738
FXUS66 KOTX 061140
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
440 AM PDT Mon May 6 2024

.SYNOPSIS...
Expect cool, windy, and showery conditions for the start of the
work week as a trough of low pressure remains over the Inland NW.
Then a ridge of high pressure builds into the region, giving way
to warmer and drier weather by midweek that continues into the
weekend. Next weekend has the potential to deliver our warmest
temperatures of the spring so far.

&&

.DISCUSSION...
Today and Tonight: In the wake of the departing area of low
pressure, the band of rain shifts slowly east and exits eastern
WA early this morning and most of north ID by late morning. Gusty
drier westerly winds in central WA are expected to expand east and
become widespread across the Columbia Basin, Palouse, and West
Plains by afternoon. Anticipate wind gusts of 30 to 40 mph. The
Inland NW will be under the influence of a broad upper level
trough today. With cooling aloft, instability increases with
surface based capes from 100 to 300 J/kg from southeast WA into
north ID. This would support a 10-15% chance of thunderstorms
embedded in the showers. With the windy synoptic winds, any
thunderstorm downdrafts could have locally higher gusts. Small
hail and occasional lightning would be additional concerns along
with brief downpours. The Storm Prediction Center highlights the
best chances for convection across the Palouse, LC Valley and
Camas Prairie this afternoon and evening. Snow levels near 4K ft
would support snow showers in the higher mountains passes,
especially Stevens and Lookout Passes although the metro model
suggests that road temperatures may limit snow accumulations on
the road surfaces. It will be a cool day with daytime highs
topping out in the 50s to lower 60s. The showers decrease in the
evening, although gusty winds continue in the lee of the Cascades
and Palouse. Overnight lows dip into the mid 30s to lower 40s.
Pockets of frost will be limited and mainly in sheltered northern
valleys where the growing season is slower to start.

Tuesday and Tuesday night: Anticipate subtle changes. The upper
level trough shifts east as a ridge of high pressure builds in the
eastern Pacific. This sets up a drier northerly flow across
central WA. The cooler temperatures aloft support diurnal
convection and lingering moisture nudged eastward into north
Idaho with the threat of rain and mountain snow showers.
Thunderstorm chances will be minimal (less than 5%) with merely a
stray lightning strike possible. It will be another windy day,
although the direction shifts to northwest to north which enhances
stronger gusts down the Okanogan Valley, across the Waterville
Plateau and Columbia Basin with gusts of 30 to 40 mph. It will be
drier as well with a decrease of cloud cover. Daytime temperatures
look to be a couple degrees higher than Monday, although still
cool for early May. /rfox.

Wednesday through Sunday: Ensembles remain in agreement as far as
advertising a dry ridging pattern with a warming trend through this
period. An exception will be over portions of North Idaho where some
minor chances of precipitation linger Wednesday, otherwise
positively tilted flopover ridging shows amplification and
orientation to favor surface winds from the north and northeast
starting Wednesday night and continuing on into about Friday. After
Friday the ridge looks like it flattens out some as disturbances
overtop it, however their only impacts will be limited to allowing
the surface winds to fluctuate a bit more in direction and intensity
over the weekend.
/Pelatti

.HYDROLOGY...
The unseasonably warm temperatures this weekend will increase the
high mountain snowmelt in the northern Cascades, Selkirks, and
northern Panhandle mountains. This will give way to rises in flows
on the creeks and rivers in the east slopes of the Cascades,
Okanogan Highlands to the northern ID Panhandle. Due to the lower
mountain snowpack, the additional rises should bring streamflows
to normal levels. A few river basins may near bankfull conditions,
although the threat of river flooding remains very low (less than
10%) across the Inland NW. /rfox.

&&

.AVIATION...
12Z TAFS: A band of rain is expected to exit the KGEG-KCOE area
this morning and retreat from north ID by midday. Afternoon
instability will increase the chance for widely scattered showers
across eastern WA and north Idaho into the early evening hours.
There is a 30% chance for MVFR conditions with heavy showers and a
less than 15% of thunderstorms especially across southeast WA into
the southern ID Panhandle. Expect widepsread westerly wind gusts
in the range of 20-30 kts. /rfox.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Confidence is low on MVFR conditions with the low cloud deck in
the wake of the rain band and with the heavier showers this
afternoon across extreme eastern WA and north ID. Confidence is
high for VFR conditions across central WA. /rfox.

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

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        57  35  59  37  64  39 /  40  10  10   0   0   0
Coeur d`Alene  53  35  56  37  59  39 /  70  30  20  10  10   0
Pullman        52  34  52  35  56  37 /  40  20  10   0  10   0
Lewiston       60  40  60  41  62  42 /  40  20  10   0  10   0
Colville       59  34  60  36  68  37 /  60  20  10   0   0   0
Sandpoint      52  36  53  38  58  40 /  90  30  30  20  20   0
Kellogg        49  35  49  37  55  40 /  90  50  50  20  20   0
Moses Lake     62  38  64  37  70  41 /  10  10   0   0   0   0
Wenatchee      59  40  59  40  69  46 /  10   0   0   0   0   0
Omak           64  36  66  38  72  44 /  10  10   0   0   0   0

&&

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

$$