Red Flag Warning 6, NWS Pocatello, ID

Area Forecast Discussion
National Weather Service Pocatello ID
221 PM MDT Thu Jul 14 2022

.SHORT TERM...Tonight through Friday night.

HREF members showing good agreement on firing off convection this
afternoon in two areas. First areas is across the south hills into
the southeast highlands, roughly parallel to I-86. The second area
is further north from roughly Dubois to Island Park. Strong
monsoonal moisture noted over the region with precipitable water
values around 0.75" and morning dew points in the 40s and 50s. DCAPE
values are running in the 1500-2000 J/kg so microburst are the main
threat this afternoon. Rainfall amounts generally expected to be
less than 0.10". A few, isolated slow-moving cells could have
rainfall totals of up to 0.20" as indicated by the HREF's 90th
percentile rainfall amounts. Expect most convection to dissipate
early to mid evening. However some nocturnal showers are possible
overnight with models showing the most likely areas across the
central mountains and southeast highlands. Rainfall amounts likely a
trace of a couple hundredths overnight.

Similar setup for Friday, as monsoonal moisture setup a little more
across the southeast highlands. Limiting factor could be cloud
cover, depending upon how much pushes into the area and how long it
takes to mix those clouds out. Still models hinting at isolated to
scattered convection across the southeast highlands. Once again
models indicating area from Dubois over to Island Park for storms
once again. Temperatures are pretty comparable to today at most
locations. Heat risk index is in the moderate category, similar to
today, so will hold off on issuing what would be a marginal heat
advisory.

13

.LONG TERM...Saturday through Thursday. Shortwave pushes east past
Idaho Friday night, shunting off northward progression of monsoonal
flow and allowing drier and slightly more stable airmass to shift
across the region. Upper trough sags into the PacNW region with low
centered near Seattle by Sunday afternoon. Flow turns more southerly
again, allowing moisture to surge back north into the region for
next round of thunderstorm activity. Upper trough drives east along
the Canadian border Monday, flattening the ridge and setting up a
drier zonal flow pattern through midweek. Breezy to windy conditions
are expected into midweek, and have adjusted forecast above NBM for
Monday and Tuesday. Shifting into Wednesday and Thursday, the GFS
and ECMWF begin to diverge solutions with a potential trough moving
into the coast. ECMWF is more aggressive with the feature, leading
to an increased southerly flow, which would result in potential
increased monsoonal flow through the Great Basin. Ensemble clusters
split as well into the latter part of the week. Stayed the course
with NBM values across the board for both Wednesday and Thursday.
DMH

&&

.AVIATION...Isolated to scattered thunderstorm activity continues
this afternoon and evening. All terminals except KSUN carry at least
VCTS through 03Z. Gusty winds greater than 40kts remain main threat,
though small hail also possible, and ceilings should remain MVFR or
better. There is potential for redevelopment of light showers toward
sunrise Friday morning, similar to activity earlier today.
Confidence is low that this activity would impact terminals until
after 18Z so have left VCSH out of forecast for now. DMH

&&

.FIRE WEATHER...Isolated to scattered thunderstorm activity
continues this afternoon into the evening with erratic gusty winds.
Storms will be a mix of wet and dry, with the better chances for wet
thunderstorms occurring across the Southern Sawtooth and Caribou
NFs. Red Flag Warning remains in effect for Zones 427 and 413 where
fuels are critical and thunderstorm chances are the highest. Similar
conditions exist for Friday as another disturbance shifts across the
region. Another Red Flag Warning may be necessary for Zone 413. Flow
aloft is expected to shunt most of the moisture east of the region
for Saturday. Southerly flow increases ahead of another disturbance
Sunday, allowing another round of monsoonal moisture to surge north
for potential return of thunderstorm activity. This feature drives
east along the Canadian border into the northern plains late Sunday
into Monday. Drier air mass is expected for Monday and potentially
beyond, but also a greater threat for combination of strong winds
and lower humdities at least Monday.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for IDZ413-427.

&&