Area Forecast Discussion
Issued by NWS Boise, ID

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883
FXUS65 KBOI 200250
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
850 PM MDT Sun May 19 2024

.DISCUSSION...The light shower activity has expanded into
northern Malheur County this evening and the forecast was
updated to account for this trend. The showers end by midnight
based on the latest hi-res model guidance. The core of an upper
low pressure system will move through central Idaho on Monday.
The system will support a 15-30 percent chance of showers in the
SW Idaho valleys and a 30-60 percent chance of showers in the
central Idaho mountains. Snow levels near 5000 feet in the
morning rise to 6000 feet in the afternoon. There is minimal
support for thunderstorms, but enough for a slight chance (less
than 20 percent) in the afternoon. Gusty winds up to 40 mph
will accompany the storms. High temperatures will be slightly
warmer, but still 5 to 10 degrees below normal. Winds increase
through the late morning into the afternoon, with widespread
north-northwest winds of 15 to 25 mph.

&&

.AVIATION...Mainly VFR. Isolated to scattered showers will
continue across the central ID mountains tonight into Monday
morning. Showers will increase and expand in coverage on Monday,
mainly across southwest ID, with isolated thunderstorms also
developing. Mountains obscured in showers. Snow levels 5-6kft
MSL. Surface winds: W-NW 10-20 kt, with gusts to 30 kt Monday
afternoon. Gusts to 40 kt possible near thunderstorms. Winds
aloft at 10k ft MSL: NW 10-20 kt.

KBOI...VFR. Showers developing Monday afternoon over the
foothills, with a 20% chance of showers reaching the terminal.
Prescribed fires in the Boise foothills may bring haze and
reduced visibility aloft. NW winds overnight, becoming gusty by
late Monday morning.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Tuesday night...As one wave exits
eastward another wave will push through the region tonight and
Monday. This system will support a broad 20-50% chance of
showers and thunderstorms Monday afternoon across far SE Oregon
and much of SW Idaho. The thunderstorm threat remains minimal,
15-20%, but storms that form could bring gusty winds to 40 mph.
Outside of thunderstorms winds will ramp up Monday afternoon,
becoming sustained 10-20 mph with gusts of 25-30 mph across a
broad area. Tuesday is dry and not as windy in response to a
passing shortwave ridge. This break is shortlived as the next
low pressure system will push a cold front and precipitation
into the area Tuesday night with snow levels around 7kft MSL.
Temperatures will warm slightly each day through Tuesday.

LONG TERM...Wednesday through Sunday...An upper low will track
through the Pac NW on Wednesday bringing widespread showers and
possible afternoon thunderstorms. A reinforcing cold front will
cross the region late Wednesday as the low pushes through
Idaho. This frontal passage will cut off much of the
precipitation across lower elevations while e-central Oregon
and w-central Idaho keep a 30-60% chance of rain and snow
through Thursday. With better model agreement on the low track
through NE Oregon and central Idaho, QPF amounts have trended
lower along the I-84 corridor and areas to the south and west
for Wed/Thur. Snow levels of 6-7kft MSL on Wednesday will fall
to 4500-5500 feet on Thursday. That said, any notable
accumulation will be limited to higher peaks above 6500ft MSL
where totals of 3-8 inches are expected through Thursday. The
pattern remains active, through the weekend with the next cold
low dropping into the Pac NW on Saturday. The current forecast
track would again place the focus of heavier precipitation
across e-central Oregon and the w-central Idaho mountains.
Winds will remain breezy, increasing each afternoon across open
and higher terrain. Temperatures will be below normal through
the weekend, with Wednesday and Thursday the coolest days at
10-15 degrees below normal.

&&

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

&&

$$

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DISCUSSION...BW
AVIATION.....ST
SHORT TERM...DG
LONG TERM....DG