Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 192128

Area Forecast Discussion
National Weather Service Spokane WA
228 PM PDT Sat Aug 19 2017

Our weather for rest of the weekend will feature dry weather and
seasonably warm temperatures. Skies are expected to be mostly
clear on Monday for the eclipse however there may be some smoke in
the northern valleys. Tuesday and Wednesday will be quite warm
with afternoon temperatures in the 90s. A vigorous cold front on
Wednesday night will have the potential to produce thunderstorms,
with strong winds expected on Thursday.


Tonight through Monday...
Predominately northwest flow across the region has brought smoke
back into the northern parts of Washington and Idaho. The smoke
sources appear to be from B.C. Canada and the active Diamond Creek
and Bridge Creek fires. Some air sensors are beginning to show
surface based impacts Laurie, Colville southward with readings as
`Unhealthy for Sensitive groups`. Smoke is likely to persist
through Sunday with varying intensity. Further downstream into the
Idaho Panhandle smoke will thin out to what looks like a hazy sky
so the forecasts will reflect these conditions through the rest
of the weekend.

Expect another round of breezes tonight coming off the Cascade
east slopes gusting to 20 mph. Elsewhere winds will be 10 mph or
less overall.

Sunday cloud cover will increase as a weather disturbance again
clips through BC into Montana. There will be no precipitation and
it is hard to say how much clearing of smoke there will be Sunday
afternoon and evening. At this time it looks as if smoke will
likely hang in northeast WA and the ID Panhandle potentially into
Monday. High temperatures on Sunday will still hover around 80
degrees which is normal for this time of year and winds will be

High pressure begins to build into the region Monday with little
cloud cover expected for the eclipse period. However with a
northerly surface wind tendency the northern valleys could still
be susceptible to some smoke Monday morning. Afternoon high
temperatures will be warming well into the 80s on Monday. TC

Monday night through Saturday: The ridge of high pressure will be
over the Northwest on Tuesday bringing us the hottest day of the
week. On Wednesday, the ridge has shifted well east of our area,
allowing temperatures aloft to cool a bit. Additionally,
thunderstorms will develop over eastern Oregon in the afternoon.
High clouds from these storms could also provide a tad bit of
cooling for us. It probably won`t be noticeable, but Wednesday
should be a degree or 2 cooler than Tuesday.

Then the more interesting weather arrives. With the eastward shift
of the ridge, a deep trough approaches from the west.
Thunderstorms may fire over the southeast WA mountains during the
afternoon, but it appears that the main activity will wait until
the evening hours on Wednesday. The best chance of
showers/thunderstorms will be east of a line from Walla Walla to
Bonners Ferry, but there`s an outside chance of some precipitation
for Spokane and Colville. At this point, I`m not overly excited
about the chances for any one to see rain. The convection will be
elevated with a significant dry layer near the surface to
evaporate some of the rain that is generated. And there`s no
synoptic lift mechanism to support the convection. We`ll see if
there are any changes with future model runs.

On Thursday, the cold front will have swept through the area and
be well east of us. The post-frontal environment should be windy
in most locations. The timing of the front isn`t perfect for a
strong wind event, but that could change as we get closer to the
event. Blowing dust could certainly be an issue in the Basin,
Palouse, and into the Panhandle. Fire weather concerns will be the
greatest (see below for more). With the deep trough passing by to
our north over BC, there`s an outside chance of a thunderstorm
near the Canadian border.

Temperatures on Thursday will be considerably cooler, and even a
few degrees cooler still on Friday, before a warming trend begins.
Long range models agree on hot weather returning, so it doesn`t
look like summer is over just yet.  RJ


12Z TAFS: Expect VFR conditions after a recent cold front passage
with dry northwest flow. Some locally breezy conditions gusting
15-20 mph will persist into the afternoon. KEAT will have
increasing wind as well as surrounding areas after 01z until 14Z
Sunday. With limited moisture expect some cumulus cloud
development over the mountains. Smoke will increase near the
Canadian border and move south but is not expected to restrict
visibility to MVFR conditions at this time. /TC


A strong cold front will move through the region Wednesday night.
Ahead of the front, thunderstorms will affect the Panhandle and
extreme eastern WA Wednesday night. Confidence isn`t high of any
wetting rains from these storms, and the shower activity will
probably not be widespread.

Thursday will be a windy day. Wind gusts to 30 mph are possible
across the Basin. Despite the 10 degrees of cooling, relative
humidities will remain very low for continued fire danger.  RJ


Spokane        55  81  57  86  60  91 /   0   0   0   0   0   0
Coeur d`Alene  52  80  53  86  55  91 /   0   0   0   0   0   0
Pullman        51  79  52  86  54  91 /   0   0   0   0   0   0
Lewiston       58  87  60  92  62  97 /   0   0   0   0   0   0
Colville       50  84  51  88  52  92 /   0   0   0   0   0   0
Sandpoint      45  78  46  86  48  90 /   0   0   0   0   0   0
Kellogg        49  77  50  84  53  90 /   0   0   0   0   0   0
Moses Lake     53  86  55  90  57  95 /   0   0   0   0   0   0
Wenatchee      60  86  62  90  64  94 /   0   0   0   0   0   0
Omak           57  88  59  92  60  95 /   0   0   0   0   0   0



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