299
FXUS65 KPIH 281113
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
513 AM MDT Mon Apr 28 2025

.KEY MESSAGES...

- Light precipitation ending by early this afternoon. Isolated
  storms this afternoon.

- Another weak system for Tuesday into Wednesday.

- Way above normal temps later this week.

- Another chance at more widespread rain next weekend.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 237 AM MDT Mon Apr 28 2025

Models are showing some fog developing across portions of the
eastern Magic Valley this morning. However, think that the coverage
will be patchy enough to not warrant an advisory. With that said,
will monitor and may need to perform an early morning update if the
fog ends up being more widespread and impactful than anticipated.
Otherwise, low pressure system is centered over northern Utah this
morning. We will see some rain and high elevation snow on the back
side of the low move through east Idaho this morning. Snow levels
are sitting around 6500 feet or so. Areas around Stanley on webcams
have had some descent accumulations, although this has been mainly
on grassy areas. Rainfall amounts today look fairly light, generally
0.10 inches or less. Some of the models, such as the HRRR, are
indicating that if we clear out soon enough this afternoon that we
could see a few isolated thunderstorms develop by mid to late
afternoon. Although any storms look pretty weak and probably just
enough for a rumble of thunder. Most of the precipitation should end
by sunset this evening. Temperatures today generally look about
normal.

On Tuesday, another system will approach the area from the
northwest. The central mountains will shadow much of the Snake Plain
and Magic Valley, limiting precipitation chances and amounts. Snow
levels are high, generally above 8000 feet. We may not see
precipitation arrive in east Idaho until late afternoon or evening.
Amounts generally look like 0.10 inches or less in the Snake Plain
and Magic Valley. The mountains and highlands could do a little
better, 0.10 to 0.25 inches are more likely. Temperatures on Tuesday
expected to be about 5 degrees above normal with mid 60s in the
Snake Plain and eastern Magic Valley. Tuesday also looks a bit
breezy, likely sub advisory, with several gusts of 25 to 35 mph
likely.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 237 AM MDT Mon Apr 28 2025

A shortwave trough will continue to affect the region with shower
activity during the day on Wednesday, quickly winding down during
the evening as the system pulls east. This will allow a fairly
strong but short-lived ridge of high pressure to build across the
Great Basin and northern Rockies for Thursday and Friday, securing a
break in our weather with dry conditions and progressively warming
temperatures reaching the upper 60s to low 70s Thursday, and 70s to
near 80 Friday. PoPs start to increase again Saturday, however, as a
large splitting trough of low pressure pushes onshore from the
Pacific. At this time...the southern branch of this split appears to
be the one that will predominantly affect our area as it closes off
into a closed low that could slow down and spin over our region for
several days. This overall trough is negatively-tilted as it
approaches with some dynamics to work with aloft moving into a warm
environment...a broad signal that we MIGHT be dealing with
organized/strong thunderstorm potential Saturday afternoon. At this
early juncture instability looks questionable off the deterministic
GFS and ECMWF, but this is many days out with many synoptic details
regarding the split of the trough and tracks of the associated
features still not set in stone. If this closed low does remain over
our area from Saturday right into early next week, a multi-day
period of precipitation, wind, and cooling temperatures can be
expected with some decent QPF stacking up over time, especially
across our mountain and highland areas. Stay tuned.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 513 AM MDT Mon Apr 28 2025

TAF timing and cig/vsby impacts updated for the band of
rain/snow moving from north to south this morning, affecting
everyone except perhaps KSUN and KBYI which will lie on the
western periphery. MVFR cigs are possible at KIDA and KDIJ with
this feature, with vsbys as low as 3SM at KDIJ as long as
precipitation remains snow. Everyone should trend back to VFR
with clouds breaking up a bit this afternoon, but CAMs do
support development of a few showers and weak thunderstorms.
Instability is highest in the west so have gone with VCTS at
KBYI and KSUN 19-02z/1-8pm. Confidence is low on any direct
impacts at either terminal. Also watching some low stratus this
morning in the eastern Magic Valley affecting KJER...no
confidence on whether this will be able to build into KBYI, but
have hinted at it with FEW010 for now and will continue to
monitor.

&&

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

&&

$$

SHORT TERM...13
LONG TERM...KSmith
AVIATION...01