Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 292358
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
458 PM PDT Fri Jul 29 2016

.SYNOPSIS...
Cascade gap winds will pick up this evening. A dry cold front
passes Saturday, creating breezy conditions and an increased risk
for spreading grass fires. Another breezy cold front will be
possible late Monday into early Tuesday. Temperatures will be
cooler Sunday into the first part of next week, with an
occasional threat for showers and thunderstorms in and around the
northern mountains Tuesday and Wednesday.

&&

.DISCUSSION...
Tonight through Sunday: Warm and breezy weather can be expected
for the weekend. Cumulus build ups over the mountains will linger
into the evening along with the small chance of a thunderstorm
near the Canadian border. The heat of this afternoon will
gradually moderate as the ridge of high pressure flattens. This
will begin this evening as a weak push takes place across the
Cascades and gap winds increase. There is not much of a marine
layer influence on the west side of the state. So when the surface
pressure gradients tighten this evening, little in the way of a
humidity relief will be experienced in the Cascade valleys.
Locally breezy winds will be found in the Kittitas and Wenatchee
valleys with gusts to 20 mph, which will raise concerns for the
land agencies but the conditions will be short lived. Expect mild
temperatures overnight into Saturday morning. By Saturday
afternoon, a cold front will swing in from the west by Saturday
afternoon and increase winds across from the Cascades and across
the Columbia Basin, for a larger area and for a longer duration.
West to southwest will increase to 15-20 mph with gusts to 25 mph.
This coupled with low humidities will raise fire weather concerns.
Will upgrade the fire weather watch to a red flag warning for
Saturday afternoon for much of the lowland areas. Meanwhile,
temperatures will cool by 5-8 degrees. There is a small chance of
convection in the northern mountains but should be confined to the
Canadian border. The winds will lose their gustiness late Saturday
night, but pressure gradients continue the potential for breezy
winds into Sunday morning especially for the Cascade valleys and
the western Columbia Basin, and then taper off by afternoon.
Temperatures will continue to cool by 6-10 degrees, falling below
seasonal normals again. There will be plenty of dry air aloft at
the low and mid levels that will limit in the way of clouds or
precipitation. /rfox.

Sunday Night and early Monday: The system that brought the winds
Saturday will be well off into northern Alberta, and the next low
pressure system to move through the Pac NW will be nearing the WA
coast. The forecast will remain dry and temperatures right around
average for this time of the year.

...GUSTY WINDS POSSIBLE LATE MONDAY NIGHT AND EARLY TUESDAY
MORNING FOR THE EAST SLOPES OF THE CASCADES AND INTO THE
WATERVILLE PLATEAU...

Monday Evening through Tuesday: The GFS and ECMWF have slowed
down the timing of the closed low to move into the region, which
makes sense given how strong this cold front will be. Winds will
increase starting Monday evening and will continue through the day
on Tuesday, with the strongest winds early Tuesday morning. A 90+
kt jet will move into the Cascades late Monday evening into
Tuesday morning. There is the potential for some stronger wind
gusts to mix across the mountains and higher plateaus...mainly
south of Lake Chelan eastward into portions of the Waterville
Plateau. Have increased the wind gust potential during the 06Z-12Z
Tuesday time frame. The front will move through during the
overnight and morning period. The best chance for showers and
thunderstorms with this front will be across the north, generally
north of Highway 2. Tuesday will be the coolest day of the week
with valley temperatures in the 70s to lower 80s.

Wednesday through Friday: The low keeps moving east as a
shortwave ridge builds along the west side of the state. There is
the potential for some additional showers and thunderstorms on
Wednesday along the canadian border in the afternoon. Otherwise we
dry out. The ridge shifts east over eastern WA and north ID
Thursday as the next closed low begins to move out of the Gulf of
Alaska and into northern British Columbia. Wednesday temperatures
will remain below average in the wake of the cold front. But by
Thursday and Friday we warm back up into the mid 80s to lower 90s.
/Nisbet

&&

.AVIATION...
00Z TAFS: VFR conditions expected at all TAF sites through
Saturday afternoon. Isolated thunderstorms expected over the
northern mtns near the Canadian border this evening and then
dissipating overnight. Skies will remain clear tonight into
Saturday. A dry and weak cold front passage will result in breezy
winds for Saturday. Expect sustained winds of 12-18 kts with
gusts up to 25 kts across the basin and into the more exposed
areas near Spokane on the Palouse. A tighter pressure gradient
across the Cascade Mtns will result in windier conditions at KEAT
Saturday afternoon with gusts to around 30 kts possible. /SVH

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        65  90  58  82  58  86 /   0   0   0   0   0   0
Coeur d`Alene  62  89  55  81  54  86 /   0   0   0   0   0   0
Pullman        56  88  49  81  50  87 /   0   0   0   0   0   0
Lewiston       67  97  60  90  60  95 /   0   0   0   0   0   0
Colville       57  91  54  84  51  88 /   0   0   0   0   0   0
Sandpoint      55  86  52  79  49  83 /   0   0   0   0   0   0
Kellogg        60  87  53  78  51  84 /   0   0   0   0   0   0
Moses Lake     62  95  58  88  57  90 /   0   0   0   0   0   0
Wenatchee      69  92  63  86  61  88 /   0   0   0   0   0   0
Omak           63  93  59  88  59  90 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Red Flag Warning from 1 PM to 9 PM PDT Saturday for East
     Washington Central Cascade Valleys (Zone 677)-East
     Washington Northern Columbia Basin (Zone 673)-East
     Washington Palouse and Spokane Area (Zone 674).

&&

$$


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