Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 261145
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
445 AM PDT Mon Sep 26 2016

.SYNOPSIS...
A mild and mostly dry weather pattern is expected through
Wednesday. Temperatures will be above average, with several days
of highs in the mid 70s to mid 80s. Cold front passage on Tuesday
will produce breezy winds down the Okanogan Valley. A pattern
change is expected to arrive late in the week with chances for
showers beginning Thursday and continuing into the weekend. By
Saturday and Sunday, afternoon temperatures will likely be in the
60s.


&&

.DISCUSSION...
Today and Tuesday: Satellite imagery shows a low pressure trough
pushing across the Gulf of Alaska. This will nudge the high
pressure ridge axis into western MT. Warmer temperatures will be
pumped up into the region along the upstream portion of the ridge
axis with 850 mb temps climbing to between 17-21 Celsius. The
proximity of the incoming trough will also provide a bit better
momentum transfer and mixing in the boundary layer. This should
allow the warmer temperatures aloft to mix down to the surface
although not quite as efficiently as we would see during the
summer season. Still, we are in store for a warm day across the
Inland Northwest today with widespread high temperatures in the
80s. Warmest temperatures are expected across the southeast
portion of the region from the basin, over the Palouse and down
into the L-C Valley. These areas will be in the mid to upper 80s
with some locations topping out near 90 degrees. A few near record
high temperatures for today will be possible, but not expected to
be widespread.

A dry cold front will then arrive Tuesday morning. A marine push
will result in breezy winds through the Cascade gaps for the
morning on Monday. Then a tight northerly pressure gradient will
set up across the Okanogan Valley for the afternoon on Tuesday.
Winds are expected to be quite breezy through the Okanogan Valley
with gusts between 30-40 mph expected. The winds will bring down
drier air as well with a heightened fire weather concern in
receptive fuels. Temperatures will cool off a bit on Tuesday with
highs generally in the upper 70s to lower 80s. /SVH

A progressive weather pattern is setting up for the rest of the
week. Zonal flow will be over the region Tuesday night and
Wednesday behind the exiting cold front. The westerly flow will
then buckle Wednesday night and Thursday as the next up stream
deepens off the B.C. coast. Model guidance is very similar showing
this low deepening and finally cutting off from the steering flow
around about Friday. This puts the region in a moist southerly
flow and will open the door for rain showers and a few
thunderstorms.

Tuesday night through Wednesday night...the surface gradient will
increase and become northerly Tuesday night and Wednesday behind
the frontal passage. The main impact will be increasing winds down
north-south canyons and valley. The main area of concern will be
down the Okanogan and Methow valleys, and to a lesser extent down
lake Roosevelt and the Purcell Trench. Northerly winds of 10 to 20
mph with localized gusts 20 to 25 mph will be possible. Relative
humidity will be 20-30 percent. While no Fire Weather highlights
are expected a fire could make a good run in the grass and brush.
Temperatures will remain above normal with highs mainly in the 70s
to low 80s.

Thursday through Saturday...The upper level low will move slowly
towards the Pacific Northwest allowing the flow to shift to
southerly. Southerly flow will allow deeper moisture to work into
the region from the south. Increased moisture, combined with
several weak disturbances and afternoon heating will set the stage
for showers each afternoon, with a chance of thunderstorms Friday
afternoon. Temperatures will cool 5-7 degrees each day Thursday
through Saturday. Afternoon highs will only make it to the low to
mid 60s by Saturday. Tobin

Sunday and Monday: This period looks pretty wet as a series of
weaker short waves follow the exiting upper low. Each disturbance
has ample deep moisture available and typical mountainous areas
will have the best chance of rain, but even lowland areas could
see showers, especially on Monday. Temperatures will remain
slightly below normal in the upper 50s and low 60s. /bwilliams


&&

.AVIATION...
12Z TAFS: Passing high cirrus clouds above 25 kft is expected at
times today into Monday night ahead of an approaching shortwave
disturbance. Breezy easterly winds expected at KPUW through 18Z
with sustained speeds at 12-15 kts and gusts up to 20 kts. /SVH


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        83  55  79  53  79  51 /   0   0   0   0   0  10
Coeur d`Alene  85  53  78  52  80  51 /   0   0   0   0   0  10
Pullman        84  52  79  50  81  49 /   0   0   0   0   0  10
Lewiston       89  57  84  57  85  55 /   0   0   0   0   0  10
Colville       85  48  80  44  80  45 /   0   0  10   0   0  10
Sandpoint      77  47  75  45  73  47 /   0   0   0   0   0  10
Kellogg        79  49  76  51  79  49 /   0   0   0   0   0  10
Moses Lake     84  52  82  48  80  45 /   0   0   0   0   0  10
Wenatchee      84  59  79  51  78  50 /   0   0   0   0   0  10
Omak           83  53  78  47  78  47 /   0   0  10   0   0  10

&&

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

$$


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