ACUS03 KWNS 200728

SWODY3

SPC AC 200727



Day 3 Convective Outlook  

NWS Storm Prediction Center Norman OK

0227 AM CDT Mon Apr 20 2026



Valid 221200Z - 231200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS

OF THE HIGH PLAINS OF NEBRASKA SOUTH INTO THE TEXAS PANHANDLE...



...SUMMARY...

Severe thunderstorms capable of hail and gusty winds may develop

during the late afternoon and evening across portions of the High

Plains. Elsewhere, thunderstorms will be possible across the

northern Gulf Coast and portions of the Ohio Valley.



... Synopsis ...



A shortwave trough will eject northeast out of the basal region of

the western CONUS trough and into the northern Plains on Wednesday.

As this happens, strengthening southerly/southwesterly midlevel flow

will overspread much of the High Plains. A surface cyclone over

eastern Montana will gradually deepen as it slowly moves east. 



... Central High Plains south into the southern High Plains ...



As the Montana surface cyclone gradually deepens on Wednesday, Gulf

moisture will be drawn northward into the central and northern

Plains. As the upper trough approaches the region during the late

afternoon/evening, modest height falls are expected to overspread a

sharpening dryline across far eastern Colorado or western Nebraska

south into the Texas Panhandle. Kinematic profiles up and down the

dryline show ample vertical shear for supercells capable of

producing hail and gusty winds. However, considerable uncertainty

remains regarding thunderstorm coverage owing to the significant

differences in the depth and quality of the boundary layer moisture

return noted in the 20260420/00Z guidance suite. For example, the

NAM is nearly 5F more moist along the dryline across portions of

Nebraska than global models. 



That said, pattern recognition and 00Z RRFS suggest that at least a

couple of storms should develop along the dryline from Nebraska

south into the eastern Texas Panhandle. Deep-layer flow will largely

parallel the dryline during the afternoon which should preclude much

eastward advancement. A 5% unconditional risk area has been added to

account for this potential.



... Elsewhere Across the CONUS ...



Thunderstorms may be ongoing at the start of the forecast period and

persist into the early afternoon across portions of the northern

Gulf Coast. The thunderstorm potential should wane with time as

increasing midlevel heights suppress large-scale ascent. 



Additionally, modest low-level moisture and weak instability may

support a few lightning strikes within a weak surface boundary

across the Ohio Valley.



..Marsh.. 04/20/2026



$$