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000
FXUS66 KOTX 271203
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
503 AM PDT Tue Oct 27 2020

.SYNOPSIS...
Temperatures will begin to moderate this week with near average
readings by the end of the week. Significant precipitation is not
expected this week. An incoming system increases chances for
light rain and mountain snow for the end of the week.

&&

.DISCUSSION...
Today through Thursday night: The Inland Northwest will be on the
edge of a building high pressure ridge in the eastern Pacific.
Moisture streaming over BC will make this a dirty ridge in the
sense that mid to high level clouds will filter across at times
through Wednesday. A ripple through the westerly flow across
western Canada will draw in a bit more moisture into the Northeast
Mountains and Northern Panhandle for Wednesday. The atmospheric
column is expected to moisten just enough for some flurries in the
morning to sprinkles by the afternoon for places like Metaline
Falls, Sandpoint and Bonners Ferry. Cloud cover will be a bit
thicker across these northern zones on Wednesday as well and
remain clear or mostly clear further south into the basin and over
to the Palouse, Lewiston-Clarkston Valley and Camas Prairie. The
clear skies at night will strengthen nighttime inversions, and,
even though there will be some sun in the afternoon, warming
temperatures aloft around the ridge will make it tough to break
these inversions to achieve as much warming as models are
suggesting. The strong inversions will result in stagnant
conditions. Conditions may not be as stagnant into Wednesday
though with the clouds, but little in the way of mixing is likely
region-wide Wednesday night through Friday morning.

Fog is expected to increase through this week as dew points see a
steady increase with surface moisture mixing into the boundary
layer. This will be especially so where snow is on the ground
across the northern mountain valleys and down into the Spokane-
Coeur d`Alene corridor. Thursday looks like the best chance for
fog this week with the best potential for clear skies, a moist
boundary layer and weak winds. Temperatures will also modify
through the week with lows in the 20s and highs in the 40s to low
50s for most places by mid week. /SVH

Friday through Monday: The upper level ridge begins to break down
on Friday as a trough and its associated cold front begin to push
into the Pacific Northwest Friday afternoon. The front isn`t too
impressive and has been becoming less impressive with each new
model run. Temperature wise, highs slightly drop this weekend
compared to Friday, but remain in the low to mid 50s. Snow levels
are expected to be above 5000ft keeping rain and snow chances
limited to the higher mountainous regions with little to no
precipitation expected for lower lying areas. However, increasing
cloud coverage will keep low temperatures quite moderate compared
to the cold temperatures we have experience the past few days.
Southwest winds will pick up following the front on Friday and
will be breezy mainly for the Columbia Basin into the Palouse with
gusts up to 20 mph during the afternoon and evening hours.

After the trough exits the area early Saturday morning, the ridge
returns putting the PNW into a primarily W-NW flow through the
weekend into early next week. Skies will partly to mostly cloudy,
and temperatures will be normal for late October/early November
with highs in the 50s and lows in the 30s. VMT

&&

.AVIATION...
12Z TAFs: A little bit of valley stratus is expected this morning
in northeast Washington and in the central to northern Idaho
Panhandle. This will include a scattered stratus deck from KGEG
to KCOE and up the Silver Valley in Idaho. Ceilings will be above
3 kft agl with VFR or, at times, marginal VFR conditions.
Otherwise, high cirrus will filter down into north-central and
northeast Washington and the Idaho Panhandle as moisture tops high
pressure in the eastern Pacific. Further south toward the Oregon
border will be clear to mostly clear skies today and tonight.
/SVH

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        36  22  44  25  48  29 /   0   0   0   0   0   0
Coeur d`Alene  35  24  43  29  49  31 /   0   0   0   0   0   0
Pullman        40  24  48  28  55  32 /   0   0   0   0   0   0
Lewiston       46  31  53  36  60  38 /   0   0   0   0   0   0
Colville       38  19  44  24  47  25 /   0   0   0   0   0   0
Sandpoint      36  25  42  29  45  30 /   0  10  10  10   0   0
Kellogg        39  30  47  35  50  38 /   0   0   0   0   0   0
Moses Lake     43  24  50  26  52  29 /   0   0   0   0   0   0
Wenatchee      44  36  50  36  52  38 /   0   0   0   0   0   0
Omak           40  30  48  33  50  33 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Air Stagnation Advisory until 11 AM PDT Thursday for Central
     Panhandle Mountains-Lewis and Southern Nez Perce Counties-
     Lewiston Area-Northern Panhandle.

WA...Air Stagnation Advisory until 11 AM PDT Friday for East Slopes
     Northern Cascades-Northeast Mountains-Okanogan Highlands-
     Okanogan Valley-Waterville Plateau-Wenatchee Area.


&&

$$