357
FXUS66 KOTX 221855
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1155 AM PDT Wed May 22 2024

.SYNOPSIS...
Today will be cool with steady rain across far north Idaho and
northeast Washington. Scattered showers will occur across parts
of southeast Washington this afternoon. Thursday will feature
scattered afternoon showers and thunderstorms mainly north of
Spokane. Memorial Day weekend will be cool and showery Saturday
and Sunday followed by dry weather Monday with highs in the 70s.

&&

.DISCUSSION...

Rest of Today: Satellite imagery as of 11 AM showed the center of
our upper low near the Tri Cities. Bands of rain were wrapping
around the low continue to be focused across north Idaho and
northeast Washington.

Rainfall amounts with this system have been the highest along an
axis from Republic to Kettle Falls to Cusick where sensors report
between a half inch and an inch of rain since last night. For the
remainder of the afternoon into the early evening an additional
quarter to third of an inch is generated by the HREF along the
Canadian border from north central Washington into northwest
Montana with localized amounts up to a half inch in Bonner and
Boundary counties.

A 10 to 20 percent chance of lightning has been added to the Moses
Lake, Ritzville, Washtucna, and Pomeroy areas this afternoon under
the heart of the upper low. Breaks in the cloud cover in the
Columbia Basin should generate the best low level instability
across the region, and this is where the GFS and HREF generate up
to 200 J/Kg of surface based CAPE. Any thunderstorms should be
short-lived due to marginal instability and shear.

Winds have been increased early in the afternoon to 15 to 25 mph
from Wenatchee to Moses Lake to Pullman in response to surface
pressure falls in eastern Washington under the upper low. As the
upper low dives southeast into Oregon and southern Idaho this
evening, winds will relax and remnants of the deformation band
near the Canadian border sink south producing additional light
rain through the night over the Idaho Panhandle, Palouse, and
Camas Prairie. /GKoch

&&

.AVIATION...
18Z TAFS: The most persistent band of rain with ceilings of
2500-3500ft will pivot north of Coeur d`Alene and Deer Park this
afternoon and stall around Sandpoint, Bonners Ferry, and Colville.
Overnight, remnants of this band of rain will sink southward as
the upper low sinks into Oregon and southern Idaho bringing
another shot of light rain to Coeur d`Alene, Spokane, Pullman, and
Lewiston. Boundary layer moisture from today`s rain will likely
result in 1500-2500ft ceilings across southeast Washington and the
southern/central Idaho Panhandle where the HREF gives Pullman an
80 percent chance 2000ft ceilings between 12-18z.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
HREF probabilities for 2000-3000ft ceilings at Coeur d`Alene and
Spokane are than 20 percent Thursday morning. There will be a good
deal of dry northerly winds in the mid and upper levels suggesting
clearing in the morning. Since GFS MOS produces a stratocumulus
deck at Coeur d`Alene, and NAM/GFS soundings support that idea a
BKN025 deck has been included. It wouldn`t be surprising to see
similar conditions at SFF and GEG, and may need to be added later
TAFs. /GKoch

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

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        54  40  64  45  68  46 /  20  20  30  10  20  20
Coeur d`Alene  49  40  60  45  67  45 /  50  40  40  20  30  30
Pullman        50  39  59  40  65  44 /  10  30  10   0  20  40
Lewiston       59  47  66  46  73  51 /  10  40  10   0  20  40
Colville       50  35  64  39  67  41 /  90  40  70  60  50  40
Sandpoint      49  38  58  44  64  44 /  90  70  60  50  50  40
Kellogg        46  42  57  45  64  47 /  70  70  40  20  40  50
Moses Lake     58  42  72  44  73  47 /  50  20   0   0  10  10
Wenatchee      58  47  71  47  71  49 /  50  20   0   0  10  10
Omak           58  43  72  45  72  46 /  80  50  30  10  20  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$