616
FXUS65 KPIH 162044
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
244 PM MDT Thu May 16 2024

.SHORT TERM...Today and Friday.
There is weak high pressure over southeast Idaho with zonal flow
aloft. There is a a trough with a dry slot over the Pacific ocean
just off the Washington coast. This trough is associated with an
Upper Level Low over central British Columbia.

With zonal flow aloft, west southwest winds have picked up across
the area this afternoon with gusts of around 20 to 30 mph. A lake
wind advisory for the American Falls reservoir remains in effect
until early this evening. Temperatures are in the low to mid 70s
across our lower elevations, about 4 to 8 degree above normal.
This will be warmest temperatures for a while, likely over a week.

By Friday, models continue to show the wave currently just off
the Washington coast moving over northern Idaho and northern
Montana. Still looking for scattered showers and isolated
thunderstorms late Friday morning into Friday afternoon mainly for
the Island Park area. The rest of the area still looks dry with
this next system. The bigger impact will be the winds. Looking
for sustained winds of 25 to 45 mph with gusts of around 35 to 60
mph across the area on Friday afternoon. Have a wind advisory for
most of our valley zones and a high wind warning for the Arco
desert, the Upper Snake plain, and Lower Snake plain. Look for
winds of 35 to 45 mph with gusts near 55 to 60 mph for these areas
in a high wind warning on Friday afternoon. There is a 60 to 80
percent chance according to the NBM model for sustained winds of
40 mph Friday afternoon for areas in the high wind warning. Peak
winds will occur around 1 to 4 pm. Expect blowing dust across the
area, especially north of Idaho Falls on I-15. See High wind
warning for more impacts. Temperatures on Friday will drop 5 to 10
degrees, becoming near normal to slightly below normal.
Wyatt

.LONG TERM...Saturday through next Thursday.
The long term period begins with an upper low situated over
Washington with southern Idaho experiencing breezy west to southwest
surface winds under zonal flow aloft. Winds will increase on Sunday
as a shortwave trough approaches and a cold front passes. Models
show precipitation spanning the northern and eastern extents of our
CWA Sunday through Tuesday as the main upper low rotates along the
US-CA border, with National Blend PoPs mostly ranging 35 percent and
lower. Late Tuesday into early Wednesday looks to be mostly quiet
behind the departing low and ahead of the next system. A well-
organized low will drop south into the Pacific Northwest before
shifting eastward and moving directly over Idaho on Thursday, making
this the day with the greatest and most widespread chances for
precipitation in the extended timeframe. While 500 mb ensemble
clusters indicate that around 90% of total members feature troughing
over Idaho, solutions do show differences predominately in the depth
of the trough. Daytime highs will run 5 to 10 degrees below normal
the first part of the week before rebounding back to climatological
norms by mid-week. However, those temps won`t last as the next
system brings highs back down into the 40s and 50s for next
Thursday.
Cropp

&&

.AVIATION...
VFR conditions forecast with FEW to SCT mid- to high level clouds.
Winds will continue to increase through early evening, becoming
light after sunset. A dry cold front passage Friday will bring
strong WSW winds to much of SE Idaho, with sustained winds 25 to 35
kts and gusts to 50 kts peaking between 19z and 22z.
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. Water levels for other rivers,
including the Big Wood, Big Lost, Henrys Fork, Teton, and Snake,
are slowly climbing due to snowmelt, but all rivers look to remain
below action stage with current forecasts.
Wyatt

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon to 8 PM MDT Friday for Id`s-055>058-
062-065-067-068-070.

High Wind Warning from noon to 8 PM MDT Friday for Id`s>054.

&&

$$