Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 250259

Area Forecast Discussion
National Weather Service Boise ID
859 PM MDT Mon Apr 24 2017

.DISCUSSION...Upper wave is digging into central Oregon this
evening with widespread showers and isolated thunderstorms
continuing out ahead of it. Shower coverage decreases across
southeast Oregon after midnight, while continuing across southwest
Idaho, though to a lesser extent in the Snake Plain. With less
activity expected in the valley, have made changes to lower
precip amounts for the rest of tonight. Otherwise current
forecast is on track.


.AVIATION...VFR & MVFR with showers continuing through 25/12Z.
Mostly dry and clearer on Tuesday, except a few showers in the Idaho
Central Mountains in the afternoon. More widespread showers after
26/06Z. Surface winds: generally west/northwest 10-20 kts with gusts
20-30 kts on Tuesday afternoon in the Magic Valley. Winds aloft near
10KFT MSL: Northwest 20-30 kts, then after 25/12Z to 10-15 kts, then
after 25/18Z turning west at 10-20 kts.


SHORT TERM...Tonight through Wednesday...Upper level trough is
centered near Portland, OR and is moving southeast this
afternoon. Numerous showers and a slight chance of thunderstorms
will continue through this afternoon. Storm total precipitation
amounts of 0.75 to 1.25 in of water equivalent is expected through
Tuesday morning in the mountains with snow levels near 6000 ft,
lowering to 4500 ft Tuesday morning. Lesser precipitation amounts
of 0.15 to 0.50 in for the valleys. The center of the shortwave
is expected to track across SE Oregon tonight into northern Nevada
by Tuesday morning. Wrap around moisture will keep precipitation
going across the Idaho zones through Tuesday morning and in the
Boise mountains through midday Tuesday as the system pushes
southeast. Drier air will move into the region for Tuesday with
slightly warmer temperatures. A potent system arrives on
Wednesday, with an impressive fetch of moisture. Expect
precipitation to become widespread, much like today across SE
Oregon and SW Idaho on Wednesday afternoon. Precipitation amounts
of upwards of an inch in the mountains and a half inch in the
valleys, and possibly more, is expected with this system. Snow
levels range from 5500 ft in the central ID mountains to near
7500 ft near the NV border.

LONG TERM...Wednesday night through Monday...Wednesday`s storm
moves off to the east Wednesday night followed by colder but still
moist northwesterly flow aloft Thursday. Thursday and Friday look
abnormally cold with an upper low over the northern Rockies that
will dig south into Utah and Colorado by Friday. 850-700 mb
thickness gets low enough to support wet snow or mixed rain and
snow down to the lowest valleys both Thursday and Friday mornings,
with Thursday the colder day by a slight margin. However, qpf
will be slight and no snow accumulation is expected. Warming and
drying later Friday through Monday with temps rising to almost
normal by Monday as a short wave ridge aloft comes in from the





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