369
FXUS65 KPIH 011916
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
116 PM MDT Wed May 1 2024

.SHORT TERM...Tonight through Thursday night.
Freeze warnings have again been issued for lower elevations in the
Snake River Plain, Eastern Magic Valley and Arco/Mud Lake and
Shoshone Lava Beds. Expect widespread low temperatures below 30
degrees. Many mountain locations will be in the teens and lower
20s. Other impact short term will be isolated to scattered rain
and snow showers with snow levels near valley floors late this
afternoon and early evening before ending overnight. May see an
isolated thunderstorm as well. Winds expected to die down to well
under 10 mph by midnight as well. Another short wave will return
showers Thursday afternoon through Thursday night with snow levels
a bit higher than today in the 5 to 6 thousand foot range. Snow
amounts in the mountains are expected to remain very light this
afternoon and evening again on Thursday and Thursday night. Highs
Thursday in the 30s and 40s mountains and upper 40s to mid 50s
valleys so remaining well below seasonal normal for the first part
of May. Lows Thursday not as cold but still expect in low
elevations in the 25 to 35 range so may again need either freeze
warnings or frost advisories. Winds on Thursday will not be as
strong as today either staying mainly under 10 mph.
GK


.LONG TERM...Friday through next Wednesday.
Under the increasing influence of high pressure for Friday and early
Saturday as a broad trough which was situated over us midweek shifts
east, look for a return to dry conditions with highs in the 50s/60s
for Friday and 60s/70s for Saturday. Given Pocatello has not seen 70
since back on April 24th, the start of this weekend is shaping up to
the warmest weather we have seen in over a week but that will
quickly change later in the day Saturday heading into Sunday.

While models remain in solid agreement on this ridge feature
building in to round out the work week into Saturday, that
confidence also continues to support another H5 low dropping SE out
of the Gulf of Alaska around this similar timeframe. This storm
system is favored to move onshore from the Pacific Saturday into
Sunday with a return to isolated to scattered showers progressively
increasing in coverage throughout the day as a warm front lifts
north out of the Great Basin. This warm front will support strong
winds areawide around 15-30 mph with gusts up to 30-55 mph. WIND
ADVISORIES may need be need on Saturday especially further south but
will need to be monitored over the coming days with the latest GFS
and ECMWF models showing 700 mb winds around 40-50 kts across
extreme southern Idaho and to a lesser extent further north.

Rain and mountain snow showers will return areawide by Saturday
night into Sunday as this H5 low tracks through the NRN Great Basin
and SRN Idaho before ultimately shifting east heading into early
next week. Given overnight lows hovering around freezing to below
freezing for most, we may see rain mix in with snow at times in the
valleys but accumulations look to remain limited and mostly confined
to high elevation mountain valleys. Moist, zonal/NW flow behind this
exiting low will allow for temperatures to return to below normal
levels with highs back in the 40s/50s starting Sunday and continuing
through midweek next week. With cold temperatures at night,
additional frost/freeze products may be needed especially if clearer
skies develop. Winds will remain elevated each day Sunday through
Wednesday but at this time look to remain below WIND ADVISORY
criteria. MacKay


&&

.AVIATION...For the 18Z TAFS through 18Z Thursday.
Predominant VFR conditions continue across CNTRL and ERN Idaho as an
upper level trough passing through the NRN Rockies works to support
scattered rain/snow showers and strong winds across the Snake Plain
and Magic Valley. MVFR/IFR CIGS/VIS will be possible when snow
showers move on station with conditions improving regionwide
overnight tonight as dry conditions return. The HREF model
probability of thunder shows around a 10-20% chance of thunderstorms
outside of KBYI but have kept any mention out of the TAFs at this
time due to marginal instability. Winds at KPIH, KIDA, and KBYI will
peak at 15-25 kts with gusts to 25-35 kts while KSUN and KDIJ see
winds 8-15 kts with gusts to 15-20 kts ahead of winds subsiding
overnight tonight. As conditions remain dry overnight into Thursday
morning, look for a return to shower activity for Thursday afternoon
with less than 10% chance of thunderstorms.MacKay

&&

.HYDROLOGY...
Moderate flooding remains ongoing at the Portneuf River at
Pocatello with the level remaining above moderate stage and
forecast to do so through Thursday with it expected to drop below
moderate stage Friday. And minor flooding continuing for the
Portneuf River at Topaz where the gauge remains above flood stage
and will remain so for several days. New flood warnings have been
issued for the Blackfoot River near Shelley at Wolverine Canyon
where the river has gone above flood stage and also near Blackfoot
where the river may go above flood stage this week as well and is
currently at action stage nearing bankfull.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 2 AM to 9 AM MDT Thursday for IDZ051>055.

&&

$$