332
FXUS65 KPIH 072040
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
240 PM MDT Fri Jun 7 2024

.SHORT TERM...Tonight through Saturday Night.
Early afternoon satellite imagery shows a broad H5 ridge in place
over the WRN CONUS as a H5 shortwave trough works east across the
NRN Great Basin. This trough will be the main driver of
convection today with radar imagery as of 2 PM showing scattered
to numerous thunderstorms developing across Utah and Nevada with
more isolated activity across the CNTRL Mountains. Convective
initiation in CNTRL and ERN Idaho will take place between 2-5 PM
with a mix of isolated to scattered thunderstorms expected to
develop which will continue through this evening ahead of dry
conditions returning overnight. The convective environment today
is represented well on the HREF model with shows 300-600 J/kg of
SBCAPE and 20-30 kts of 0-6 km shear with both the HRRR/NAM models
showing 7-9 degree/km 700-500 mb lapse rates. These conditions
will remain favorable for microbursts and strong outflow winds in
addition to small hail and brief moderate to heavy rain with the
primary hazard centering around strong wind gusts in excess of
40-50 mph. The HREF model probability of sustained winds greater
than 34 mph shows a 50- 70% chance across the Snake River Plain
south into Utah/Nevada with the HREF ensemble max wind gusts today
showing potential for up to 40-60 mph.

As Friday`s H5 shortwave trough works east into Wyoming for
Saturday, a secondary shortwave will fill in behind but will carry
less moisture with it and as a result, support less thunderstorm
chances across SRN Idaho. For a comparison, the 24-hour HREF
probability of thunder Friday shows around a 40-70% chance
everywhere outside the CNTRL Mountains while the probability on
Saturday drops to a 10-20% chance regionwide with a 20-40% chance
across Cassia County. Stronger storms Saturday will again support
strong wind potential but to a lesser extent versus Friday with
the HREF model probability of sustained winds greater than 34 mph
showing a 10-30% chance. The HREF ensemble max wind gusts Saturday
show potential for up to 30-40 mph.

Courtesy of high pressure overhead through the start of the
weekend, temperatures will remain seasonably warm with highs in
the upper 70s to low 90s each day and overnight lows in the
40s/50s/60s. Outside of any thunderstorm outflow winds, synoptic
winds will remain on the lighter side staying less than 20 mph
each day. MacKay

.LONG TERM...Sunday through next Friday.
The most active and impactful weather in the long term will be
Sunday through Monday where a Pacific system will bring the most
widespread shower and thunderstorm activity. Have some widespread
amounts over 0.10 inches in the two day period. Temperatures will
remain very warm Sunday with low elevations highs in the upper
80s. It will be much cooler Monday with highs mainly in the 70s to
around 80. A dry zonal flow will set up Tuesday through Thursday
and expect dry conditions with some breezy conditions expected
especially in the Snake River Plain. Temperatures will remain
above normal through the long term with a warming trend Tuesday
into Thursday with highs 70s mountains and 80s valleys with some
low elevations near 90 by Thursday. Will see an increase in the
chance for convection and showers and thunderstorms Friday mainly
in the eastern mountains. Highs likely remaining in the 70s and
80s. GK

&&

.AVIATION...For the 18Z TAFS through 18Z Saturday.
Main impact will be thunderstorm development after 20Z and
continuing through much of the evening. Have vicinity at all sites
and expect best chances at site to be at BYI as brunt of activity
in southern regions, but the threat will be at all sites. Main
impacts will be wind gusts near any thunderstorm outflow where
gusts may exceed 30 knots with a low chance of 50 knots right
under a storm. Thunderstorms will end overnight with again
isolated development Saturday afternoon. GK

&&

.FIRE WEATHER...
Warm weather will produce minimum humidity values in the upper
teens to mid 20s through the weekend. Isolated thunderstorms
remains possible through Saturday. A cold front will arrive late
Sunday which will produce better chances for thunderstorms Sunday
afternoon and Sunday night. GK

&&

.HYDROLOGY...
A FLOOD WARNING is now in effect for the Teton River near Driggs
as small streams/creeks and the main stem river continue to run
high. Minor flooding is in the forecast starting tonight on the
main stem river and is expected to remain at that level through
much of next week, aided by additional snowmelt from the Tetons
and Big Holes. Further downstream along the Teton River near St.
Anthony, that gage is also nearing action stage and is forecast to
reach that tonight and remain elevated into next week.

Several other rivers across the CNTRL Mountains are also seeing
diurnal increases with the Big Lost River at Howell Ranch
currently hovering around action stage. Along the Snake River,
increased flows out of Palisades Reservoir has also led to the
Snake River near Heise gage climbing up to action stage and it is
expected to stay there for at least the next week. MacKay

&&

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

&&

$$