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000
FXUS65 KBOI 141522
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
922 AM MDT Sun Apr 14 2024

.DISCUSSION...Multicellular thunderstorms have been
continuously pulsing up and down this morning just north and
west of the Steens Mountains in southeast Oregon. Due to this
earlier than anticipated activity, and hi-res models`
increasing coverage of shower and thunderstorms, the forecast
has been updated to increase chances of precipitation over the
Treasure Valley and Boise Mountains this afternoon. Outflow
winds are the main concern with this activity, with localized
gusts up to 40-50 mph possible near stronger storms. Otherwise,
the low seems to be on track to move into central Nevada later
today, bringing cooler temperatures, high elevation snow, and
breezy westerly winds.

&&

.AVIATION...Mostly VFR. Scattered showers and isolated thunderstorms
in far SE Oregon (south of KBNO) this morning. Scattered showers and
isolated thunderstorms across SE Oregon and mainly the higher
terrain of SW Idaho this afternoon. Outflow wind gusts to 25-35 kt
near storms. Activity reaching KBNO, KBKE, KMYL, and possibly
KONO/KEUL/KBOI. Mountain obscuration with MVFR conditions in showers
and storms. Snow levels 6000 near the Nevada border and 7500 ft MSL
KBKE-KMYL. Surface winds: variable 5-10 kt, becoming SW-SE 10-20 kt
with gusts up to 25-30 kt after Sun/16Z. Winds aloft at 10kft MSL:
SE-E 15-30 kt.

KBOI...VFR. Mid level clouds increasing this afternoon. Isolated
showers Sun/20Z until Mon/00Z, with potential for a stray lighting
strike. Will need to monitor for erratic outflow wind gusts around
25-35 kt from nearby storm activity. Outside of storm outflows: S to
SE surface winds 10-20 kt, becoming S to SW this afternoon, then
shifting to NW 5-10 kt around sunset.


&&

.PREV DISCUSSION...
SHORT TERM...Today through Tuesday night...This morning,
satellite imagery reveals a significant low pressure system
positioned just off the coast of San Francisco. Notably, there
are now two distinct low centers identifiable, with one moving
northeastward, situated south of San Francisco, while the other
is located near 125 W and 35 N, heading southeastward. The
northeastern-moving low center is anticipated to be the primary
influencer of today`s weather, expected to traverse north-
central Nevada by this afternoon.

Early this morning, radar observations indicate ongoing
thunderstorm activity west of Burns, within Harney County,
showcasing ample moisture and dynamics in the region. This
thunderstorm activity is projected to persist throughout the
morning and into the afternoon, particularly as the approaching
low center intensifies buoyancy and forcing. Surface heating,
notably across southeast Oregon, will further enhance
instability, further fostering thunderstorm development.
Additionally, thunderstorms are forecasted to emerge over the
West Central and Boise mountains, although moisture availability
is comparatively lower across southwest Idaho. The prevailing
dry boundary layer, particularly evident in the valley, is
anticipated to restrict precipitation amounts and foster gusty
outflow winds. In southeast Oregon, rain- induced cold pools may
prompt outflow wind gusts of up to 35 knots in the lower
valleys. Despite a decrease in temperatures by about 15 degrees
compared to yesterday, today`s temperatures are expected to
remain approximately 5 degrees above normal.

Showers and thunderstorms are forecasted to persist into late
evening across Harney County and the West Central Mountains. By
Monday, the low centers are projected to consolidate into a
single low pressure system over Utah, consequently intensifying
the surface pressure gradient across the forecast area, leading
to gusty northwest winds. The strongest winds are expected to
impact the lower valleys, spanning from Baker City through the
Western Magic Valley. Probabilistic data suggests a 50% chance
of wind gusts exceeding 48 knots from Mountain Home through the
Western Magic Valley by Monday afternoon. Ongoing trends in
guidance may necessitate wind advisories for Monday afternoon.

The pressure gradient is forecasted to remain tight overnight
and into Tuesday, coinciding with the approach of a cold core
low pressure system accompanied by a robust cold front from the
north. While the timing of the frontal passage remains somewhat
inconsistent among models, most guidance indicates the frontal
passage occurring between Tuesday afternoon and early Wednesday.
However, moisture along the front is limited, with only a
slight chance of snow showers expected in the West Central
Mountains. Tuesday`s temperatures are anticipated to drop to
approximately 5 degrees below normal. Wind advisories may also
be warranted on Tuesday, particularly across the Western Magic
Valley.

LONG TERM...Wednesday through Sunday...Some of the latest
model guidance brings the track of a large Canadian trough
farther west than previous runs, as it moves into the
Northwestern U.S. This change has decreased our confidence in
the temperature forecast on Wednesday, but the forecast has now
trended several degrees cooler as a result. Northwest winds
should remain breezy area-wide, but shower activity is currently
still limited to central Idaho (15-30% chance) on Wednesday
into Thursday. Confidence in snow level is also affected, but
levels should remain as low as 3000-4500 feet MSL in the area of
precipitation. As the trough exits to the east, weak high
pressure will bring a warming and drying trend to the area
Thursday through the weekend. Temperatures are expected to rise
to 10 degrees above normal by the weekend.

&&

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

&&

$$

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DISCUSSION...SA
AVIATION.....BW
SHORT TERM...JDS
LONG TERM....SH