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151
FXUS65 KBOI 281619
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1019 AM MDT Tue May 28 2024

.DISCUSSION...
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A cold front will approach the region today, with
warm southwest flow ahead of the front. Temperatures will be
around 15 degrees above normal today. Morning sounding at BOI
was pretty impressive, with 73F at 3500ft, indicative of a warm
airmass, with a nice inverted V sounding. DCAPE values of
1200-1500 J/kg this afternoon will promote environment capable
of producing gusty winds up to 60 mph with any showers or storms
(downdrafts) that form, along with areas of blowing dust. CAMs
models showing updraft helicities over NE Oregon this afternoon,
favorable for hail up to 1 inch. Less of a threat for hail over
the Idaho zones today. Cold front moves through this evening
bringing northwest winds behind the front. Showers linger over
the central ID mountains into Wednesday morning. Temperatures
cool around 15-20 degrees on Wednesday with dry conditions.
Breezy northwest winds continue Wednesday, especially during the
afternoon.
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&&

.AVIATION...
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Scattered showers and thunderstorms this
afternoon/evening will be capable of producing heavy rain, small
hail, and gusty outflow winds up to 50 kt. Conditions mainly VFR
with reductions to MVFR/IFR in heavier rain showers. A cold front
passage tonight into Wednesday morning will support lingering
showers over the W Central Mtns. The front will keep winds gusty
overnight through Wednesday. Surface winds: SW-SE 5-15 kt becoming
mainly SW-W after 20Z, except variable gusty/erratic winds near
thunderstorms. Overnight W-NW 10-15 kt with gusts to 30 kt. 10k ft
MSL winds: SW 15-25 kt.

KBOI...20% chance of thunderstorms in the vicinity between Tue/22z
and Wed/00z, increasing to 50% until Wed/04z. Development of storms
will be mostly sporadic, but may become more organized if a strong
outflow develops. While 50 kt outflow gusts are a possibility (5%
chance), they are most likely to be between 30-40 kt. Winds SE
around 12 kt becoming NW 12 kt after 20z, except variable gusty
winds near thunderstorms. Overnight winds stay NW at 12-15 kt with
gusts to 20-25 kt.
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&&

.PREV DISCUSSION...
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SHORT TERM...Today through Thursday night...Active weather is
anticipated today as an upper level trough over the eastern
Pacific moves inland today. Southwest flow aloft will strengthen
as this feature approaches southeast Oregon and southwest
Idaho, bringing even warmer temperatures and increasing
moisture. Highs will reach the upper 80s in the lower valleys,
with a 20-40% chance to hit 90 degrees. Instability will
develop this afternoon ahead of the trough, and shower and
scattered thunderstorm development will favor the higher
terrain. However, the approaching trough will provide lift for
storm formation and will aid storm organization and movement
into lower valleys including the Treasure and Magic valleys.
Storms may become strong to severe with wind gusts to 60 mph the
primary hazard, but hail and heavy rain will also be possible.
Showers and thunderstorms will decrease overnight as the trough
and a cold front push through, with most activity limited to the
central Idaho mountains after midnight MDT. The cold front will
move across the area this evening, reaching the Magic Valley
near or shortly after midnight MDT. Gusts to 45 mph are possible
along the front, but could be stronger if thunderstorm outflows
enhance the front. This may result in blowing dust reducing
visibility.

Much cooler and drier air will arrive behind the cold front on
Wednesday. Dry conditions will return with temperatures nearly
20 degrees cooler than today. Winds will be breezy as the trough
passes through, bringing gusts 20-30 mph, except up to 40 mph in
the Magic Valley. Thursday will be very similar to Wednesday as
dry northwest flow aloft sets up behind the trough, keeping
temperatures around 5 degrees below normal. Additionally, winds
will be lighter, but still breezy across the Magic Valley.

LONG TERM...Friday through Tuesday...Models are in generally good
agreement with regard to the large-scale pattern through early next
week, but there are some differences with respect to short-wave
troughs embedded in a westerly flow aloft. A weak upper trough could
move through over the weekend, but precip chances remain slim (less
than 20 percent) and confined to the far north. A more impressive
trough could arrive early next week, but there are significant
differences in its strength. There is a low (15-30 percent chance)
of rain showers across the northern areas starting Sunday night and
continuing into Tuesday. Near normal temperatures are favored on
Friday, warming to slightly above normal temperatures for the
remainder of the period. There is at least a 60 percent chance that
high temperatures exceed 80F in portions of the Snake Plain from
Saturday until Tuesday, including Boise.
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&&

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

&&

$$

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