174
ACUS02 KWNS 040541
SWODY2
SPC AC 040540

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Sat May 04 2024

Valid 051200Z - 061200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS INTO THE ARKLATEX AND LOWER MISSISSIPPI
VALLEY...AND PORTIONS OF OHIO INTO WESTERN PENNSYLVANIA...

...SUMMARY...
Isolated strong to severe thunderstorms may occur Sunday across
parts of the southern Plains into the ArkLaTex and lower Mississippi
Valley, and separately over portions of Ohio into western
Pennsylvania.

...Synopsis...
A pronounced/deep closed upper low over CA/NV will move eastward
over the western states on Sunday, eventually transitioning into an
open wave as it overspreads the northern/central Rockies by early
Monday morning. A weak southern-stream shortwave trough is forecast
to move northeastward from the southern Plains to the ArkLaTex and
lower MS Valley through the day. Another upper trough over Ontario
is expected to advance into Quebec, with the southern portion of
this feature glancing the lower Great Lakes and vicinity. Surface
lee cyclogenesis will occur across the northern High Plains ahead of
the western CONUS upper trough/low. Rich low-level moisture should
advance northward across the southern/central Plains through the
period, although convection over TX may temporarily slow this
process.

...Southern Plains into the ArkLaTex/Lower Mississippi Valley...
Multiple thunderstorm clusters will probably be ongoing across parts
of west into central TX at the start of the period Sunday morning.
An isolated threat for damaging winds and hail may persist with this
activity as it spreads eastward towards the middle/upper TX Coast
through early Sunday afternoon. A gradual uptick in convective
coverage and intensity may occur as modest destabilization occurs
ahead of ongoing thunderstorms. Strong deep-layer shear should
support continued convective organization, with small bowing
clusters possible. Isolated strong to severe thunderstorms may also
occur across parts of the ArkLaTex into the lower MS Valley as a
weak shortwave trough moves across these regions through Sunday
afternoon. However, effective bulk shear should remain weaker over
these areas. Based on the likelihood and probable placement of
morning convection across central TX, have expanded the Marginal
Risk a bit southward/eastward, while also trimming much of north TX
and south-central OK out of severe probabilities.

...Ohio into Western Pennsylvania...
Modest destabilization should occur ahead of a weak front advancing
east-southeastward across the OH Valley on Sunday. Isolated to
scattered thunderstorms should develop by Sunday afternoon along or
just ahead of this boundary, as weak large-scale ascent associated
with an upper trough over Ontario/Quebec overspreads this region.
Deep-layer shear of 20-30 kt should support marginal updraft
organization. Occasional strong to damaging winds may occur with any
small clusters that can consolidate and spread east-southeastward
across parts of OH into western PA and vicinity Sunday afternoon and
early evening. This activity should gradually weaken through the
evening across PA as it encounters a less unstable airmass.

...Northern High Plains...
Low-level moisture is expected to remain very shallow/meager across
the northern High Plains through the period. Even so, daytime
heating and steep mid-level lapse rates may still support weak
instability developing through Sunday afternoon along/east of the
sharpening surface lee trough. While isolated high-based convection
that develops across this region could produce locally strong/gusty
winds, the overall severe threat appears too limited to include low
severe probabilities at this time.

..Gleason.. 05/04/2024

$$