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ACUS01 KWNS 311251

SWODY1

SPC AC 311250



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0750 AM CDT Sun Mar 31 2024



Valid 311300Z - 011200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN

MISSOURI INTO THE OHIO VALLEY...



...SUMMARY...

Scattered thunderstorms are expected today along a corridor from

northern Missouri into the Ohio Valley, with large hail expected. 

Damaging gusts are possible, and a marginal tornado threat also

exists.



...Synopsis...

The major mid/upper-level influence on convective potential today,

and for the next few days, will be a high-amplitude, positively

tilted, synoptic-scale trough now extending from the northern

Rockies southwestward to offshore from southern CA.  Two

accompanying, closed cyclones were noted in moisture-channel imagery

-- the largest centered about 150 nm west of LAX, the smaller one

over west-central NV.  Both cyclones are forecast to devolve to open

shortwave troughs through the period, as an upstream perturbation --

now over the interior Northwest -- digs southward in the backside

cyclonic-flow field.  Meanwhile, the synoptic trough itself will

shift eastward by 12Z to an axial position near DIK-LND-BCE-YUM,

then offshore from central/southern Baja.  Ridging aloft will

amplify slightly and drift eastward across the central/southern

Plains. 



At the surface, 11Z analysis showed a low over extreme western KS,

with quasistationary to slow-moving warm front extending across

central parts of KS/MO to near SDF and central WV.  The eastern part

of this boundary may be shunted southward over the middle Ohio

Valley and WV today by precip.  The KS low is expected to ripple

east-northeastward on the northward-drifting warm front toward MKC,

and weaken through the period, with the warm front reaching perhaps

80-120 nm north of its initial position in MO/IL/IN.  Meanwhile, lee

cyclogenesis will occur over eastern CO, at or near a lee trough

intersection with the front.  The resulting low should migrate along

the boundary tonight, across southwestern/central KS.  A dryline was

analyzed from a frontal intersection near GBD across the TX South

Plains and Permian Basin to the Big Bend area.  The dryline should

mix eastward this afternoon to western OK and west-central TX,

before retreating westward overnight, and is expected to remain

capped for deep convective potential this period.



...MO to central Appalachians...

An ongoing, broken swath of precip, with widely scattered

thunderstorms, was apparent in radar composites from southern IN

into portions of WV.  This activity should shift east-southeastward

through the remainder of the morning and continue largely as

non-severe.  However, isolated large hail or strong gusts may occur

from any sustained, relatively discrete activity near the southern

part of the precip plume.



The main convective episode should occur from around midafternoon

into this evening, as scattered thunderstorms develop near the

front.  With a strongly front-parallel component to mean flow,

activity should move along or just north of the surface boundary,

offering large hail and sporadic damaging to marginally severe

gusts.  Local boundary processes (e.g., interaction between storm

and vorticity-rich outflow boundary or front) may alter local

low-level shear favorably enough for some tornado potential, though

this threat appears isolated and conditional, given the lack of

greater boundary-layer moisture.  



Although weak height rises are forecast across the region as the

synoptic ridge to the west amplifies, associated effects on

large-scale motion should be too small to impact convective

potential.  Diurnal heating and moist advection will boost theta-e

enough to remove most or all MLCINH along and just south of the

front, with convergence on/near the front being the primary

convective forcing.  Surface dewpoints commonly will reach the upper

50s to low 60s F in the warm sector.  Modified forecast soundings

depict 1500-2000 J/kg MLCAPE over near-frontal parts of MO this

afternoon, decreasing to an eastward-narrowing corridor of 500-1200

J/kg peak MLCAPE over the Ohio Valley and into the WV/western VA

uplands where weaker low- and middle-level lapse rates will be

found.  Though modest near-surface flow will limit lower boundary-

layer hodograph size, deep shear will be more than adequate for

supercells, with effective-shear magnitudes commonly 50-60 kt. 

However, upscale clustering and mixed modes are also possible.



..Edwards/Leitman.. 03/31/2024



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