348
FXUS65 KPIH 190919
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
319 AM MDT Sun May 19 2024

.SHORT TERM...Today through Monday night.
A strong cold front has moved through eastern Idaho this morning
and expect windy conditions behind the front mainly in the Snake
River Plain where a wind advisory is in effect through 6 pm this
evening. Expect 20 to 35 mph wind with gusts 40 to 50 mph. Will
have some travel impacts. Temperatures will cool significantly
today behind the front with highs in the 40s to lower 50s
mountains and upper 50s to lower 60s in the valleys. The upper
level trof associated with the cold frontal passage will move over
Idaho on Monday and do expect some mountain showers tonight and
more widespread showers on Monday afternoon and early evening.
Snow levels will drop to the 6 to 7 thousand foot range and expect
some accumulations above 7 thousand feet in the central mountains.
Minimal travel impacts with the high level snow. Expect isolated
thunderstorms mainly Monday afternoon and evening in the central
mountains as well. Overnight lows tonight into Monday morning
generally in the 20s mountains and 30s valleys but the
combination of lingering winds and cloud cover expect most
locations to stay above freezing in the Snake River Plain. Highs
Monday ranging from the 40s mountains to near 60 in the valleys.
GK

.LONG TERM...Tuesday through next Sunday.
Unsettled and seasonably cool weather will continue through the work
week next week with chances for precipitation each day and highs in
the 40s/50s/60s. The EPS/GEFS and ECMWF/GFS deterministic models
remain in reasonable agreement for early next week showing a H5 low
exiting into Wyoming late Tuesday into Wednesday as a brief
transitory H5 ridge builds in overhead Tuesday night. As a result,
best chances for isolated to scattered showers and thunderstorms
Tuesday will be across ERN Idaho with drier conditions further west
as dry conditions return regionwide for Tuesday night. This break in
the action looks to be short-lived however as a favorable NW storm
track ushers in our next H5 low for Wednesday/Thursday supporting
another round of isolated to scattered precipitation chances.

With respect to 3-day QPF amounts Tuesday through Thursday, the NBM
shows around 0.10-0.40" in the valleys and 0.25-0.75" in the
mountains. While best chances for light accumulating snow will be
above 8500-9000 feet, we may see some light snow potential across
some of our higher elevation mountain valleys in places like Stanley
but generally those higher precipitation/snowfall amounts will
remain confined further north and east outside of our CWA.

Long-range models begin to diverge slightly heading into Friday
through the weekend as attention turns to now a 3rd H5 low working
SE out of WRN Canada. The main differences between the deterministic
GFS/ECMWF centers around the placement of the low with the ECMWF
taking a further northerly and drier track and the GFS taking a
further southerly and wetter track. The EPS/GEFS ensembles maintain
a broad troughing regime overhead which will support unsettled
weather continuing into the weekend with at least isolated
precipitation chances.

Where those models diverge late next week, they begin to come back
to better agreement looking towards early next week with ensemble
models bringing back in a H5 ridge of high pressure to kick off next
week. What that will mean for us will be seasonably cool conditions
through the work week as temperatures begin to see a more well
established warming trend by the weekend heading into early next
week with highs in the 40s/50s/60s climbing back into the 60s/70s
and a lower potential for some low 80s by mid next week. The ECMWF
model continues to be the warmer of the two between that and the GFS
showing better support for the low to mid 80s across our lowest
elevations by mid next week while the GFS keeps us slightly colder
in the low to mid 70s.

Winds through the extended period look to remain on the lighter side
but will be slightly breezy each afternoon with gusts up to around
20-40 mph. We will also have to continue to monitor the potential
for frost/freeze products in between systems as where we get clearer
skies behind exiting cold frontal boundaries. MacKay

&&

.AVIATION...For the 12Z TAFS through 12Z Monday.
Predominant VFR and dry conditions will continue into early Monday
as an upper-level trough begins to work south through MT/ID. This
trough will support an uptick in W/SW winds today to 15-30 kts with
gusts up to 25-45 kts. As the trough begins to shift more directly
overhead tonight into Monday, precipitation chances will begin to
increase supporting isolated to scattered showers and storms. Winds
however will see a decrease on Monday, dropping to 10-15 kts with
gusts up to 25 kts. Skies through the period will remain partly to
mostly clear with CIGS generally around 12-20k feet. MacKay

&&

.HYDROLOGY...A flood warning continues for the Portneuf river in
Pocatello.  A flood advisory continues along the Portneuf river at
Topaz. Water levels are slowly receding for the Portneuf river due
to the snowpack diminishing and slightly overall cooler
temperatures.  River levels for most other big rivers look to
remain the same this week, if not slightly less, due to overall
slightly cooler temperatures expected this week.
Wyatt

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 7 AM this morning to 6 PM MDT this evening
for IDZ052>054.

&&

$$