From Mike Powell@618:250/1 to All on Sat Apr 13 09:33:00 2024
ACUS01 KWNS 131231
SWODY1
SPC AC 131230
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Sat Apr 13 2024
Valid 131300Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
OREGON...
...SUMMARY...
Thunderstorms with isolated severe hail and strong wind gusts will
be possible this afternoon and early evening across parts of Oregon.
...Oregon...
An upper low off the coast of northern CA this morning will move
slowly east-southeastward today towards central CA. South-
southeasterly low/mid-level flow on the northeast side of this
cyclone will help advect modest mid-level moisture and steep lapse
rates over OR through this afternoon. With daytime heating, around
500-1000 J/kg of MLCAPE should develop. Thunderstorms that initially
form over the higher terrain of central OR around 20-22Z should have
some organization, with 30-40 kt of deep-layer shear supporting a
mix of multicells and perhaps a marginal supercell or two. Isolated
severe hail may occur with the more discrete convection. Occasional strong/gusty winds also appear possible given steep low-level lapse
rates and a well-mixed boundary layer (inverted-v type soundings).
These thunderstorms should spread north-northwestward through the
early evening before gradually weakening with the loss of daytime
heating.
...Great Lakes...
Isolated thunderstorms may develop this evening and overnight across
the Great Lakes region as a weak mid-level shortwave impulse
embedded with a northwest flow regime moves southeastward. This
activity will likely remain elevated on the northeast periphery of
capping associated with an EML extending across much of the Plains
and Upper Midwest. Weak MUCAPE is generally expected where
convection should occur, which should keep the overall severe threat
low. Still, some small hail may occur given the presence of steep
mid-level lapse rates and strong deep-layer shear in the
cloud-bearing layer.