SPC 2000Z Day 1 Outlook
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.
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