Damaging Winds in Idaho, August 4, 2024

Area Forecast Discussion
National Weather Service Pocatello ID
252 AM MDT Sun Aug 4 2024

.SHORT TERM...Today and Monday.
Showers continue to shift north through the region overnight as a
weak shortwave lifts monsoon moisture through Idaho today. The
occasional lightning strike can't be ruled out, with the central
mountains the favored corridor, but chances generally remain less
than 20 percent for the first half of the day. Shower and
thunderstorm coverage will remain isolated during the day today as
activity shifts further east and tapers off by around 11 AM. CAMs
show redevelopment over the central mountains soon after with
isolated to scattered thunderstorms continuing through the early
evening before shifting northeast into Montana. HREF thunder
probability ranges 10 to 40 percent across the north-central
extent of our CWA, up to 70 percent along the MT Divide, and 20 to
40 percent along our border with WY. Outside of thunderstorm
gusts, elevated flow aloft will support breezy southwesterly
surface winds and 20 to 30 mph gusts across the Snake River Plain.
Sustained winds over American Falls Reservoir fall just below the
low-end threshold for a Lake Wind Advisory and therefore, we
won't be issuing any wind-related products for today. Expect up to
a 10 degree drop in daytime highs today as compared to
yesterday's. Temperatures will increase very slightly again
tomorrow as the ridge rebounds a bit following today's shortwave.
Another round of isolated to scattered showers and storms are
forecast tomorrow, with CAMs mixed on whether moisture will lift
into south-central Idaho late morning or early to mid-afternoon.
The strongest thunderstorms both today and tomorrow will be
capable of producing 40 to 50 mph outflow gusts and small hail,
with models predicting the strongest gusts today near the MT
Divide and tomorrow in Cassia County. As for smoke,
southwesterly/westerly flow aloft will continue to filter in
increased concentrations of smoke further east into the Snake
Plain and therefore, we continue to carry patchy smoke in the
forecast for the next two days. Cropp

.LONG TERM...Tuesday through Sunday.
Broad flat ridge of high pressure through the intermountain west
is shunted south early in the period as shortwave energy across
the PacNW shifts into the Northern Rockies. Flat flow aloft
Wednesday pushes most of the moisture out of East Idaho for
generally dry but breezy conditions. Ridge tries to redevelop
Thursday, but there is some ensemble support for another shortwave
trough driving into the region for Friday and Saturday, which
could return some showers/thunderstorms to the region. Otherwise,
expect cooler temperatures generally near seasonal normals, with
occasional breezy afternoon conditions. DMH

&&

.AVIATION...Shortwave will lift through the region today, with
isolated to scattered showers continuing through early evening.
Probability of thunder today is 10 to 20 percent at KSUN and 30 to
40 percent at KDIJ, with less than 10 percent chance at the
remaining terminals. That said, have forecast VCTS at the two
aforementioned terminals with VCSH elsewhere. Southwest winds will
increase beginning around 18z and remain breezy through the early
evening, with gusts 20 to 25 kts. Thunderstorms will also be
capable of producing 40 kt outflow winds, give or take. Otherwise,
we continue to forecast HZ/FU as increased concentrations of
smoke filter into eastern Idaho in southwesterly/westerly flow.
Cropp

&&

.FIRE WEATHER...Scattered showers and isolated thunderstorms early
this morning give way to increased thunderstorm coverage this
afternoon, especially across the Salmon-Challis NF and Targhee NF
areas. Gusty and erratic outflow winds in excess of 40 mph will be
possible. Most storms will have difficulty producing a wetting
rain, but that will be possible with stronger cells. Outside of
the storms, gusts are expected to reach around 20 mph especially
across the Snake Plain. A relative break in the pattern is
expected overnight, with another round of scattered showers and
isolated thunderstorms expected on Monday and Tuesday. Drier
conditions with more seasonable temperatures are expected later
this week, though breezy conditions will return as well. DMH

&&

.AIR QUALITY...Regional wildfires continue to impact air quality
over Southeast Idaho with increased concentrations of smoke
expected to filter into the region in southwesterly/westerly flow.
We continue to carry patchy smoke in the forecast over the next
two days, during which the Idaho DEQ is forecasting "Moderate" air
quality. Cropp

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 9 PM MDT this evening for
IDZ411-475-476.

&&