385
FXUS66 KOTX 092246
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
346 PM PDT Sun Mar 9 2025

.SYNOPSIS...
Gusty southwest winds are expected into early Monday morning.
Cooler and more active weather will return for the middle of the
week and persist into next weekend with several rounds of mountain
snow, and a mix of rain and snow in the valleys.

&&

.DISCUSSION...

Today through Tuesday: A dynamic system will bring a period of
heavy mountain snow to the Cascades this evening, strong winds to
the Columbia Basin, Palouse, ID Panhandle this evening and
tonight, and cooler temperatures tomorrow thanks to a strong cold
front passage.

- Winds tonight: Southwest winds are starting to pick up this afternoon
  as lee cyclogenesis occurs in southwest Alberta. The lowest
  analyzed pressure of 1001.4 mb as of 1 PM Pacific time is at the
  Claresholm, AB weather station which is about 250 miles
  northeast of Spokane which has a pressure of 1014.3 mb. The low
  will deepen to around 996 mb this evening before ejecting into
  the northern plains and winds will further increase southwest
  winds in central and eastern Washington/ID Panhandle. Wind gusts
  around 35 to 45 mph will peak around 10 pm to 2 am tonight
  before a frontally forced stratiform rain band moves through and
  stabilizes the mixed layer. Winds are stronger in the 2-4kft
  layer around 50 to 70 mph but a stable layer appears to prevent
  wind advisory worthy gusts from materializing at the surface for
  an extended period of time. Prefrontal showers may bring an
  increased chance of mixing down strong winds around 50 mph this
  evening particularly in the Palouse. Pressure gradients relax
  late tonight as the low ejects into the northern plains and wind
  gusts will mostly fall below 20 mph by the morning hours
  Monday.

- Snow tonight: A moisture plume over northwest Washington will
  slide southeast over the next couple hours and bring a period of
  heavy snow to the Cascades around 5 to 10 PM and slowly
  tapering off overnight thanks to the drier air behind the cold
  front. Stevens Pass has a 70% chance of 8+ of snow from 4 PM
  Sun to 4 AM Monday, but a 0% chance of 12+. A period of
  moderate snow is also expected at Lookout Pass around 2 AM to 5
  AM Monday as the moisture plume continues to move southeast.
  There is a 50% chance of 3 or less at Lookout Pass overnight.

A brief period of drying is expected Monday as rain moves out of
the region but precip chances return overnight into Tuesday as
another trough starts to dig south towards California. High
temperatures will only reach into the 40s and 50s behind the cold
front passage tonight. A surface low pressure will approach the
Vancouver Island area sending some warm frontally forced precip to
the INW Tuesday. Light snow is expected generally above 3500 feet
with this next system.

Chance of 3+ of snow 5 AM Tuesday - 5 AM Wednesday:
Stevens Pass: 45%
Sherman Pass: 30%
Lookout Pass: 10% /DB

Wednesday through Sunday: An enlonged upper trough off the coast
on Wednesday will provide a moist south-southwesterly flow over
the region result in a mainly valley rain and mountain snow
scenario. Given the stratiform nature of the precipitation and
somewhat mild 850mb temps ranging from near 0C near the Cascades
to 2-3C along the ID/MT border the main area of concern for pass
impacts include Stevens, and Sherman Passes. Currently the NBM is
showing near a 30-40% chance of 6" or more Wednesday through
Thursday morning for these passes. On Thursday as the trough axis
moves inland the air mass will turn more showery, with snow levels
falling to near 2000-2500 feet. Additional weather systems pass
through heading into next weekend with a better chance of valley
snow during the overnight and morning hours, especially above
1500-2000 feet. But with afternoon highs in the low to mid 40s
anything that does fall is not likely to stick around for very
long. The mountains will see additional snow accumulations with
the NBM carrying a 90% chance of at least 8" next weekend, with a
50% chance of similar amounts for Lookout Pass. JW

&&

.AVIATION...
00Z TAFS: VFR conditions will prevail. Increasing SW winds this
evening for KGEG-KSFF-KPUW-KMWH-KCOE as pressure gradients
increase in response to a deepening surface low pressure in
southwest Alberta. Prefrontal showers around 4-10z may mix down
40+ kt winds at KPUW-KLWS breifly. A stratiform rain band will
form as the front passes (6-15z) and stabilize the atmosphere
decreasing winds overnight into Monday.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence in VFR conditions.

-----------------------
Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        34  48  34  47  37  49 /  40   0  10  30  50  80
Coeur d`Alene  33  48  31  46  35  47 /  60  10  10  30  60  80
Pullman        36  46  35  46  37  46 /  60  50  20  30  50  80
Lewiston       42  52  39  53  40  53 /  30  30  20  20  40  70
Colville       29  49  29  45  33  46 /  20   0  10  30  60  80
Sandpoint      33  47  31  43  35  45 /  80  10  20  50  80  90
Kellogg        35  43  33  43  38  44 /  80  40  20  50  60  90
Moses Lake     33  53  34  50  37  53 /  10   0   0  10  20  40
Wenatchee      34  50  34  48  34  50 /  20   0   0  10  20  40
Omak           30  50  30  46  34  50 /  20   0   0  20  30  50

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Winter Weather Advisory until 5 AM PDT Monday for Western Chelan
     County.

&&

$$