Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 260321

Area Forecast Discussion
National Weather Service Boise ID
921 PM MDT Tue Apr 25 2017

.DISCUSSION...Leading edge of moist storm system is pushing into
the interior NW this evening. Bulk of precipitation is still
timed to make its way into southeast Oregon and southwest Idaho on
Wednesday. For tonight, a chance of light showers exists with
passage of a weak warm front. Exception is the Western Magic
Valley which remains dry until the main push of moisture arrives
later Wednesday morning. Have made minor updates to dry out
Western Magic Valley for tonight, otherwise forecast is on track.


.AVIATION...Showers increasing and ceilings lowering. Snow levels
5500-6500 ft. Showers tapering off after 27/06Z. Surface winds:
generally 12 kts or less. Winds aloft near 10 KFT MSL: West 20-30


SHORT TERM...Tonight through Thursday...Pacific moisture
associated with a cold front ahead just reached the Oregon coast
at 20z. Showers have developed head of the front which will move
into Southeast Oregon early this evening and Southwest Idaho early
Wednesday morning. The main push of precipitation will come post
frontal passage late Wednesday morning when the upper level low
dynamics moves over the region. The heaviest precipitation will
fall across Southeast Oregon Wednesday morning and south of the
Western Snake River Plain Wednesday afternoon. In general, the
valleys will see about three tenths of inch of rain with the
mountains below 6000 feet seeing closer to three quarters of inch
of rain on Wednesday. Cold northwesterly flow develops on Thursday
for continued showers and breezy conditions. Temperatures fall to
around 15 degrees below normal on Thursday.

LONG TERM...Thursday night through Tuesday...Pattern changes little
through early next week as a longwave upper ridge remains off the
west coast and a northwest flow aloft prevails over our area. A
departing trough will continue to support showers on Friday,
followed by a weak ridge and drier weather on Saturday. Moisture
residing within the northwest flow aloft will bring a chance of
showers Sunday through Tuesday, favoring the northern mountains.
Temperatures will be 5-10 degrees below normal.





PREV LONG TERM....BW/DD is the U.S. government's official web portal to all federal, state and local government web resources and services.