314
FXUS65 KBOI 271607
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1007 AM MDT Sat Apr 27 2024

.DISCUSSION...Southwest ID and southeast OR remains between two
systems this morning, one extending from northern and eastern
ID to UT and one over western OR and WA. Expect mostly sunny
skies this morning, with scattered showers developing over the
central ID mountains this afternoon, with the heating of the
day. Clearing overnight with patchy fog in the mountain valleys,
then similar conditions on Sunday. Breezy west to northwest
winds expected during this afternoon and Sunday afternoon, with
gusts up to 35-40 mph in the Magic Valley. No updates.

&&

.AVIATION...Generally VFR, but partly cloudy with some mid-level
ceilings. Scattered showers over Central Idaho develop this
afternoon, primarily over high terrain. Snow levels 6000-7000 ft
MSL. Surface winds: W to NW 10-20 kt with gusts to 20-30 kt in the
Snake River Valley. Winds aloft at 10kft MSL: W to NW 10-20 kt.

KBOI...VFR with scattered mid-high clouds. Surface winds: NW 10-20
kt, with gusts to 20-25 kt through the afternoon.

Sunday Outlook...Mostly dry and VFR. Surface winds generally SW to
NW 5-15 kt, then variable 5-10 kt after sunset. Afternoon gusts to
20-30 kt around KMUO/KTWF/KJER.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Monday night...An area of showers
associated with a mid-level circulation/deformation zone in
eastern Idaho is near the eastern fringe of our forecast area
early this morning. The western edge of the showers is near
Jerome and Gooding and is expected to slowly shift eastward,
exiting east of the area by mid-morning. A weak upper trough to
our west is expected to reach SW Idaho this afternoon. Scattered
to numerous showers develop with the trough in central Idaho
while remaining dry across SE Oregon and the remainder of SW
Idaho. A weak surface low in central Idaho will enhance the
pressure gradient for windy conditions in southern Idaho from
Mountain Home to Twin Falls. There is a 20-60 percent chance of
showers in the West Central Mountains (mainly east of McCall)
tonight as another weak upper trough moves through northern
Idaho. West-southwest flow aloft will bring drier conditions on
Sunday, although it will be breezy across most SE Oregon and SW
Idaho. Little change in temperatures are expected over the
weekend, averaging within a couple degrees of normal.

A strong and fast-moving cold front is anticipated to move
through on Monday. Windy conditions develop by the afternoon,
and it could be very windy across s-central Idaho - including
the Camas Prairie, Upper Treasure Valley, and Western Magic
Valley where a Wind Advisory may eventually be warranted. An
upper trough lags behind the front, bringing a chance of
showers to mainly the higher elevations. Snow levels fall to
around 4000-5000 feet and there may be snowfall accumulations in
the higher elevations of Baker County and central Idaho.
Preliminary totals of 1 to 3 inches are possible, with locally
higher amounts north of McCall. Much cooler temperatures (5-10
degrees lower) arrive with the cold front. The winds and
showers diminish Monday night.

LONG TERM...Tuesday through Saturday...An upper level low will
deepen over the Pacific Northwest on Tuesday, bringing slightly
below normal temperatures to the region and a slight chance of
precipitation to the region. For Tuesday into Wednesday, there`s
a low chance of precipitation in the valleys (10-20% chance)
with much higher confidence in precipitation over higher terrain
in Baker County-West Central Mountains (50-60% chance). Snow
levels will drop to 3500-4500 feet across the area by Tuesday
evening-Wednesday morning, so some precipitation over the
mountains will briefly fall as snow. Minor accumulations are
anticipated, with areas below about 7000 feet seeing less than
an inch. The surface and upper level pressure gradient will
tighten as the low digs into the region, bringing gusty westerly
winds to the region on Tuesday and Wednesday, especially in the
Snake River Valley. The low will then move to the east by late
Wednesday, as northwest upper level flow returns for Thursday
and a ridge looks to build in over the region on Friday. This
northwest flow will bring dry conditions and slightly warmer
temperatures as a warmer and drier air mass looks to creep in
from the southwest.

Model agreement remains high through Thursday, but differences
exist in the storm track by early Friday. Some deterministic and
cluster solutions show a shortwave trough moving through the
region by the end of the week, while others show a ridge
building in. This brings a wide spread to the potential
temperatures and precipitation for the region on Friday and
Saturday. The NBM favors higher temperatures than most of the
individual forecast models on the Wednesday-Friday period, so
have lowered these temperatures in the extended slightly to
reflect the higher probability for lower temperatures.

&&

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

&&

$$

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DISCUSSION...KA
AVIATION.....JM
SHORT TERM...BW
LONG TERM....SA