LIVE MAP (ABOVE) ... SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1247 AM CDT Sat May 20 2023
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM
SOUTH-CENTRAL OREGON INTO FAR EASTERN WA...NORTHERN ID...AND FAR
WESTERN MT...
...SUMMARY...
Isolated severe thunderstorms are are possible from south-central
Oregon into far eastern Washington, northern Idaho, and far western
Montana Sunday afternoon and evening.
...Synopsis...
The upper pattern across the CONUS will be characterized by
predominantly weak flow early Sunday morning, with ridging in place
over the western CONUS and broad cyclonic flow across much central
and eastern CONUS. The only exceptions to this weak flow will be
from the Great Lakes into ME, which will be along the southern
periphery of the troughing across eastern Canada, and over the
Pacific Northwest late in the period as a shortwave trough moves
through.
Surface pattern east of the Rockies will be dominated by high
pressure, the center of which is forecast to gradually drift
eastward from southern MO into the lower OH Valley. Dry air mass
associated with this high will limit the low-level moisture across
much of the central and eastern CONUS, confining the higher
dewpoints to the Southeast and central/southern TX.
Isolated thunderstorms are possible along and ahead of a weakening
cold front from eastern NC to FL. Afternoon thunderstorms are also
possible across the southern High Plains, as storms move eastward
off the higher terrain, supported by a convectively augmented
vorticity maximum moving within the larger scale upper ridging.
Modest shear and buoyancy is expected to limit the strength of any
storms that do develop.
...Interior Pacific Northwest into the Northern Rockies...
Somewhat greater severe potential is expected from the interior
Pacific Northwest into the northern Rockies. Here, a shortwave
trough is forecast to move into the region during the afternoon,
contributing to thunderstorm development as it interacts with the
diurnally destabilized air mass in place. Cold mid-level
temperatures will contribute to moderate buoyancy, with increasing
mid-level flow resulting in moderate shear as well. These
environmental conditions could result in a few stronger storms
capable of damaging gusts and/or hail.
..Mosier.. 05/20/2023
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