ACUS01 KWNS 181234
SPC AC 181233
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0633 AM CST Thu Jan 18 2018
Valid 181300Z - 191200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
A few thunderstorms will occur over the Pacific Northwest today.
Some of the storms could produce small hail and gusty winds, but
should remain below severe criteria.
...Pacific Northwest Region...
Synoptic trough over the eastern Pacific will continue inland today
accompanied by a series of impulses north of cyclonic upper jet.
Cold air aloft associated with this feature will contribute to
steepening lapse rates and a corridor of weak instability over
coastal areas. This environment will support scattered showers and
thunderstorms today into tonight. Given cold temperature profiles
aloft and steep lapse rates (850-500 mb values to 7.5 C/km), a few
instances of small hail could occur. While 40-50 kt southwest winds
in the near-surface to 700 mb layer will persist through the first
half of the day, a gradual decrease is expected this afternoon as
cutoff low near British Columbia weakens. Gradient winds outside of
convection will be gusty at times. However, downward transport of
momentum could be further enhanced within the convective downdraft
cores, especially if any boundary-layer destabilization occurs.