ACUS02 KWNS 211725

SWODY2

SPC AC 211723



Day 2 Convective Outlook  

NWS Storm Prediction Center Norman OK

1223 PM CDT Sat Mar 21 2026



Valid 221200Z - 231200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO

VALLEY INTO THE NORTHERN MID ATLANTIC...



...SUMMARY...

Scattered strong to severe thunderstorms with large hail, damaging

wind gusts, and possibly some tornado threat are expected on Sunday

afternoon and evening across parts of the Ohio Valley into the

northern Mid Atlantic region.



...Synopsis...

A mid/upper-level shortwave trough is forecast to gradually amplify

on Sunday, as it moves from the northern Plains towards the Great

Lakes region. This amplification will occur within a broader

west-northwesterly flow regime, with relatively strong deep-layer

flow expected to eventually overspread the Ohio Valley and Mid

Atlantic regions. A cold front initially draped from the central

Plains into the Lower Great Lakes will move generally southeastward

through the period, as one or more frontal waves traverse the front

from the mid MS Valley into the Northeast and Mid Atlantic. 



...Ohio Valley into parts of the Mid Atlantic...

A plume of relatively steep midlevel lapse rates will emanate out of

an anomalously hot and well-mixed regime across the Southwest and

central/southern Plains and overspread parts of the Ohio Valley on

Sunday. With favorable deep-layer flow/shear expected across the

Ohio Valley and Mid Atlantic, the primary uncertainty regarding the

magnitude of buoyancy and potential severe threat is low-level

moisture return. The partially modified nature of returning Gulf

moisture and a tendency for strong antecedent heating/mixing

upstream of the Ohio Valley may continue to result in less

aggressive moistening compared to most guidance. However, with

relatively cool midlevel temperatures (-14C to -16C at 500 mb), even

dewpoints in the low/mid 50s F will result in moderate buoyancy

(MLCAPE of 1000-1500 J/kg) where sufficient heating occurs. 



The greatest confidence in diurnal storm development currently

resides within the eastern portion of the primary buoyancy plume

across PA and eastern OH, where weaker capping and a modest

warm-advection regime could result in isolated to widely scattered

supercell development along/ahead of the front. Weaker ascent with

southwest extent reduces confidence in development across the lower

Ohio Valley, though isolated supercell development cannot be ruled

out in this region as well. An increase in storm coverage is

expected into Sunday night as the cold front begins to surge

southeastward, though much of the nocturnal activity may tend to be

anafrontal and somewhat elevated. 



Large hail (potentially to the size of golf balls or larger) could

accompany any longer-lived supercells during the afternoon and

evening. The environment will also be favorable for damaging-wind

potential, especially where stronger diurnal heating occurs, though

potential for organized clustering is uncertain due to the eventual

undercutting frontal passage. Also, while flow will remain rather

veered, low-level shear/SRH may be sufficient to support some

supercell tornado threat, conditional upon sufficient low-level

moistening. A corridor of greater tornado probabilities may

eventually be needed, if trends support more substantial moisture

return than currently expected.



..Dean.. 03/21/2026



$$