Ammon, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

282
FXUS65 KPIH 301734
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1134 AM MDT Sun Mar 30 2025

.KEY MESSAGES...

- A brief ridge of high pressure today will bring a return to
  mostly dry conditions outside of isolated rain/snow showers in
  the mountains and across the Upper Snake River Plain.

- A warm front lifting north tonight into Monday morning will
  support another round of rain/snow showers with a cold front
  on Monday bringing widespread precipitation chances along with
  isolated to scattered thunderstorms.

- Winds will remain elevated, peaking on Monday and Tuesday.

- A secondary Pacific system building in midweek will keep
  precipitation chances going ahead of a ridge of high pressure
  building in by the weekend into early next week.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 237 AM MDT Sun Mar 30 2025

Early morning satellite imagery shows a departing 500 mb trough
working east over the Continental Divide as isolated to
scattered snow showers continue in the mountains and across the
Upper Snake River Plain. As this system exits to the east,
predominant mostly dry conditions are expected by around midday
regionwide as a brief ridge of high pressure shifts overhead.
Given clearing skies in between systems, we have begun to see
some areas of low stratus develop which may lead to patchy dense
fog at times before these low clouds burn off later today. This
relative break in precipitation will remain short in nature as
a warm front lifting north out of the Great Basin this afternoon
and evening will help reintroduce a mix of rain/snow showers
building in southwest to northeast through the overnight hours.
Looking towards Monday morning, a cold front will build in out
of the west and support more widespread rain/snow chances and
isolated to scattered thunderstorms. Precipitation may be
moderate to heavy at times associated with more organized cells
or lines with thunderstorms supporting gusty winds and small
hail at times. The latest HREF ensemble model shows ~100-400
J/kg of CAPE and 40-60 kts of 0-6 km shear with a 20-70% chance
of thunder regionwide, creating a conducive environment for
isolated stronger thunderstorm development. As this cold front
departs east late Monday, precipitation chances will persist
Monday night into Tuesday as a 500 mb low tracks directly over
southern Idaho.

Precipitation/SWE totals with this system have remained
consistent with previous guidance showing 0.25-0.50" across our
lower elevations and 0.50-1.00" in our higher elevations with
locally higher totals possible across highest elevations.
Translated to snow, we are looking at an elevation dependent
T-4" in the valleys and 4-12" in the mountains. Highest snow
totals are expected around the Sawtooth/northern Wood River
Valley region and east of I-15 into the higher terrain which is
where potential winter weather headlines will likely be needed
to capture snow impacts. This is where we are expecting 3-8" in
the valley and 6-14" in the mountains. Have held off on any
product issuance at this time in coordination with neighboring
WFOs but will pass this potential along to future shifts.

Temperatures Sunday into Monday will remain near to below
seasonal norms with highs in the 40s/50s and lows in the
20s/30s. Winds will also remain breezy both days with gusts
peaking Sunday around 25-35 mph and Monday around 30-45 mph.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 237 AM MDT Sun Mar 30 2025

Additional showers will occur on Tuesday with the 2nd round of
rain and snow. Gusty winds are expected especially for the Magic
Valley and South Hills/Albion Mountains. We are generally
expecting 6" or less for snow through Tuesday with the
exceptions of highest elevations of the Bear River Range,
Sawtooths and eastern highlands. Those areas should up to 16"
of snow. Lowest elevations will see mostly rain although a bit
of snow could mix in or change over a bit for brief
accumulations. Occasional showers are likely for Wednesday-
Friday as a rather disorganized pattern develops overhead. Any
precipitation amounts look to be light and sporadic in coverage.
A blocking pattern still appears in the offing for next
weekend, with the high pressure side of the pattern being almost
directly overhead. Temperatures drop a bit for Tuesday and
Wednesday, with very few (if any) spots hitting 50 for highs.
With high pressure returning, highs jump back into the 50 to mid
60s by next weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1117 AM MDT Sun Mar 30 2025

Satellite imagery shows cloud cover continuing to spread over
the region this morning. VFR conditions in place currently with
light winds. As we progress into the afternoon, and especially
overnight, clouds and precip will overspread the region with
mountain terminals of KSUN and KDIJ likely to see snow while
KIDA, KPIH and KBYI will be limited to rain. Still a bit of
uncertainty with respect to timing out the precip as hi-res
models show a range of different solutions. As such, continued
with more of a broadbrushed approach but did add a TEMPO for
KSUN where there appears to be a bit more of a consensus. Bottom
line, expect gradually deteriorating aviation conditions as we
get into the day Monday with lowering CIGs and precipitation at
all eastern Idaho terminals.

&&

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

&&

$$

SHORT TERM...MacKay
LONG TERM...Keyes
AVIATION...McKaughan