Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 260956
Area Forecast Discussion
National Weather Service Boise ID
356 AM MDT Sun Mar 26 2017
.SHORT TERM...Today through Monday...A broad trough of low
pressure is poised to move ashore in the Pacific Northwest today.
The leading edge of the trough and associated moisture and cloud
cover is currently moving overhead in western Washington. No
shower activity is present across much of the interior Pacific
Northwest, however, coastal radars are indicating precipitation is
not far off-shore.
The trough is expected to move into Washington and Oregon today,
and across Idaho overnight and into Sunday. A warm front
associated with the trough will push south to north across the
area today with precipitation favoring northern locations and
higher terrain. Significant precipitation is anticipated when the
systems cold front moves through late today and overnight.
Forecast models are in good agreement that a consolidated band of
precipitation will accompany the cold front, along with dropping
snow levels. Valley locations will generally see between 0.15 and
0.25 inches of precipitation, while mountain locations will see
between 0.33 and 0.75 inches. Snow levels will start out around
6000 feet and drop closer to 5000 feet by early Monday. This will
allow for more whitening of the higher terrain of both SE Oregon
and SW and Central Idaho. Gusty northwest winds are anticipated
behind the front for much of the day Monday. Temperatures will
generally be at to slightly above normal today, then slightly
below normal on Monday.
.LONG TERM...Monday night through Saturday...A ridge will transition
across the area on Tuesday, with dry conditions. On Wednesday, a
trough begins to dig along the Pacific NW coast, setting up
southwest flow over eastern Oregon and SW Idaho. As this system
approaches, warmer southwest flow develops bringing in warmer air on
Wednesday. An impressive moisture field develops late Wednesday
night with widespread precipitation across the region. Precipitation
amounts are healthy with this system, as the center of the trough
passes by overhead, with the mountains receiving 1.0 to 1.5 inches
of liquid equivalent. Although snow levels start out at 7000-7500ft
with the onset of precipitation, snow levels begin to fall to around
5000ft midday on Thursday. Significant snow will fall on the peaks
above 8000ft. Ridging builds into the Pacific NW on Friday, bringing
cool north-northeasterly flow through Saturday. Temperatures will
generally be below normal through the extended period, with the
exception of Wednesday.
.AVIATION...Generally VFR. Increasing clouds. Showers will
spread into eastern Oregon midday today, and then into Idaho this
evening. Ceilings will then lower to MVFR-IFR as the cold front
moves through late Sunday night into Monday morning. Surface winds
SW to SE 5-15kt, gusts to 25kt in SE Oregon during the afternoon.
Winds aloft SW 25-35kt becoming Westerly 15-25kt by 03z/Mon.