645
FXUS66 KOTX 300345
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
845 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...
00Z TAFS: A weather system passing through into the early evening
will continue to promote scattered showers and gusty west winds.
Heavier showers will continue to produce small hail or graupel
along with an isolated lightning strike. This evening with the
loss of daytime heating shower will dissipate along with the gusty
winds. 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. Mainly VFR
conditions are expected, except for KPUW/KCOE from near 12-18z
Tuesday with the HREF showing near a 60% chance of MVFR
conditions.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
There is about a 30% chance of blowing dust across the Columbia
Basin into the early evening, including at MWH. Confidence in
visibility dropping below 7 miles is low so did not include
mention in TAF. Confidence is also low that thunderstorms will
impact terminals through early this evening and also Tuesday
afternoon. 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 /  50  40  20  30  20  30
Lewiston       36  56  37  61  39  62 /  40  40  30  20  10  30
Colville       25  54  30  61  33  61 /  40  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 /  60  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.

&&

$$