Area Forecast Discussion
Issued by NWS Boise, ID

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000
FXUS65 KBOI 251530
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
930 AM MDT Tue Apr 25 2017

.DISCUSSION...Mostly sunny day today in the wake of a shortwave
passage earlier this morning. Breezy surface winds mainly east of
Mountain Home will diminish this afternoon. Next moist upper
level trough and cold front are quickly approaching the Pacific
Northwest coast today. Clouds associated with this system will
reach Southeast Oregon early this afternoon. The cold front with
showers will reach Southeast Oregon around 03z tonight and moves
east into Southwest Idaho late tonight/early Wednesday morning.
Wednesday still looks to be very wet with the bulk of moisture
moving over the Intermountain West. Updated POPs, QPF and WX for
tonight through Wednesday morning. Update will be out shortly.

&&

.AVIATION...Widespread VFR with scattered-broken mid and high level
clouds. Isolated IFR ceilings in the West Central Mountains
(including KMYL) will improve to VFR by 18Z. Scattered MVFR showers
will continue in the West Central and Boise Mountains through this
afternoon. Surface winds: west-northwest 5-15 kts, except 15-25 kts
from a KMUO to KJER/KTWF corridor. Winds aloft near 10k ft MSL: west-
northwest 10-20 kts.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Wednesday...Showers continue to move
through the central Idaho this morning. Satellite is demonstrating
drier air, associated with a diving shortwave, moving into
eastern Oregon which will help to keep shower activity minimal
through the afternoon. A few showers across the West- Central and
Boise Mountains. Clearing expected with the drier air, allowing
temperatures to warm slightly. The moisture reprieve will be
brief, with the next Pacific system moving inland and into eastern
Oregon by late Tuesday evening. A stronger secondary push of
moisture will move inland after midnight, creating widespread
showers by early Wednesday morning. Models in good agreement that the
upcoming system will be rather potent in regards to moisture with
around a half inch possible in the valleys and close to 1 inch in
the mountains by Wednesday evening. Snow levels remain between
5000 and 6000 ft MSL, keeping snow and a rain-snow mix possible
through Wednesday. Colder temperatures expected due to the passage
of a cold front. Additionally, passage of this front will aid in
creating instability around the OR/ID border, with some
thunderstorms possible. Showers and thunderstorms will then
continue through Wednesday afternoon.

LONG TERM...Wednesday night through Monday...As Wednesday`s
system exits the region, continued moisture within a northwesterly
flow aloft will prevail, though the focus of precipitation will
generally be over the higher terrain. Thicknesses drop across the
region Thursday and into Friday for temperatures 10-15 degrees below
normal and a slight chance of morning snow down to valley floors.
QPF amounts will be low however, and no accumulation is expected. A
shortwave ridge will push into the region late Friday, bringing a
brief period of drying and warming conditions through late Sunday
before the ridge breaks down and a moist northwest flow aloft sets
in once again. Temperatures will be within 5-10 degrees of normal
beginning Saturday through the end of the period with low 60s
expected across the Snake River Plain over the weekend.


&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

$$

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DISCUSSION...JDS
AVIATION.....BW
PREV SHORT TERM...KB
PREV LONG TERM....AB



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