Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Sep 28 2023 17:08:06

ACUS02 KWNS 281708
SWODY2
SPC AC 281706

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1206 PM CDT Thu Sep 28 2023

Valid 291200Z - 301200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE NORTHERN PLAINS AND UPPER MS VALLEY...

....SUMMARY...
Scattered storms may produce hail or isolated severe gusts over
parts of the northern Plains and upper Mississippi Valley on Friday.

....Synopsis and Discussion...
Upper pattern early Friday morning is forecast to feature a weak low
over the upper OH Valley, ridging throughout the MS Valley, and
broad troughing west of the MS Valley ridging. Eastern upper low is
expected to gradually shift eastward, contributing to surface
cyclogenesis off the northern Mid-Atlantic coast. Upper ridging will
shift eastward, while a lead shortwave trough progresses through its
northwestern periphery across the Dakotas/southern Manitoba and
northern MN into far northwestern Ontario. A second shortwave will
likely move through the broad troughing from the northern Rockies
into Saskatchewan, while a third, more substantial shortwave moves
into northern/central CA.

High surface pressure will be in place over much of the eastern
CONUS, which, when combined with warm temperatures aloft, should
preclude thunderstorm development. The only exception is within the
warm-air advection zone north of the developing surface low over the
coastal northern Mid-Atlantic states. Here, showers and isolated
thunderstorms are possible throughout the day.

Farther west, elevated thunderstorms are expected early Friday
morning from the eastern Dakotas into MN, forced by a combination of
warm-air advection and large-scale ascent attendant to the shortwave
trough progressing through the region. Strengthening mid-level flow
ahead of this shortwave, combined with cold temperatures aloft, may
support hail with the strongest storms.

Outflow and cloud cover associated with the early-day precipitation
will likely sharpen the frontal boundaries in the vicinity of a
modest surface low over the Mid MO Valley. There is some potential
for air mass destabilization near this low and associated boundaries
as the boundary layer heats, but a prevailing warm layer around
700mb and lack of large-scale ascent casts some uncertainty to
whether deep convection can be sustained. However, moderate buoyancy
and steep low-level lapse rates suggest there is a conditional risk
for strong downbursts and large hail.

...Mosier.. 09/28/2023

$$

= = =
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.14-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

.