Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 261804
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1104 AM PDT Tue Sep 26 2017

.SYNOPSIS...
Drier and warmer weather will return to the Inland Northwest today
through Friday under mild high pressure. Thursday will feel a bit
like summer with afternoon temperatures in the upper 70s to low
80s. Temperatures will fall dramatically Friday night into
Saturday with the arrival of a strong cold front. The weekend will
be chilly, breezy, and showery.

&&

.DISCUSSION...


Today through Wednesday night: Positively tilted ridge shows
amplification and transition to a more neutral north to south non
tilt through this interval. This amplification and reorientation of
the ridge axis should push the path for any clutter of moisture
and/or disturbances fluxing through it further away to the north and
thus result in not only a dry forecast but one with not much in the
way of significant cloud cover. Forecast temperatures on the warm
side of what would be considered normal for this time of year.
/Pelatti

Thursday and Friday: Little has changed regarding the forecast for
Thu and Fri. Afternoon temperatures on Thu will climb into the
upper 70s to low 80s under clear skies. On Fri high clouds will be
on the increase in the afternoon ahead of an approaching cold
front. There may be enough cloud cover to hinder warming in
central Washington and highs for places like Wenatchee, Omak, and
Chelan have been lowered a couple of degrees into the mid 70s.
Prefrontal south winds will also increase Fri afternoon across the
Columbia Basin and open wheat country of the Palouse and West
Plains. Look for 10 to 15 mph with late day gusts up to 20 mph.

Friday Night through Sunday: The forecast for the weekend has been
changed considerably. Precipitation chances have been increased
Fri night through Sun. The evening models have trended deeper,
wetter, and cooler.

The most significant swath of rain will likely occur Sat morning
along the cold front. The central and southern Idaho Panhandle
could receive a quarter inch of rain with localized amounts up to
a half inch. Behind the cold front, Saturday afternoon promises to
be cool, breezy, and showery. If the evening model runs verify, a
500mb cold pool (-21C to -25C) will track across Oregon and
Washington yielding showers with snow levels falling into the 5500
to 6500 ft range. Afternoon temperatures in the upper 50s to mid
60s will be accompanied by 10 to 20 mph winds with gusts up to 25
mph across the Columbia Basin, Palouse, and West Plains.

There may be fewer showers Sunday over central Washington as the
cold 500mb trough migrates into Montana, but the GFS and ECMWF
suggest wrap around rain and high mountain snow for the Idaho
Panhandle and possibly the eastern third of Washington. Afternoon
temperatures will again be below average with more breezy west
winds.

Monday: The medium range models diverge into a mess of different
solutions by Mon and Tue. The ECMWF and Canadian share some
similarities early next week with the arrival of another wet
frontal system. The GFS trends drier with a cool northerly flow.
With little to hang our hat on, we kept a chance of showers in the
forecast with below average temps. /GKoch

&&

.AVIATION...
18Z TAFS: High pressure to remain anchored over the region through
the next few days providing mostly clear skies and light winds.
Patchy fog possible each morning in the river valleys...with
quick burn off each morning. Threat appears to low to add to KSFF
taf at this time. /sb

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        70  50  75  51  79  51 /   0   0   0   0   0   0
Coeur d`Alene  70  46  74  48  78  48 /   0   0   0   0   0   0
Pullman        69  46  75  48  78  49 /   0   0   0   0   0   0
Lewiston       75  50  78  52  81  52 /   0   0   0   0   0   0
Colville       73  44  78  45  82  46 /   0   0   0   0   0   0
Sandpoint      68  42  73  43  76  44 /   0   0   0   0   0   0
Kellogg        67  45  72  46  76  48 /   0   0   0   0   0   0
Moses Lake     76  47  80  48  82  48 /   0   0   0   0   0   0
Wenatchee      75  53  79  54  80  54 /   0   0   0   0   0   0
Omak           77  48  79  49  81  49 /   0   0   0   0   0   0

&&

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

&&

$$


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