Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 220920
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
220 AM PDT Tue Aug 22 2017

.SYNOPSIS...
Today and Wednesday will be quite warm with afternoon
temperatures in the upper 80s to upper 90s. A strong cold front
will bring a threat for thunderstorms Wednesday night into
early Thursday, mainly over southeastern Washington and the
southern Idaho Panhandle. This will be followed by gusty westerly
winds Thursday. After a cooler Thursday and Friday, temperatures
will rebound back into the 90s early next week.

&&

.DISCUSSION...
Today through Wednesday night: An upper ridge will begin to shift
east today with warm southwest flow and mostly clear skies over
the area. This will allow high temperatures to warm into mostly
the 90s...and will be the warmest day of the week. On Wednesday an
upper trough approaches the coast. Southwest flow continues but
some increase in mid level clouds should bring slight cooling to
the area. Wednesday night as the approaching trough axis nears the
coast...an axis of mid level moisture and instability ahead of it
gets drawn northeast out of Oregon into SE Washington...Lewiston
area...and Central Panhandle Mountains. Models show only marginal
instabiltiy for thunder...so only isolated coverage is expected if
any lightning occurs at all.

Concerning smoke...visible satellite showed an extensive smoke
layer over western Oregon prior to sunset yesterday. HRRR smoke
model shows this smoke getting picked up into the mid level
southwest flow bringing increasingly hazy skies to the
region...beginning over south Central Washington this morning
before spreading north towards the Canadian border tonight. As
850-700mb winds turn more westerly on Wednesday into Wednesday
night should see much of the Oregon smoke push east and out of
the area except for possibly SE Washington. Although local fires
in the WA Cascades as well as Bridge Creek could still provide
some smoke to portions of the Inland NW. JW

Thursday through Monday: The computer forecasts continue to back
off on the strength of the weather system for Thursday. The cold
front is still progged to move through the area on Wednesday
night, but the upper level system just isn`t as strong or as far
south as previous forecasts. The result is a breezy Thursday, but
probably not strong enough to warrant fire weather highlights,
except for perhaps some local areas. All that said, it`s still
going to be very dry, with humidity levels down below 20% in the
afternoon. And temperatures will also be a tad warmer than
previously thought. So the combination of wind, RH and temperature
will yield potentially critical fire weather conditions, but
probably not enough to warrant warnings. But things could still
trend back the other way so stay tuned.

After the passage of that system, Friday will be the coolest day
of the week. Then the question becomes: how hot will it get next
week? By Sunday all computer forecasts have a strong upper level
high pressure over the Great Basin, extending northward into
southwest Canada. The computers vary a bit on just how hot it will
get. The ECMWF is the hottest, the GFS a tad cooler, and the
Canadian the coolest with the ridge displaced farther to our east.
Widespread 90s look like a safe bet at this point, with some
triple digits possible. But it`s getting very late in the year for
that kind of heat.  RJ

&&

.AVIATION...
06Z TAFS: VFR conditions are expected through 06z Wednesday. Very
few clouds are expected under a broad high pressure ridge. Mid and
high level smoke from central Oregon will likely overspread
southern Washington and the Idaho Panhandle on Tuesday. At this
time, it looks like the smoke will remain aloft. However, there
may be some visibility reductions late in the day Tuesday or into
Tuesday night around Lewiston and Pullman as smoke moves up and
down the atmospheric column. /GKoch

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        91  63  87  62  80  50 /   0   0   0  10  10   0
Coeur d`Alene  91  57  88  59  80  47 /   0   0   0  20  10   0
Pullman        91  59  87  60  77  46 /   0   0  10  30  10   0
Lewiston       97  66  93  65  86  54 /   0  10  10  30  20   0
Colville       91  53  89  54  83  44 /   0   0  10  10   0   0
Sandpoint      89  49  87  56  79  41 /   0   0  10  20  10   0
Kellogg        89  55  86  58  76  47 /   0   0  10  30  40   0
Moses Lake     94  59  91  58  85  47 /   0   0   0   0   0   0
Wenatchee      93  66  90  64  82  53 /   0   0   0   0   0   0
Omak           95  60  93  59  86  51 /   0   0   0   0   0   0

&&

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

&&

$$


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