971
FXUS65 KBOI 191524
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
924 AM MDT Wed Jun 19 2024

.DISCUSSION...Continued warming and drying through Thursday
even with an upper trough still over the area, but the main
reason for the warming is deeper than normal thermal low
pressure at the surface. The trend will slow down Friday as
a weak upper trough passes north of us, but Saturday will be
hotter again, and Sunday almost as hot. We now see a 40-60
percent chance of reaching 100F Saturday in the Treasure
Valley. A Heat Advisory has been considered but nighttime low
temps should be higher. After Sunday we see several more days
of 90s in the valleys and 80s in the mountains before a stronger
upper trough brings about ten degrees cooling. Models faintly
hint at thunderstorms along the ID/NV border and
Valley County/ID late Thursday, then slightly more in western
Idaho Thursday night (not yet in our forecast). The hottest day,
Saturday, looks mostly sunny until evening when instability for
thunderstorms increases in northern areas. No updates for now.

&&

.AVIATION...FR. Some mid-level cumulus cloud development over
high terrain this afternoon. Surface winds: E-SE 5-10 kt, then
variable less than 10 kt after Thurs./03Z. Winds aloft at 10kft
MSL: SW-SE 10- 15 kt.

KBOI...VFR with a few high clouds. Surface winds: SE 8-10 kt
becoming variable less than 5 kt after Wed./22Z.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Friday night...The warming trend
will persist in the short term under a weakening upper-level
trough. Clear skies will contribute to a temperature increase
of about 10 degrees today, bringing temperatures just above the
seasonal average. On Thursday, temperatures will rise by
another 7-9 degrees ahead of a weak trough expected to pass
through Thursday night into Friday. This weak system moving to
the north will moderate Friday`s warming, resulting in valley
temperatures in the low to mid-90s. Limited moisture will likely
prevent showers or thunderstorms, but it could be sufficient
for scattered cumulus cloud development on Friday afternoon.

LONG TERM...Saturday through Wednesday...This weekend will be
hot thanks to building heights and southwest flow aloft, with a
few 100 degree highs in the forecast for Saturday and Sunday.
Chances for 100 or higher max temps in the lower Snake Plain
have risen to 25- 50% on Saturday and 35-70% on Sunday, with the
highest chances being in Ontario, along the Snake River, and
the Treasure Valley. An upper low moves slowly to the Washington
coast after Sunday, causing upper level heights to fall
slightly. This will cool us down, with highs in the low 90s
Monday-Wednesday for the Snake Plain. Temps overall will still
be about 5 degrees above normal, however. Even with the
approaching low, the long term remains dry with some afternoon
breeziness in SE Oregon and the Magic Valley.

&&

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

&&

$$

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DISCUSSION...LC
AVIATION.....SA
SHORT TERM...JDS
LONG TERM....JM