Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 031132

Area Forecast Discussion
National Weather Service Spokane WA
432 AM PDT Mon Aug 3 2020

Temperatures will cool a bit today in the wake of a Pacific front,
but the weather will quickly warm back up on Tuesday and
Wednesday. A much stronger cold front will blast through the area
on Thursday. This will bring strong winds along with a threat of
showers and thunderstorms. Friday will be rather cool with many
locations staying below 80 degrees. The weekend looks mild and


Today:  A cold front racing through the state this morning is
bringing a few clouds to our area and is clearly seen on GOES
satellite imagery.  As this cold front moves through, an isolated
sprinkle or two is possible but that will be the extent of
precipitation as the atmosphere is still very dry.  Cooler air
moving in behind this front will drop daytime temperatures today
with highs 3 to 5 degrees cooler than what was observed on
Sunday. It will still be a bit breezy in the lee of the Cascades
today while minimum RH values bottom out between 20 and 25
percent. This will translate to elevated fire weather conditions
but the threat will quickly diminish after sunset.

Tuesday and Wednesday: Upper level ridging will gradually build over
the Pacific Northwest pushing up 850 mb temperatures and
subsequently surface daytime temperatures. Each day, locations will
warm a few degrees with highs topping out in the 90s for many
lower elevations by Wednesday. The lowest elevations in the
Columbia Basin will be approaching the century mark which may
cause issues for individuals sensitive to heat. Other than that,
clear skies and light winds will prevail as there will be little
in terms of synoptic forcing. Wilson

Wednesday night and Thursday: There is good agreement amongst the
models that a strong cold front will pass through the region
Thursday. The main concern with this front will be windy
conditions and potential for rapid fire spread. A secondary
concern will be potential for high based showers and isolated
thunderstorms Thursday morning ahead of the front then showers and
storms in the afternoon.

Winds: This will be one of the strongest cold fronts we have seen
this summer. The combination of a 13mb cross-CWA pressure
gradient and cold advection will support winds in the lee of the
Cascades and across the Columbia Basin on the order of 15 to 25
mph sustained with potential for some areas to be close to 30 mph.
Accompanying gusts of 30-45 mph will be possible, especially
within the Wenatchee River Valley and Waterville Plateau. In our
non-windy locations such as the mountain valleys, gusts will be
more infrequent but still on the order of 15-25 mph. Humidity
levels will not be extremely low but should dip into the 20-25%
range so any new fire starts could grow rapidly. Temperatures on
Thursday will be cooling back into the 80s.

Showers and Thunderstorms:  There has been an upward trend with
the potential for high based showers Thursday morning ahead of
the cold front on the NAM/GFS/EC. My confidence is low for
lightning strikes but something we will be watching closely in the
coming days. This morning activity will be associated with high
cloud bases near 10K feet so I would not expect much in the way of
precipitation outside a few spotty hundredths. This activity is
expected to track south to north across the the Eastern third of
WA and possibly across the border into North Idaho Thursday
morning. In the afternoon, a stronger wave will swing into the
region with a slight negative tilt. As a result, additional
showers and thunderstorms will be possible across the Northern
mountains and possibly some areas of the Okanogan and Methow
Valleys. These will have the potential to be a bit more intense
with gusty winds, small hail, and brief downpours. Lightning
strikes will also be a concern for potential new fire starts.

Thursday night through Monday: Much cooler weather is expected
for Friday into the start of the weekend as we hold on to a baggy
trough over the Northwestern US. Many ensemble suites support
afternoon highs in the 70s to lower 80s during this time and this
is now reflected in the latest National Blend of Models. High
temperatures on Friday will be roughly 10 degrees below average.
Overnight lows will provide natural air conditioning with readings
expected to dip into the 40s to 50s. Dry air moving into the
region Thursday night will promote dry conditions for Friday then
a small threat for showers will return to the northern mountains
for Saturday. There is a lot of spread in the models for Saturday
night through Monday with the evolution of the upper-levels. Some
models hang on to deeper troughing over the region and cooler,
showery weather; otherwise start to build in flat ridging
suggesting a subtle warming and drying trend. Forecast leans
toward the latter of these solutions but would not rule out some
changes as we continue to iron this out. Big picture would suggest
no big warm-ups, potentially locally breezy winds, and high
uncertainty with any precipitation chances. /sb


06Z TAFS: A band of high clouds moving through this morning is
associated with a weak cold front. This is not expected to produce
any precipitation but will continue the westerly flow at TAF
sites. Late afternoon/evening gustiness is again likely at EAT
while VFR conditions continue through the TAF period. Wilson


Spokane        87  56  89  57  94  60 /   0   0   0   0   0  20
Coeur d`Alene  84  55  87  56  91  60 /   0   0   0   0   0  10
Pullman        82  52  86  53  91  57 /   0   0   0   0   0  20
Lewiston       89  62  92  62  97  67 /   0   0   0   0   0  10
Colville       89  51  91  52  94  55 /   0   0   0   0   0  10
Sandpoint      83  54  86  54  89  57 /   0   0   0   0   0   0
Kellogg        80  59  84  59  89  63 /   0   0   0   0   0   0
Moses Lake     91  56  92  58  97  61 /   0   0   0   0   0  10
Wenatchee      88  62  92  66  96  65 /   0   0   0   0   0  10
Omak           89  60  93  63  96  63 /   0   0   0   0   0  10




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