928
FXUS65 KPIH 280833
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
233 AM MDT Tue May 28 2024

.SHORT TERM...Today and Wednesday
Today will be the warmest day we`ve seen across eastern Idaho
since at least early October as 80s look to be commonplace for
daytime highs in the lower valleys. Higher terrain areas will see
70s so certainly quite warm with ample sunshine, at least through
mid-day. A strong mid/upper level shortwave will move east across
the Pacific NW later today and tonight and we`ll see showers and
storms return to the forecast for the afternoon and evening hours.
Moisture is limited but modest instability and dynamics could
allow for some stronger storms. Best chances of this look to be
across the central mountains and into northern Idaho and western
Montana where SPC has continued their Marginal Risk designation.
The thunderstorm potential is regionwide however so even areas
outside of the Marginal Risk area could see a strong to severe
storm with winds being the primary threat but hail is also
possible. A front will move through during the overnight keeping
at least a low-end PoP potential in the forecast during the
overnight.

The trough axis shifts east on Wednesday and the pressure gradient
looks to tighten over the region. Winds will increase around
daybreak Wed AM and will likely near or exceed Wind Advisory
thresholds across parts of the Snake Plain and Arco Desert so
headlines may be needed later today to account for that.
Temperatures will be noticeably cooler with 60s expected for most,
50s in the mountains, with precipiation chances lingering across the
eastern half of the CWA. Overnight lows Wed night into Thu will be
close to warranting a Frost Advisory perhaps in the Upper Snake and
Arco Desert but we`ll see. Let`s get through the warmer temps and
storms today first. McKaughan

.LONG TERM...Thu through Mon night.
There is still around 15 percent chance on Thu for a trough to
bring precipitation to the northern half of the forecast area.
Beyond Thu night, the solution clusters are all dry for eastern
Idaho. The only matter of contention is how strong the upper level
ridge axis and its location over the Fri-Mon night period. On
Sun, some upper level troughing is expected in the western states,
but the amplitude is weak unless the low is in the southern tier
of the west coast.

Thu is the coolest day during this period, in the aftermath of the
upper level trough that passes through the previous night. Expect
widespread afternoon highs in the upper 50s and 60s. Then the flow
changes to either zonal or a southerly component, allowing some fast
warming for temperatures up about 8 to 12 deg F on Fri. For the
upcoming weekend, there is a likely chance for southwesterly airflow
which would bring a strong warming trend. Expect 4 to 8 deg F from
Fri to Sat, with some return of 80+ deg F in the southwest corner
lower elevations. Cloud cover from the possible upper level trough
on Sun does bring a cooling trend, but unsure this will actually
happen. Warming for Mon means a return to some 80+ deg F highs,
again in the southwest corner of the forecast area. Overnight lows
are expected to be mild, with Thu night the only night where a Frost
Advisory is even a consideration; right now, it appears to be just
close.

Wind during the period is driven by the diurnal development of
vertical currents to bring gusty breezy to windy conditions mainly
in the Snake River plain and eastern Magic Valley. Expect this every
day during the afternoon and early evening. Messick

&&

.AVIATION...
VFR conditions expected through the forecast period outside of any
afternoon convective activity. Skies will be mostly clear early and
with light and variable winds. As we get into the afternoon, a
trough moving into the Pacific NW will help spark some showers and
thunderstorms. For now, will maintain VCTS regionwide to account for
this. Biggest forecast challenge later today will be trying to time
and specific tstm impacts at a terminal along with the potential for
gusty outflow winds. Winds look to increase just beyond the current
forecast period into Wed afternoon with gusts in the 30-40kt range
looking likely. McKaughan

&&

.FIRE WEATHER...
A couple of windy days for the BLM districts as a
trough approaches today and a cold front drives through Wed/Wed
night. This will trigger some thunderstorms, mainly dry, so outflows
could be strong, especially in the Salmon-Challis NF where there is
a marginal threat of gusts to 60 mph or more. This will be the
warmest day of the year so far, but the clouds and colder airmass
behind the cold front will drive afternoon highs down 12 to 20 deg F
from today on Wed. Wed afternoon winds should be very strong, with
areas in the Idaho Falls BLM District expected to see 30+ mph wind
in the afternoon and evening. The trough moves out quickly and
expect warmer and drier conditions for the rest of the week and into
the weekend. The warming and drying will be gradual through the
period as airflow is mostly westerly. Messick

&&

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

$$