Scattered showers and thunderstorms before 3pm, then showers likely and possibly a thunderstorm between 3pm and 5pm, then scattered showers and thunderstorms after 5pm. Snow level 10300 feet. Mostly cloudy, with a high near 57. South southeast wind 8 to 11 mph, with gusts as high as 21 mph. Chance of precipitation is 70%.
Forecast discussion
585
FXUS65 KPIH 041032
AFDPIH
Area Forecast Discussion
National Weather Service Pocatello ID
432 AM MDT Sun May 4 2025
.KEY MESSAGES...
- Cooler Weather Through Tuesday
- Showers & Thunderstorms Increase Today Through Tuesday
- Windy Conditions Monday
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 214 AM MDT Sun May 4 2025
Showers and thunderstorms will increase west to east later today
as the split flow system slowly works farther inland. Localized
heavier rain and gusts over 45 mph (30-50% chance of
occurrence) are possible with stronger storms, especially as
they cross the Snake Plain...likely due to maximized
instability and slightly drier air over the Plain. Overnight, we
will see the bulk of the showers shifting into the central
mountains and southwest Montana. For Monday and Monday night,
the dominant southern low deepens near the Four Corners...while
the northern end of the split continues across Canada. We will
see a smaller secondary low develop and drop south across
eastern Idaho. This will increase shower potential and also
create a window of stronger winds. At the moment, we are looking
at winds becoming more northwest to north during the afternoon
and evening hours. The current forecast has speeds pushing into
WIND ADVISORY territory across the INL and north toward Monida
Pass. We will see if this trend continues later today and look
more at the potential for issuing an advisory. Snow levels
remain pretty high except across the central mountains tomorrow
morning, where enough colder air filters in briefly to push them
down to 6000-8000ft. With the low pulling farther away tomorrow
night, snow levels drop to 6000-7000ft up north and closer to
8000-8500ft along the Utah border.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 214 AM MDT Sun May 4 2025
Models continue to show another closed low developing over
the region Tuesday (somewhat embedded in the overall trough
affecting southeast Idaho in the Short Term period
above)...increasing chances for showers and isolated thunderstorms
to linger Tuesday, especially in the southern and eastern highlands.
Broad ridging is still expected to take over thereafter...supporting
a warming trend with some readings over 80 degrees returning from
Thursday onward. As far as other weather impacts...there still
appears to be quite a bit of moisture running around under the ridge
with a few shortwave troughs also passing by to our north, all of
which make this a "messy" high pressure scenario. Hard to completely
rule out at least isolated showers or thunderstorms during an
afternoon or two somewhere in the forecast area, but confidence is
very low in the details at this time. The overall chance of
thunderstorms may tend to increase next weekend.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 432 AM MDT Sun May 4 2025
Our long-advertised low pressure storm system finally arrives today,
and will linger over the region for the next several days as well.
Today...expect varying degrees of mid to high-level clouds and
increasingly breezy conditions out of the southwest (especially at
KBYI/KIDA/KPIH with lighter winds potentially going northwest for a
few hours at KDIJ), although all terminals should remain solidly VFR
for most of the day. The main aviation impact will come with showers
and thunderstorms developing and tracking from southeast to
northwest this afternoon/early this evening. Have retained the
general structure of the previous TAFs for this period with
predominant -SHRA everywhere but KSUN for a several hour period
generally starting between 20-22z/2-4pm depending on the airport,
with then a 2-4 hour PROB30 for -TSRA, and just slightly adjusted
start/end times for everything based on the latest high-res
simulated reflectivity forecasts. HREF ensemble max wind gusts are
pinging 50+ MPH in a few isolated spots with these thunderstorms in
the general corridor from the southern highlands northwest across
the Snake Plain, so have increased potential gusts to 35kts in the
PROB30s for KPIH and KIDA (30kts at KBYI and KDIJ). Unfortunately
it`s impossible to say EXACTLY where these stronger storms/stronger
gusts will occur and inappropriate to try to infer that type of
detail from the CAMs...the spots gusting highest will change again a
bit with the 12z HREF run. Overall we didn`t have much support in
really any of the guidance for low cigs even during the predominant -
SHRA periods this afternoon so we trended/nudged cigs slightly
higher in the latest forecast, but admittedly our confidence in the
cig forecast is rather low as guidance such as the NBM and even the
HRRR don`t seem to reflect this afternoon`s convection at all in
their cigs. Still think we could certainly see brief MVFR hits with
any thunderstorms moving very near/directly over terminals, so
retained that in the PROB30s. Consensus is good that this activity
will lift further north this evening allowing the region to trend
drier with cigs quickly returning to VFR and even breaking up
overnight...have retained VCSH overnight everywhere but KSUN for now
based on a few CAMs showing a few stray showers. NBM guidance
supports lowering cigs again around/just after 12z/6am Monday
morning (possibly modestly low stratus development in the now more
moist low-level airmass?), but confidence is low in this scenario at
this time and it`s just beyond the current TAF period. We will
continue to evaluate this in future forecast updates.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Keyes
LONG TERM...KSmith
AVIATION...KSmith
Nearest avalanche forecast regions
Logan
13mi away by Utah Avalanche Center
No data reported
Ogden
52mi away by Utah Avalanche Center
No data reported
Greys River
71mi away by Bridger-Teton Avalanche Center
No data reported
Salt Lake
89mi away by Utah Avalanche Center
No data reported
Uintas
98mi away by Utah Avalanche Center
No data reported
Provo
114mi away by Utah Avalanche Center
No data reported
Tetons
114mi away by Bridger-Teton Avalanche Center
No data reported
Togwotee Pass
135mi away by Bridger-Teton Avalanche Center
No data reported
Island Park
166mi away by Gallatin NF Avalanche Center
No data reported
Soldier & Wood River Valley Mtns
173mi away by Sawtooth Avalanche Center
No Rating - Watch for signs of unstable snow such as recent avalanches, cracking in the snow, and audible collapsing. Avoid traveling on or under similar slopes.
