Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 252336

Area Forecast Discussion
National Weather Service Spokane WA
336 PM PST SUN JAN 25 2015

Fog and low clouds will persist across portions of central
Washington and north Idaho. Record high temperatures will once
again be possible Monday across southeast Washington and the Idaho
Panhandle. A weak storm system will affect the area Tuesday and
Tuesday night bringing a small chance of precipitation to the
Cascades and cooler temperatures everywhere. A ridge of high
pressure will then rebound late in the week for drier weather and
more fog.


Tonight through Tuesday: Upper level ridge remains in place with
heights starting to decrease Monday through Tuesday as a weak
weather system flattens the ridge on Tuesday. The main forecast
challenge remains the low clouds and fog plaguing most of central
Washington through the north ID Panhandle. Believe the low clouds
and fog will continue through the night and starting tomorrow
morning will begin to break up as models show boundary layer
relative humidities decreasing a bit as southeast winds prevail.
There will be some locations that may not break out and those
include but are not limited to portions of the Okanogan valley,
Waterville Plateau and some spots north of Moses Lake. The wind
direction has switched to the north at the Spokane airport and are
hoping that it will not bring the fog that has stuck around north
Spokane and up toward Deer Park back into the Airport and
locations further south. Model guidance shows winds remaining from
the north all night, but boundary layer rh and winds show a dryer
southeasterly gradient that would keep the fog out. What will win?
We hope the later with no fog and sunny skies for our Monday
morning commute, but unfortunately cannot rule out the more
dreary option. The low clouds and fog problems will continue
Monday into Tuesday. Temperatures Monday will be above average
with several southeast WA and north ID locations approaching
record highs again. By Tuesday mid and high level clouds will
increase ahead of the weak weather feature moving onto the west
coast. The best chance of precipitation through the day will be
just right along the crest of the Cascades. /Nisbet

Tuesday night through Friday...The ridge which has been the
dominant weather of the past few days will likely persist with
just one minor hiccup to interrupt its presence. That minor
disturbance will be in the form of a rapidly weakening shortwave
trough which is expected to hit the northern Cascades by Tuesday
afternoon and slowly meander into the Idaho Panhandle overnight.
While the models have been consistent with the track of this
feature and its weakening trend they differ on how much moisture
it will carry. Model cross section suggest that most of the
moisture with this feature will be fairly elevated and will lack
sufficient ascent for widespread precipitation. Looks like the
only areas that can count on measurable precipitation will occur
near the Cascade Crest with a smaller chance over the Idaho
Panhandle. Snow levels will remain high enough that the main
precipitation threat will be valley rain and mountain snow.
Precipitation amounts if any should be quite light. Once this
feature moves through the ridge will begin to steadily rebound
however temperatures will be cooler than what we experienced today
and on Monday. Weak northwest flow could perpetuate the shower
chances in the Panhandle for another day...but its not a great
chance. Temperature forecasts will remain quite difficult as much
will depend on where fog forms and how long it persists. Model
soundings continue to suggest the best chances for fog will occur
over the northern valleys and near the Cascades and that`s where
we`d expect to see the coolest temperatures. fx

Saturday through Monday: The ridge that has been in place for the
past few days will begin to weak and flatten. The models do not
have good agreement on the timing. The GFS is bringing in the next
system early Sunday. The ECMWF is holding off bringing it in until
Monday. With this big discrepancy, the chance of precip was
increased slightly across the region bringing precip to the
mountain areas of the Inland Northwest. The Columbia Basin will
remain fairly dry with patchy fog expected in the mornings. The
model inconsistencies put little confidence into period.
Temperatures are expected to a few degrees above normal with highs
around upper 30s to low 40s. The lows will be upper 20s to low
30s. /JDC


00Z TAFS: VFR conditions expected at all eastern TAF sites with
the exception of some patchy fog between 06Z to 16Z for the
Spokane area. The main concern will be the stratus and fog banked
into the Basin and Wenatchee area creating LIFR conditions or
worse. They may improve to IFR conditions aft 20Z. There still
are pockets of LIFR vsbys generally north of Spokane where
snowmelt from warm temps has significantly contributed to the fog
threat. This includes the Deer Park airport. /JDC


Spokane        34  47  34  43  32  39 /   0   0   0   0  10  10
Coeur d`Alene  35  50  33  45  33  40 /   0   0   0   0  10  10
Pullman        40  54  40  49  36  46 /   0   0   0   0  10  10
Lewiston       41  58  39  52  39  50 /   0   0   0   0  10  20
Colville       33  41  26  38  31  38 /   0   0   0   0  10  10
Sandpoint      33  46  30  43  32  41 /   0   0   0   0  10  10
Kellogg        39  51  32  47  34  41 /   0   0   0   0  20  20
Moses Lake     34  45  34  43  31  40 /  10  10  10   0   0  10
Wenatchee      33  44  33  44  33  40 /  10  10  10   0  10  10
Omak           34  41  31  40  31  39 /  10  10  10   0  10   0



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