553
FXUS65 KPIH 160950
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
350 AM MDT Mon Sep 16 2024

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...
Folks...Fall is almost here! At least as far as the forecast is
concerned. A series of low pressure systems remain on tap this week
bringing widespread showers and thunderstorms, and much cooler
temperatures. Today will be a last gasp of summer as high temps make
a run at 75-80 for most lower elevation and valley population
centers. A lull in shower activity is expected this morning through
early this afternoon with some breaks of sun, before isolated to
scattered showers and thunderstorms return. The atmosphere isn`t
perfectly set up as either a dry-microburst or wet-microburst
environment this afternoon/evening, but the HREF wind gust max does
simulate some convective outflows/downdrafts in excess of 50 MPH
(likely mostly coming from the HRRR), and forecast soundings hint at
varying degrees of increasing shear as evening approaches with
locales that see sunshine potentially building up 500-1000 J/kg of
MUCAPE. Messy...but the right combination of ingredients all
together in the right place could result in a strong to borderline
severe storm. All things considered, strong wind gusts in excess of
50 MPH and heavy rainfall seem to be the top hazards with storms
today. Tonight this activity will trend even more widespread,
culminating Tuesday in scattered to widespread shower activity with
a few embedded thunderstorms regionwide, and much cooler high temps
only reaching the upper 50s to low 60s. Storm total QPF amounts are
expected to reach 0.15 to 0.40 inches in lower elevations like the
Snake Plain and Raft River area, and 0.50 to 1.00 inches across many
of our mountain ranges...which should damper ongoing wildfire
activity. While flooding is not expected to be a widespread threat,
we will need to watch recent burn scars and any areas impacted by
multiple thunderstorms (or training thunderstorms) for localized
issues due to higher rainfall rates and totals. 01

.LONG TERM...WEDNESDAY THROUGH NEXT MONDAY...
Next low in series rotates into the Great Basin Wednesday, then
shifts east Thursday into Friday. Moisture could remain trapped
around the low, which may be too far south to truly impact East
Idaho however there is enough uncertainty to keep a chance of
precipitation across the region both days. East Idaho remains
under the influence of northwest flow into the weekend, with cool
temperatures each day. There are a series of weak shortwaves that
pass through the region by the weekend. The GFS and ECMWF have
been trending drier, but the ensemble clusters still show
potential for a deeper trough to develop similar to the systems
early this week. Thus there is still a chance for some showers
moving into the weekend. There is high confidence that
temperatures remain cool for the entirety of the extended period,
with highs generally in the 60s for lower elevations. DMH

&&

.AVIATION...
Showers and a few thunderstorms working through East Idaho early
this morning. Should see precipitation gradually diminish through
about sunrise, then a brief break for the remainder of the morning.
Thunderstorms redevelop this afternoon, with gust potential over
45kts along with very heavy rain. Precipitation gradually becomes
more widespread and heavier overnight. CIGS remain VFR overall, but
stronger storms could briefly lowering CIGS and VIS to MVFR. DMH

&&

.FIRE WEATHER...
Moisture will continue to stream into East Idaho today with
another round of thunderstorms. Some of the storms may be strong
this afternoon and evening, with wind gust potential over 50 MPH
and locally heavy rainfall. Precipitation becomes more widespread
and heavier through the night tonight, and most areas in East
Idaho appear to have a greater than 70% chance of wetting rain by
sunrise Tuesday. 24-hr total precip by that time should fall
generally between 0.1-0.35" of rainfall, but some locations could
see more especially given thunderstorm influence this afternoon
and evening. The rain continues into Tuesday, along with
temperatures continuing to fall with highs only in the lower 60s
for most lower elevation locations. Cooler unsettled conditions
continue into Wednesday and Thursday as another low crosses the
region. There is some potential for drying late in the week into
the weekend, but there is also some uncertainty on the potential
of another trough arriving by the weekend. What is confident
however, is temperatures remaining seasonably cool for the
remainder of the week. DMH

&&

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

&&

$$