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000
FXUS65 KBOI 252029
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
229 PM MDT Thu Apr 25 2024

.SHORT TERM...Tonight through Saturday night...A shortwave
trough pushing in from the coast will advance a line of showers
and isolated thunderstorms as it moves through the region
overnight. For now have limited the mention of thunder to SE
Oregon zones as later timing is less favorable east of the ID/OR
border. Gusty outflow winds of up to 40 mph will accompany the
line of precipitation. The upper trough slows its eastward
movement on Friday as energy closes off over the Great Basin.
Daytime instability will feed shower and thunderstorm
development mostly over higher terrain. The cold air aloft could
support graupel or small hail on strong cells with wind gust
potential to 35 mph. For the bulk of the precipitation snow
levels will be above 6kft MSL which will limit accumulation to
the higher peaks. Through Saturday morning snow totals of 2 to 4
inches are expected above 6500 feet in the w-central Idaho mtns
and eastern Boise mtns. Much of the area dries out on Saturday
while moisture wrapping around the exiting trough keeps a 20-40%
chance of showers over w-central Idaho through the afternoon.
The dry westerly flow continues into Saturday night with any
small chance of showers (15-25%) limited to northern Valley
County. Temperatures are near normal through Saturday.

.LONG TERM...Sunday through Thursday...Models are in excellent
agreement starting the long term off with WNW flow aloft Sunday,
becoming zonal Monday into Tuesday. This will bring in a chance
(10-30%) of showers mainly in the northern mountains and along
the ID/NV border on these days. The first notable disagreement
in the latest deterministic runs arrives Wed, as the EC depicts
a strong upper low moving across northern ID while the GFS shows
dry zonal flow. Comparing these to the available ensemble runs
shows that the EC is an outlier (15% of the spread). Therefore,
the forecast favors the drier GFS, but still holds on to a
chance (still 10-30%) of showers mainly in the northern
mountains. Models remain out of synch with each other into Thu,
but there is general agreement that another upper low will
approach the Pacific Coast Thu. This is likely to bring cooler
and wetter weather late next week and into next weekend.
Overall, temps will be near normal Sun-Tue, then above normal
Wed and Thu, with Wed the warmest day next week.

&&

.AVIATION...Generally VFR, then areas of MVFR moving into eastern
Oregon this afternoon as showers/weak thunderstorms develop. This
area will move into southwest Idaho this evening. Surface winds: W
to NW 5-15 kt. Gusts to 30 kt in stronger showers, and along/just
behind the cold front tonight. Winds aloft at 10kft MSL: W-NW 15-25
kt.

KBOI...VFR under mid to high level clouds today. Surface winds: NW 5-
15 kt, with gusts near 20 kt this afternoon. A cold front will
arrive this evening with light rain showers along and behind the
front. The front will also lower ceilings to 5000-7000 ft AGL and
bring brief wind gusts to 30 kt. Thunderstorm chances less than 15%
tonight.

Weekend Outlook...Scattered to numerous showers and isolated
thunderstorms will continue into Friday, with the highest coverage
in the mountains. Periods of MVFR conditions and mountain
obscuration in showers. Snow levels 5500-6500 ft MSL. Scattered
showers will continue into Saturday and Sunday over the mountains,
with mostly dry conditions and decreasing clouds elsewhere. Surface
winds generally W-NW 10-25 kt, with the strongest winds Friday night
and Saturday from KMUO east through the Magic Valley where gusts up
to 40 kt will develop.

&&

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

&&

$$

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SHORT TERM...DG
LONG TERM....SP
AVIATION.....SP