503
FXUS65 KBOI 280257
AFDBOI
Area Forecast Discussion
National Weather Service Boise ID
857 PM MDT Sun Apr 27 2025
.DISCUSSION...Precipitation development this evening remains
focused along a boundary near the ID/OR border. We`ve seen
showers and thunderstorms produce light to moderate rain this
evening with the highest amounts reported in the Boise
Mountains where 0.50-0.75" has fallen. This area precipitation
will continue through late evening, then gradually weaken as it
shifts east early Monday morning. While the thunderstorm threat
is likely over for most, can`t rule out a strike/flash or two
through midnight. Gusty NW winds will hold on over SE Oregon
overnight, diminishing towards sunrise before ramping up again
on Monday. No updates to the current forecast for this evening.
&&
.AVIATION...Showers and thunderstorm coverage decreasing into
the overnight hours as existing showers move south into NV.
Ceilings early Monday morning in West-Central Mountains valleys
should stay in MVFR, however small chance (10%) of IFR
conditions. Mountains obscured through Monday morning. Ceilings
in Western Magic Valley stay at most MVFR early Monday morning,
with small chance (10%) of IFR at KTWF, and larger chance (30%)
of IFR at KJER. Surface winds: N-NW 10-20 kt. Gusts in SE OR
early morning Monday 15-25 kt decreasing into morning hours.
Gusts in SW ID 15-25 kt beginning in the morning. Winds aloft at
10kft: Mostly N-NW 15-30 kt this afternoon.
KBOI...VFR. Showers decreasing overnight. Ceilings below 6000`
through 0900 UTC. Variable winds as precip moves out becoming NW
10 kt. Winds late morning into afternoon NW at 10-15 gusting
20 kt.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Tuesday night...At 2 PM MDT
showers were increasing in the southern 2/3 of our CWA, with
thunderstorms in Owyhee County, and beginning to form in the
Upper Weiser River Valley. Showers were moving westward in
Idaho and southwestward in Oregon around an upper low
centered in northern Utah. Meanwhile, a cold front was
forming in western Idaho and acquiring moisture from the
east. Latest models have increased QPF along the frontal band
as it moves slowly eastward this afternoon and evening.
Instability should develop more thunderstorms along the front
late today and early evening, with heavy rain the main concern.
To the west of the front, in Oregon, showers will be much
lighter. Total rainfall, just for tonight, will be .20 to
50 inch near the frontal band, with .10 to .20 inch elsewhere
in Idaho. Eastern Oregon will have less than .05 inch, except
up to .30 inch near the Idaho border. But eastern Oregon will
also be our windiest area, with northwest winds 20 to 30 mph
with gusts to 40 mph expected until sunset. By Monday morning
the cold front will be east of our CWA and showers will
decrease or end, except in south-central Idaho where they
will linger through the day. Despite the cold front, high temps
Monday will change little from today. Monday night and Tuesday
will be several degrees cooler under mostly clear skies. Monday
will be breezy in and near the western Magic Valley with west
winds 15 to 25 mph in the afternoon. On Tuesday models show
another trough approaching from the northwest, with more
showers mainly in the Idaho mountains Tuesday and Tuesday
night, but less than .10 inch of rain expected.
LONG TERM...Wednesday through Sunday...Warming and drying as
high pressure dominates Wednesday through Friday evening.
Temperatures warm from about 5 degrees above normal Wednesday
to 10-15 degrees above normal by Friday. Friday evening through
next Sunday, as a high amplitude trough approaches the west
coast, it becomes a closed low and follows the coast south.
This will be favorable for a few days of showers and thunder-
storms as the moisture flow remains relatively fixed over the
area. A cold front passage Friday night drops temps to 5-10
degrees below normal next weekend. Models have decent agreement
for the long range forecast, so confidence is high in the
unsettled weather next weekend. Friday evening could be
particularly interesting with the above normal surface
temperatures and high amplitude trough bringing cold air aloft.
Right now, the later timing of the cold front and moisture is
slightly limiting thunderstorm potential Friday evening, but
there is still a 10-20% chance of thunder both Friday and
Saturday evenings.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...DG
AVIATION.....CH
SHORT TERM...LC
LONG TERM....JM
