Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 210928

Area Forecast Discussion
National Weather Service Spokane WA
228 AM PDT Wed Aug 21 2019

Today a cold front will produce gusty winds and a chance for
rain. Shower chances linger over Idaho Thursday, then limited
chances linger along the Canadian border Friday afternoon.
Temperatures cool after today, with highs in the upper 70s and 80s
through the middle of next week. Otherwise the weather looks
mostly dry.


Today through Thursday: A cold front moves across the region with
the threat of rain and increased winds. Winds will be most
notable this afternoon and evening as the leading gust front
crosses west to east. This morning the cold front was coming onto
the coast. It will push inland through the day and evening, before
moving to the Panhandle overnight. This morning the main rain
chances will be around the Cascades. This afternoon the risk
expands to the north-central WA through western Columbia Basin.
Then late this afternoon into evening the rain threat expands into
the eastern third of WA and the ID Panhandle. Overnight the
threat of precipitation backs against the Cascade crest and shifts
into the eastern third of WA and the ID Panhandle, with the
overall best risk over the ID Panhandle. The risk wanes elsewhere.
Some thunderstorms may be mixed in around the northern mountains
in the late afternoon and evening and then around the Panhandle
late in the evening and overnight, where some pockets of
instability lay.

Winds will be the second but the more noticeable and potentially
more impacting feature of the system. Speeds gradually increase
through the morning to midday, before a more notable gust front
starts to push east from the Cascades into the Columbia Basin
through the afternoon (1-4 pm). The gust front spreads into the
eastern third of WA and lower Idaho Panhandle in the late
afternoon and early evening (4-7 pm). This could bring a quick
1 or 2 hour period winds with speeds of 15-25 mph, with gusts of
30 to 45 mph. The more sheltered mountain valleys are expected to
see 8-15 mph winds with gusts to 20-30 mph. Possible impacts: (1)
This could lead to some pockets of blowing dust over the Columbia
Basin into the Palouse. (2) Area bodies of water could see some
chop and wind waves which may impact smaller vessels. (3) The
sudden burst of winds could lead to some minor tree damage,
especially for any weakened or dead trees and branches fallen on
power lines could yield a few power outages.

Thursday the front continues to shift east. The main threat of
precipitation in the developing northwest flow lingers around the
mountains of northeast WA and the ID Panhandle. Some shallow
instability over north Idaho will keep a threat of embedded
thunderstorms alive, but the risk is slight.

Temperatures will be remain warm today, but values are expected
to be cooler than yesterday. Thursday, however, temperatures will
be slightly cooler than normal on the backside of the cold front.

Thursday night through Sunday: Dry weather is expected Thursday
night as the upper trough exits the region. Nearly zonal flow
aloft will set up over the Pacific Northwest Friday and continue
through the weekend. Guided by a strong westerly jet stream over
the eastern Pacific, weak weather systems will likely pass through
this flow. A slight chance of showers is expected mainly over the
mountains along and north of the Canadian border. More notably,
these weather systems will bring the potential for breezy west to
southwest winds across east slopes of the Cascades, Waterville
Plateau, the Palouse, and into the Spokane area. Both Saturday and
Sunday could be breezy days. Temperatures through Sunday will be
within a few degrees of normal for this time of year.

Monday through Wednesday: High pressure will begin to amplify over
the eastern Pacific early next week, with northwesterly flow over
the Inland NW. Shortwave energy may clip far northern Idaho during
this time and bring a slight chance of showers. High pressure
will then likely build inland toward the middle of next week,
bringing a warming trend to the region. /Dang


06Z TAFs: Rich moisture streaming into the region ahead of
a Pacific cold front will result in broken to overcast mid
and high clouds at or above 10,000 feet AGL.  The cold front
will move into Central WA 19-21Z and slowly migrate east
into KGEG-KPUW-KLWS-KCOE 00-04z.  Bands of showers will
develop along the front and could result in brief rain at
area terminals.  We are looking for a weak marine push of
west to southwest winds 08-10z.  Pullman may gusts near 20 mph
briefly.  Of greater aviation concern will be strong gusts
developing ahead of the cold front.  While southwest winds will
increase in the morning and afternoon, it will be a sharp wind
shift to west/northwest and gusts 25-35 mph that is a concern
to aviation, especially general aircrafts.  This will also
bring a brief threat for haze from patchy blowing dust.  /sb


Spokane        87  55  79  53  80  55 /   0  40  10   0   0   0
Coeur d`Alene  88  57  77  52  79  53 /   0  50  20   0  10   0
Pullman        86  51  76  48  80  51 /   0  50  10   0   0   0
Lewiston       93  63  82  57  87  61 /   0  50  10   0   0   0
Colville       92  49  85  45  83  44 /  20  30  20   0  10  10
Sandpoint      86  55  75  50  77  50 /   0  50  40   0  10  10
Kellogg        86  58  72  54  75  56 /   0  70  40   0  10   0
Moses Lake     88  55  83  52  85  55 /  30  50   0   0   0   0
Wenatchee      82  59  81  59  83  60 /  40  40   0   0   0   0
Omak           85  56  83  57  82  55 /  40  40   0   0   0   0




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