells, with very large hail, damaging winds, and strong tornadoes all possible during the afternoon and evening hours. From Day 6 onward, the cold front will continue its eastward advance across the Ohio Valley and into/across the Northeast/New England. However, much slower southward progression of the cold front is expected, with an eventual drift northward as a warm front that then lingers/oscillates across the Ohio Valley/Mid South/central and southern Plains through the end of the period. This will occur as a slow-moving trough moves into the West, and eventually evolves into a cut-off low. While weak disturbances eject eastward through southwesterly flow aloft across the central U.S. -- each of which may bring rounds of convection/severe potential in the day 6-8 time frame, narrowing down specific/greater areas of potential is difficult at this time. ..Goss.. 03/29/2025
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