190
FXUS66 KOTX 300452
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
952 PM PDT Mon Apr 29 2024

.SYNOPSIS...
Scattered showers will continue into Tuesday. Winds will decrease
tonight with the potential for frost expanding across the mountain
valleys through Wednesday morning. A warming trend through the
rest of the week into the weekend. Weather conditions will remain
unsettled for the rest of the week with a weather system moving in
off of the eastern Pacific on Thursday and another one over the
weekend.

&&

.DISCUSSION...
Evening update: The mid level disturbance responsible for today`s
convection is beginning to shift out of the area with a couple
remaining bands of showers stretching from the Palouse and Camas
Prairie up towards Lookout Pass as of 830 PM. Radar was also
showing some showers up near Lauier and Northport. As this system
continues to push east shower activity will continue to be on the
decrease. The evening POP`s were adjusted based on radar trends. The
showers helped cool the lower level considerably this evening with
many areas across northeast Washington and the Idaho Panhandle
already down into the upper 30s to low 40s as of 8 PM. Expect
frost in many areas of Eastern Washington and north Idaho Tuesday
morning.

Another low pressure system near Vancouver Island will drop
southeast towards the south WA coast tonight. Bands of snow showers
will continue to rotate north into Stevens Pass tonight where a
Winter Weather Advisory remains in place through 2 AM PDT. The
focus of more persistent snow showers for the Cascades will shift
south of Stevens Pass Tuesday morning as the main energy from the
low slides into southern Washington and northern Oregon. JW

&&

.AVIATION...
06Z TAFS: Following the showers that went through the Idaho
Panhandle this evening is a moist boundary layer. Expect
increasing areas of MVFR stratus between 9-15z Tuesday over the
Idaho Panhandle and southeast Washington as light upslope winds
continue which includes KCOE/KPUW. Drier air in Central
Washington has spilled into the Spokane area which leads to a
better chance for conditions remaining VFR at KGEG/KSFF. On
Tuesday another round of showers will develop as the atmosphere
destabilizes but less in coverage compared to today. Isolated
thunderstorms may also develop, but the main threat will be over
the higher terrain of SE Washington (Blue Mountains), and up over
NE Washington around Republic and Colville.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
The HREF is showing near a 60% chance of MVFR stratus expanding
over the Palouse into the Idaho Panhandle overnight, but keeping
probability closer to 20% for KGEG/KSFF. There is high confidence
in continued VFR conditions in Central Washington due to a much
drier boundary layer. There is a 20% chance of thunderstorms on
Tuesday mainly across southern Washington into the Lewiston area,
and up over the mountains of NE Washington. Confidence is any of
the TAF sites being impacted is too low to include in the TAF
forecast. JW

-----------------------

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

For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https://www.weather.gov/otx/avndashboard

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        31  53  34  58  36  60 /   0  20  10  10  10  20
Coeur d`Alene  30  50  33  55  36  59 /  10  30  20  30  10  20
Pullman        31  48  32  53  34  57 /  20  40  20  30  20  30
Lewiston       36  56  37  61  39  62 /  20  40  30  20  10  30
Colville       25  54  30  61  33  61 /  10  40  10  20  10  30
Sandpoint      29  50  34  53  36  58 /  20  40  20  50  20  40
Kellogg        32  45  34  48  36  56 /  20  50  30  70  20  40
Moses Lake     34  59  34  66  38  62 /   0  10   0   0  10  20
Wenatchee      38  57  38  63  41  59 /  10  20   0   0  10  20
Omak           32  58  35  66  41  64 /   0  20   0   0  10  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Winter Weather Advisory until 2 AM PDT Tuesday for Western
     Chelan County.

&&

$$