Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 292001

Area Forecast Discussion
National Weather Service Pocatello ID
201 PM MDT Wed Jun 29 2022

.SHORT TERM...Tonight through Thursday night. Persistent southwest
flow in place through Thursday night behind cold frontal passage
early this morning. A few weak showers linger across the
highlands mainly east of I-15 in response to shortwave lifting
through western Montana this afternoon, but clearing slowly
spreading east across the region. Winds have finally reached
lower thresholds for Wind Advisory in the Arco Desert, so will
continue headline through evening as planned. High- res models in
favor of continuing shower activity through the night for the
southeast corner as another very weak feature interacts with a few
pockets of mid level instability. The area of mid-level
instability expands across most higher elevations Thursday
afternoon but best moisture confined to the southeast corner for
continued threat of thunderstorms. Precipitation should be
extremely limited with convection remaining isolated and most of
those producing very little moisture given dry lower atmosphere.
Gusty winds likely to remain main threat but severe gusts not
anticipated. DMH

.LONG TERM...Fri through next Tue night. There is a plume of
moisture from the Gulf of California expected to penetrate into the
central Rockies, but is shunted to the east on Fri in northern Utah.
This bears some watching as a change of only a hundred miles could
make a difference for the southern highlands. In fact, the
deterministic ECMWF does generate some PoP for even the central
Idaho mountains. A Pacific upper level low slowly moves eastward,
and by Sat it is starting to put a more southerly component to the
upper level wind. Also as it gets closer, the strength of at least
the upper level wind is also increasing. This gives a gradual
greater and greater threat for afternoon and evening showers and
thunderstorms, but no period sees anything higher than chance
wording even for showers, as there is no cold front really seen; it
will be a matter of where the Gulf of California moisture goes that
determines who receives showers and thunderstorms. On Independence
Day, a trough rotates around the now-closed low along the WA coast.
This increases the wind, but showers and thunderstorms on that
afternoon appear limited to the central Idaho mountains. With the
troughing there is a slight cool-down for the day on Mon, from
around 90s on Sat and Sun to middle 80s for the Snake River plain
locations. After the holiday, upper level ridging returns fairly
strongly, and 90 degree temperatures have returned and wind has
decreased. Messick


.AVIATION...What few alto-level clouds are around should disappear
during the afternoon today, with another round of high clouds
arriving in the morning, arriving 30/09Z in the west and 30/15Z in
the KDIJ area. It will mostly cover southern areas, with KSUN
staying pretty much cloud free for the TAF period. Only KDIJ has a
threat of TS in the area this afternoon and evening. Winds are
strong, but in line with the major runways. By early evening, the
wind should subside, and most locations for late tonight will have a
period of variable wind, followed by a north to east flow as
airdromes open up Thu morning. Messick


.FIRE WEATHER...Dry westerly and southwesterly flow will reduce the
thunderstorm activity to limited areas along the Montana and Utah
borders, and not going above slight chance. The westerly flow is
preventing a warm up until the flow shifts to more southerly on
Friday. The shift is coming due to a deep low off the west coast
moving closer to shore, and finally reaching the WA coast on Mon. As
this low moves closer, the flow gets more southerly, bringing in
moist and unstable air.  It also increases in strength, and will be
reflected with gustier and strong wind each afternoon. Thunderstorms
and showers are mainly in the mountains and highlands, but on Sat
the Snake River plain has a slight chance of showers and
thunderstorms. Messick


Wind Advisory until 8 PM MDT this evening for IDZ052.


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