387
FXUS65 KBOI 210226
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
826 PM MDT Thu Jun 20 2024

.DISCUSSION...Mid and high clouds this evening due to a weak
short wave trough aloft moving eastward across the area.
Sprinkles possible this evening in northern mountains. The
trough will briefly slow the warming trend with Friday only
about 3 degrees warmer than today. But Saturday will be hotter
with an upper ridge building behind the departing trough.
Latest models have Sunday a degree or two cooler than Saturday
but still hot. Further cooling (5 to 8 degrees) Monday behind
a dry cold front, then warming again Tuesday and Wednesday,
with Wednesday almost as hot as Saturday. Models diverge
after that with GFS bringing another cold front and cool
upper trough inland while ECM keeps building the heat through
Friday. Current forecast favors the cooler GFS but confidence
is low. No updates for now.

&&

.AVIATION...VFR. Surface winds: E-SE 5-15 kt. Winds aloft at
10kft MSL: S-SE 10-15 kt.

KBOI...VFR. Surface winds NW 5-10kt, switching to SE 5-10kt
around 21/06Z.

Weekend Outlook...VFR. Hot temperatures will bring high
density altitudes Saturday and Sunday. Surface winds W-SW
10-20kt during the afternoons, light during the night.

&&

.PREV DISCUSSION...
SHORT TERM...Tonight through Saturday night...A weak
shortwave will continue to move across the area today,
bringing increased clouds this afternoon. This will keep a
threat of showers and thunderstorms, mainly over northeast
Oregon over the Blue Mountains, north of Baker City and
McCall in Idaho, and a slight chance of showers and
thunderstorms in southern Twin Falls County and areas east.
Drier air will move in from the west, but there will be
enough moisture for showers and thunderstorms to form over
the central ID mountains and southern Twin Falls County on
Friday afternoon. Then the flow aloft shifts to the
southwest, bringing warmer conditions. There is a 40-60
percent chance of temperatures in the lowest valleys
exceeding 100 degrees on Saturday.

LONG TERM...Sunday through Thursday...The warming trend
continues under southwest flow aloft on Sunday with a
50-70 percent chance of exceeding 100 degrees. A weak dry
cold front moves through on Monday, with several degrees of
cooling. Then, temperatures rebound on Tuesday as a trough
off the Pacific NW coast amplifies the ridge over southwest
Idaho and southeast Oregon. Temperatures warm to near 100
degrees in the lowest valleys on Wednesday. A cool Gulf of
Alaska trough is expected to move inland starting Thursday,
initiating a cooling trend. Ensembles show good agreement
on this shift occurring late next week.

&&

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

&&

$$

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DISCUSSION...LC
AVIATION.....SP
SHORT TERM...KA
LONG TERM....KA