196
FXUS65 KBOI 222128
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
228 PM MST Fri Nov 22 2024

.SHORT TERM...Tonight through Sunday night...At 2 PM MST radar
sees only scattered light rain showers in the Boise Mountains.
The rest of our CWA is cloudy, breezy, and mild, except very
windy at higher elevations in southern Harney County. Winds
will decrease there this evening. Cold front is breaking up in
eastern Oregon but the portion in ne California should redevelop
tonight as a vort center in the Pacific near 40/130 approaches.
A new warm front is expected to form in southeast Oregon later
tonight and move northeastward through our CWA overnight and
Saturday morning, followed by the cold front moving eastward
later Saturday. Instability near the cold front looks strong
enough for a slight chance of thunderstorms on the Idaho side
Saturday afternoon. Models continue to show moderate to heavy
pcpn (1-2 inches total liquid equivalent) tonight through
Saturday in eastern Oregon and west central Idaho. Snow level
will stay above 6000 feet MSL until Saturday morning so most
pcpn will be rain. Rivers will rise but not to flood stage.
Rain will change to snow down to 5000 feet Saturday afternoon
behind the cold front, then 4000 feet Saturday evening, and
down to valley floors Sunday morning when pcpn is nearly over.
Total snowfall will be 12-18 inches where pcpn stays all snow,
but only a couple inches near the 5000 foot level. Most of the
cold air has been mixed out of the lower valleys so we don`t
expect a surprise snowfall at low elevations as occurred with
the last storm.  Rain and snow showers will continue Sunday
on the Idaho side as the upper trough moves inland and through
the area. Brief upper ridging will pass through late Sunday
followed by another Pacific trough and chance of light snow in
eastern Oregon Sunday night. Temperatures will continue to
slowly lower through Sunday night but only to near normal for
late November.

.LONG TERM...Monday through Friday...Ensembles are in excellent
agreement that an upper low centered off the coast of Oregon
Monday morning will move east and open up Tuesday, then move
through our area Tuesday night. This will keep relatively high
chances of precipitation (30-80%) going through the early part
of the long term period. Models remain in above-normal agreement
on the flow all the way through Friday, so this is a high-
confidence long term forecast. As the trough moves east
Wednesday, fairly dry air will move into the area on NW flow
aloft. This will lower our chance of precipitation to just a
slight chance 10-25%) in the higher terrain Wed through Friday.
Temps will start the week a few degrees above normal, but then
fall to near normal Tuesday and remain a few degrees below
normal through the end of the period. Thanksgiving Day is
expected to be dry and cool with light winds and partly cloudy
skies.

&&

.AVIATION...Mostly VFR. Widespread rain/snow creating MVFR/IFR
at times, especially in the mountains. Mountain obscuration.
Snow levels 7000-8000 feet tonight, lowering to 4000-6000 ft
Saturday. Surface winds: SW to SE 5-15 kt, except 15-25 kt with
gusts to 40 kt south of KBNO. Winds aloft at 10kft MSL: SW 40-60
kt, decreasing to 30-50 kt by 23/06Z.

KBOI...Mainly VFR, with periods of rain after 23/02Z. MVFR
ceilings possible in heavier rain. Surface winds: SE 12-18 kt
with gusts to 25 kt, decreasing this evening to ESE 8-12 kt.

Weekend Outlook...Mountains obscured. Cold front will move
through Sat, bringing widespread rain/snow and MVFR to LIFR
conditions at times. Snow levels falling to 4500-5500 ft MSL
late Saturday and 3000-4000 Sunday. Surface winds becoming
SW-NW 5-15 kt.

&&

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

&&

$$

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SHORT TERM...LC
LONG TERM....SP
AVIATION.....SP