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000
FXUS65 KPIH 242012
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
212 PM MDT Wed Apr 24 2024

.SHORT TERM...Today and Thursday.
There continues to be an upper level low off the Central coast of
California, which is bringing moisture and instability into our
area in southwest flow aloft. Farther, north and west off the
Pacific coast of Oregon there is a low system and associated
moisture and frontal boundary.

This afternoon into early evening, expect isolated showers and
thunderstorms for our northern areas and scattered showers and
thunderstorms (SB CAPE of 250 to 500 J/kg) for our southern areas,
generally south of the Eastern Magic valley and Snake plain. With
dry air in place especially at the surfaces (PWATs around
0.40-0.80), look for gusty outflows up to around 40 mph this
afternoon into early evening with showers and thunderstorms. Also,
expect small hail and brief moderate to heavy showers with any
storms. Temperatures will be 8 to 12 degrees above normal today,
the warmest temperatures for at least a week (next Wednesday).

Look for isolated overall light convection this evening into
tomorrow morning. Thursday the system off the Oregon Pacific coast
starts to approach. This system will bring drier air and breezy
winds out ahead of it. The moisture with this system isn`t
expected until late Thursday into Friday. Thursday, especially in
the afternoon, due to residual moisture and instability from
today, look for isolated to scattered showers and thunderstorms
mainly along the Eastern Highlands from the Snake plain to the
Wyoming border. Look for breezy afternoon conditions (wind gusts
of 20 to 35 mph) for our western areas, especially the Eastern
Magic valley. Not much, if any, precipitation is expected in the
Eastern Magic valley Thursday. Only a very isolated chance of
precipitation is expected in our western mountains Thursday.
Temperatures will be cooler Thursday than today, just a few
degrees above normal.
Wyatt

.LONG TERM...Friday through next Wednesday.
Precipitation chances will become increasingly widespread and
increase on Friday as the trough axis shifts overhead. Daytime temps
will decrease by another 5 to 10 degrees on Friday following a cold
front passage. After that, temperatures look to remain fairly stable
for Saturday before they begin to trend slightly warmer again. While
500 mb ensemble clusters still feature differences regarding the
timing and depth of the next low working into the PNW and a ridge
building in from the west/southwest, the majority of the solutions
feature some degree of more westerly/zonal flow over Idaho early
next week as these two upper level features struggle to take
control. Models do show southwest 700 mb winds increasing to around
30 mph which will support breezy conditions at the surface.
Depending on which feature dominates the pattern over Idaho will
directly impact forecast temperatures and precipitation early next
week. Deterministic models do show light precipitation signatures
filtering into Idaho under southwest flow aloft, with the
deterministic NBM carrying widespread PoPs up to around 40% through
this period along with fairly stable daytime highs early next week
just above normal.
Cropp

&&

.AVIATION...
VFR conditions forecast throughout the period, although any moderate
rain or storm to directly impact a terminal could reduce conditions
below VFR. Mid-level and high clouds will increase as moisture
filters in from the southwest today. Hi-resolution models show a
band of rain showers filling in from east to west across all
terminals beginning around 18z. Isolated to scattered thunderstorms
will favor the corridor from KBYI, KPIH, over to KDIJ with less
chances of thunder further north. HREF thunderstorm probabilities
increase later into the afternoon to as high as 50% to 60% near the
aforementioned terminals. Winds will remain light to breezy outside
of any gusts associated with thunderstorms or outflows, which could
reach as high as 40 kts.
Cropp

&&

.HYDROLOGY...
No changes in the hydro forecasts at this time. Water levels on
the Portneuf river continue to run high, just below moderate flood
stage for the Portneuf river in Pocatello. The river forecast for
the Portneuf river in Pocatello shows the river running above
flood stage for the foreseeable future and likely climbing back to
moderate flood stage by Thursday and peaking Sunday at around
10.5 feet or midway through moderate flood stage. At Topaz on the
Portneuf, current levels are slightly above minor flood stage.
Water levels are forecast to slowly rise toward the end of the
week with warming temperatures through Wednesday and the return of
precipitation chances in the second half of the week into the
weekend.
Wyatt

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$