742
FXUS65 KPIH 062035
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
235 PM MDT Thu Jun 6 2024

.SHORT TERM...Today through Friday Night.
Early afternoon satellite imagery shows a broad H5 ridge in place
over the WRN CONUS as a H5 shortwave trough lifts NE out of
Nevada. This slow-moving shortwave is already leading to a mix of
scattered showers and isolated thunderstorms across ERN Oregon
and WRN Idaho with this activity expected to shift east later this
afternoon through tonight. As this trough works east across the
NRN Great Basin, precipitation chances will follow along with it
which will help to introduce isolated to scattered shower and
thunderstorm chances into Friday. The primary hazard with stronger
storms will center around strong outflow winds both today and
Friday with these storms capable of producing wind gusts in
excess of 40 mph, small hail, and moderate rain. The HREF
probability of sustained winds greater than 34 mph shows a 30-70%
chance across the Snake River Plain and Magic Valley south into
Utah today, dropping to a 30-50% chance outside the CNTRL
Mountains for Friday. The HREF ensemble max wind gusts are also
in that 40-50 mph+ range. While the majority of locations will
remain mostly dry over the next 48 hours, the latest HREF ensemble
48-hour mean shows best chances for accumulations around that
T-0.10" range with locally higher totals around 0.10-0.50" with
both ranges dependent on where storms track over.

Today will mark the warmest day so far of 2024 across CNTRL/ERN
Idaho as highs reach the upper 70s to near 90 degrees for our
lower elevations with temperatures expected to be just as warm for
Friday under the continued influence of high pressure overhead.
Overnight lows both tonight and Friday night will be in the
50s/60s with some of our colder, higher elevation valleys dropping
down into the 40s. Outside of any thunderstorm outflow winds,
synoptic winds will remain light regionwide, staying less than 20
mph through the weekend. MacKay

.LONG TERM...Saturday through next Thursday.
The warming trend will persist into the weekend, with Saturday
looking to be the warmest day of the year thus far more much of
the region as the high pressure ridge amplifies overhead. Daytime
highs will range the upper 70s to low 90s in our mid-elevations
and valleys and 60s to 70s in the mountains. A trough will move
onshore on Sunday with the associated cold front bringing
widespread precipitation chances both Sunday and Monday and
dropping temperatures by 5 to 10 degrees by Monday. There will be
ample dry air to overcome and looking at the progression of
ensemble precipitable water indicates that amounts will approach 1
inch before returning to around a half inch or less on Tuesday.
EPS total QPF for this timeframe is around a quarter of an inch or
less with localized higher amounts in the high terrain, while
GEFS indicates higher totals up to around three quarters of an
inch along our borders with UT/NV and MT/WY. Upper-level flow will
turn more zonal after that, resulting in breezier winds during
mid-to late next week. With a low pressure system moving onshore
into the southwest, models show minimal moisture lifting north and
potentially bringing isolated showers mostly to the high terrain.
Cropp

&&

.AVIATION...For the 18Z TAFS through 18Z Friday.
VFR conditions forecast with mostly clear skies during the first
part of the day. Cloud cover will overspread the region with
isolated to scattered showers and thunderstorms this afternoon and
evening. The HREF indicates a 30% to 50% chance of thunderstorms
at KBYI, 20% to 30% chance at KPIH and KSUN, 20% or less at KIDA,
and less than 10% at KDIJ. The HREF ensemble mean and ensemble max
wind gusts indicates that convective wind gusts could range 20 to
45 kts. Thunderstorm chances will be greater and more widespread
Friday afternoon and evening. Cropp

&&

.FIRE WEATHER...
Seasonably warm and mostly dry weather will continue through
Saturday as a series of passing troughs overtop a ridge of high
pressure help to introduce isolated to scattered thunderstorm
chances, peaking in coverage each afternoon and evening. Winds
will remain light outside of any thunderstorm outflows as synoptic
winds stay less than 20 mph regionwide through the weekend.
Changes are on the way however starting Sunday into Monday as a
more organized trough moves onshore from the Pacific, helping to
introduce widespread precipitation chances Sunday into early
Monday as winds increase for Monday and Tuesday. RHs will run on
the dry side each afternoon in the teens/20s with some slight
improvement expected on Sunday as those more widespread
precipitation chances move in. Behind that exiting trough for
early next week, dry and warm conditions will return. MacKay

&&

.HYDROLOGY...
A FLOOD WARNING continues for portions of southern Teton County
as small streams/creeks continue to run high. Minor flooding
continues to be observed, aided by additional snowmelt from the
Tetons and Big Holes that feed into these creeks and streams as
temperatures continue to warm over the next several days. The
Teton River is also running at an elevated level and is currently
forecast to hit action level tonight while reaching minor flood
level by Sunday into Monday. 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 is expected to stay there for at least the next
week. MacKay

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Flood Warning until 4 PM MDT Friday for IDZ065.

&&

$$