Area Forecast Discussion
Issued by NWS Boise, ID
FXUS65 KBOI 271004
Area Forecast Discussion
National Weather Service Boise ID
404 AM MDT Mon Mar 27 2017
.SHORT TERM...Today through Tuesday...Widespread light to moderate
showers this morning as an upper level trough continues its
journey across the region. Showers will slowly taper off west to
east over the course of the day as the trough moves east.
Expecting a slight chance of thunderstorms with minimal
instability for a brief window of time this afternoon over most
areas, though not expecting any strikes over the Treasure Valley.
Breezy northwest winds will set in today, increasing this
afternoon, in the wake of the overnight frontal passage. Will see
gusts to about 30 to 35 mph across portions of southwest
Idaho...Mountain Home, south and east...diminishing around sunset.
A ridge begins to move into the region overnight and into Tuesday
for a 2-5 degree warmup and clearing skies.
Several rivers continue in minor flood, including the Boise in
Ada and Canyon counties and the Silvies in northern Harney County.
The Snake River near Weiser is temporarily below flood stage, but
is forecast to rise back into minor flood Monday afternoon.
Finally, flooding from snowmelt continues to impact the Camas
Prairie and surrounding areas.
.LONG TERM...Tuesday night through Sunday...Next system arrives late
Wednesday ahead of a deepening trough which will track across SW
Idaho and SE Oregon on Thursday. Warm southwest flow develops across
the area bringing above normal temperatures for Wednesday. An
impressive moisture field develops late Wednesday night with
widespread precipitation spreading across the region early Thursday
morning. Precipitation amounts are impressive with this system, as
the center of the upper level trough passes by overhead, with the
mountains receiving 1.0 to 1.5 inches of liquid equivalent. Snow
levels start out high, around 7500-8500 feet with the onset of
precipitation. About 3/4 of the precipitation will fall with the
high snow levels, before snow levels fall to around 4500 feet as
the heaviest precipitation pushes south and east on Friday
morning. Significant snow will fall on the peaks above 8000ft. As
the trough moves into southern Utah, windy conditions develop
across our region, and wrap around moisture could bring moderate
snow accumulations to the southwest highlands and southern Twin
Falls County on Friday. Ridging builds into the Pacific NW on
Friday, bringing cool north-northeasterly flow through Saturday.
Forecast confidence beyond Saturday is low.
.AVIATION...MVFR to IFR in rain and snow showers. Showers
decreasing in coverage this morning and becoming VFR with partial
clearing in the valleys. Mountains obscured. Scattered showers will
develop this afternoon across region with a slight chance of graupel
and thunder. Clearing after sunset. Snow levels around 4500-5000ft
MSL. Winds aloft at 10kft MSL: NW 20-30kt. Surface winds: light this
morning, becoming NW 10-20kt with gusts to 30kt near KMUO east to
Magic Valley near KJER/KTWF.