SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 PM CDT Mon Apr 01 2024
Valid 012000Z - 021200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL
AND NORTHEASTERN OKLAHOMA...AND INTO FAR NORTH-CENTRAL TEXAS...
...SUMMARY...
Severe thunderstorms with very large hail (2-3 inch diameter or
greater), damaging gusts (60-80 mph) and a few tornadoes
(potentially up to EF2) are expected this afternoon into tonight
from north Texas and Oklahoma into the lower Ohio River Valley.
...Discussion...
Current forecast reasoning and outlook areas remains generally in
line with prior outlooks, with widespread/all-hazards severe risk
from the southern Plains into the Ohio Valley.
The main change in the current outlook update is a westward
adjustment of thunder/severe probability lines across the Big
Country and Concho Valley of Texas, where storms have initiated
along a developing dryline a bit earlier, and farther west, than
previously anticipated.
Otherwise, the outlook remains largely unchanged at this time, aside
from minor line tweaks to account for current convective
evolution/development.
..Goss.. 04/01/2024
.PREV DISCUSSION... /ISSUED 1128 AM CDT Mon Apr 01 2024/
...Synopsis...
Embedded speed maxima (90-100+ kt 500 mb) from southern NM/far west
TX to northwest Mexico will eject northeastward to OK this evening
and MO overnight. An associated lee cyclone will deepen this
afternoon across the TX South Plains and then progress into
northwest OK this evening and the mid MS Valley by the end of the
period. A broad/moist warm sector is in place from the southern
Plains to the mid MS/lower OH Valleys, beneath a warm elevated mixed
layer with 8-9 C/km midlevel lapse rates. The cap will weaken
through the afternoon from the west, with thunderstorm initiation
becoming likely by mid afternoon along a surface front from KS into
MO/IL, and mid-late afternoon along the dryline from western/central
OK into northwest TX.
...KS/MO/IL/IN through tonight...
Scattered thunderstorm development is likely starting mid afternoon
along the baroclinic zone from KS into MO, and storms will
subsequently spread eastward along the warm front from MO into
IL/IN. The environment will favor supercells capable of producing
very large hail (2-3 inches in diameter) and a few tornadoes, with
an isolated strong tornado possible. Storm mode will become messier
into the overnight hours with upscale growth into clusters/line
segments, with an increase in the threat for damaging winds (60-80
mph), and a continued threat for tornadoes (possibly up to EF2) with
embedded/QLCS circulations.
...OK/TX this afternoon into early tonight...
The elevated mixed layer and associated cap, along with widespread
clouds, will tend to delay surface-based storm development until
mid-late afternoon, when forcing for ascent increases from the
southwest with the approach of the mid-upper jet streak. By about
21z, scattered thunderstorm development is expected along the
dryline from northwest TX into western OK, and storms will spread
quickly northeastward into central/eastern OK through this
evening/early tonight. Steep midlevel lapse rates and
boundary-layer dewpoints in the mid-upper 60s will contribute to
MLCAPE of 2000-3000 J/kg, in an environment with very strong
deep-layer shear/long hodographs favorable for multiple supercells
with very large hail (3 inches in diameter or greater). The
magnitude of the tornado threat is a bit less certain, given a
weakness in the low-level shear until a more consolidated low-level
jet response begins by late evening, when storm mergers and upscale
growth become more probable into eastern OK/northwest AR/southwest
MO early tonight. However, given the very strong flow and
seasonably rich low-level moisture, there will be the potential for
a couple of strong (roughly EF2) tornadoes late this afternoon into
tonight.
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