411
FXUS65 KPIH 181910
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
110 PM MDT Sat May 18 2024

.SHORT TERM...Today and Sunday. There is zonal flow aloft over
southeast Idaho with a very weak trough currently moving over
northern Idaho. Further upstream, there is another slightly
stronger trough just off the southern British Columbia coast.

Look for dry and breezy conditions today. Gusts will generally be
around 20 to 30 mph across the area. The Arco desert will see
gusts briefly around 40 mph this afternoon. High temperatures
today will be near to slightly above normal with upper 60s to
lower 70s in lower elevations and upper 50s to lower 60s in the
mountains.

Tomorrow, Sunday, models show the trough currently off the
southern British Columbia coast moving over central Idaho starting
early morning and exiting our area by early to mid afternoon. Look
for scattered showers and isolated thunderstorms over the Montana
Divide in the morning through late afternoon/early evening. Winds
look stronger on Sunday afternoon with sustained winds of 20 to 30
mph and gusts of around 30 to 40 mph. Some gusts could be around
50 mph, especially for the southern Arco desert, southern Upper
Snake plain, and northern Lower Snake plain. A wind advisory is in
effect for the Arco desert, Upper Snake plain, and Lower Snake
plain for Sunday morning through Sunday afternoon. High
temperatures Sunday will drop around 10 degrees from Saturday
with mountains highs in the 40s and 50s and valleys in the upper
50s to lower 60s.
Wyatt

.LONG TERM...Monday through next Saturday.
The extended timeframe will remain active/unsettled, with multiple
lows bringing precipitation chances and cooler temperatures about 5
to 10 degrees below normal. Models show a closed low forming over
southern Idaho late Monday into early Tuesday as a trough shifts
eastward, which will support more widespread precipitation chances.
Tuesday into early Wednesday will be a brief break in between
systems, with weak high pressure or zonal flow over Idaho. A well-
organized low will drop south into the Pacific Northwest on
Wednesday. Models continue to features timing differences with
regard to how quickly they bring the closed low over Idaho on
Thursday/Friday, with the GFS now showing a slightly faster
progression. Both GEFS and EPS show 3-day QPF totals through
Thursday evening ranging up to around 0.70" in the E and SE
highlands and central mountains and 0.15" outside of these areas.
Most of that will fall as rain across the area, but snow will
accumulate in the central mountains at or above 8,000 feet
elevation. The National Blend indicates overnight temperatures will
drop into the low to mid-30s both Thursday and Friday morning, which
could prompt another round of Frost/Freeze products for our
agricultural zones. Zonal flow returns Friday and Saturday with
daytime highs increasing to within a few degrees of normal by late
next week.
Cropp

&&

.AVIATION...
VFR conditions forecast through the period. Mostly clear skies will
turn to FEW and SCT as mid-level and high clouds increase this
afternoon. Westerly winds will become breezy today between
approximately 18z and 02z, with gusts to around 25 kts. Chances for
light rain showers near KDIJ will arrive around or just after
Midnight tonight. Winds will be breezier tomorrow, increasing as
early as 11z in the morning.
Cropp

&&

.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 to 6 PM MDT Sunday for IDZ052>054.

&&

$$