Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 192336 CCA

Area Forecast Discussion...CORRECTED
National Weather Service Boise ID
325 PM MST Sun Feb 19 2017

...corrected Hydrology section...

.SHORT TERM...Tonight through Tuesday...The upper wave that`s
supporting shower and thunderstorm development over the area this
afternoon will lift northeast overnight. Any thunderstorm threat
will dissipate by sunset and precipitation chances will decrease
across southern portions, to include the Snake River Plain, into
Monday morning. However, showers will continue across the east-
central Oregon and west-central Idaho mountains overnight, but to
a lesser coverage and intensity. Warm advection on southwest flow
ramps up on Monday bringing a resurgence of rain/snow to the area.
Given the more stable air mass mountains will be focus of heavier
precipitation, with shadowing possible in downwind valleys. Snow
levels will rise to between 6-7k feet for Monday afternoon into
Tuesday morning, dropping back to around 5k feet by Tuesday
afternoon. Expect breezy conditions across higher terrain on
Monday, but the windiest day will be Tuesday, as mid-level winds
(700 mb) push 50 kts over much of the area. With the stronger
winds and mixing, Tuesday will see the warmest temperatures,
especially at lower elevation sites.

.LONG TERM...Tuesday night through Sunday...Southwest flow aloft
Tuesday night with a deepening trough offshore. Snow levels start
Wednesday around 4000 feet MSL, but quickly drop to valley floors
by Wednesday afternoon. The majority of the precipitation and
moisture stays out of the valley during this time, but chances still
remain to see a few stray snow showers. With temperatures climbing
above freezing during the daytime, impactful accumulations are not
expected in the lower elevations. After Thursday a cold northerly
flow is in place aloft keeping the snow levels down at the valley
floors, however models continue to disagree on any feature coming
through the CWA. Kept the mention of precipitation chances in
through the extended period, but still not expecting any major
accumulations in the lower elevations. Temperatures stay below
normal during the period.


.AVIATION...Mostly VFR. IFR conditions possible Sunday within
heavier showers. Showers currently pushing in from the southwest and
will continue to press through this evening. Another batch of
precipitation moves in Monday afternoon. Surface winds, southwest 10-
20 kts with gusts within showers of 25-30 kts. Winds aloft to 10k
feet MSL, southwest 20-40 kts through Monday AM then increasing to
40-55 kts after 16z Monday.


.HYDROLOGY...Little change in expected hydrologic conditions
through Tuesday. Have issued flood watches for the Malheur and
Weiser Rivers as both are forecast to reach flood stage Tuesday
into Wednesday. These are based off current QPF and snowmelt
forecasts. As these inputs will likely change over the next 48
hours, so will the river forecasts. Also continued the ESFBOI
product highlighting the continued threat for lowland and small
stream flooding at low-elevations sites still holding a snowpack.





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