Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 280939
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
239 AM PDT Sun May 28 2017

.SYNOPSIS...
High pressure continues building over the Inland Northwest early
this week. There is a small chance of thunderstorms in the higher
elevations between Sunday and Tuesday. Otherwise expect dry and
warm weather, with afternoon highs in the 80s. This mild weather
will contribute to rises on rivers in the Cascades to north Idaho.
A cold front pushes in Wednesday, with additional disturbances
behind it through the end of the week. This will bring more
seasonal temperatures, with the return of rain and thunderstorm
chances.


&&

.DISCUSSION...
Today through Monday: Mostly dry, warm conditions will dominate
the weather. A 500mb ridge will continue to build in over the next
day and a half. Its modest subsidence will dampen any "significant"
threat of precipitation and most clouds. However a few high
clouds may spill through from time to time. Also each afternoon
brings increased convective instability. Subtle impulses rounding
the top of the ridge and weak orographic lift will allow for some
cumulus development, particularly around the mountains. A few
showers or embedded thunderstorms will also be possible each
afternoon around the Cascade crest and northern mountains,
particularly northern ID. Winds will generally be light and
diurnally drive, though there may be some brief breezy drainage
winds early Monday near the Purcell Trench (KSZT to KCOE) and near
the higher Palouse. Temperatures will continue to trend warmer,
with highs in the 80s to low 90s today and few degrees milder
tomorrow. /J. Cote`

Tuesday and Tuesday night...One more day of relatively quiet and
warm conditions will grace the region on Tuesday with a slightly
increased chance of afternoon and evening thunderstorms on the
Cascades as an upstream trough approaches the area. High
temperatures will be about the same as Monday`s highs as the upper
ridge axis slides eastward and morning lows on Wednesday will be
mild as the surface thermal trough remains anchored over the
basin.

Wednesday and Wednesday evening...Models are coming into good
agreement that Wednesday will be the day the ridge breaks down. As
is usually the case after multiple days of warm
temperatures...this process will be accompanied by a heightened
risk of thunderstorms over the entire region...probably in the
west during the morning hours and spreading eastward across the
basin and into the Idaho Panhandle during the afternoon and
evening hours. Models clearly depict a strong short wave passage
dragging along a surface cold front which will assist dynamic
support for thunderstorm initiation and sustainment. This will
also create breezy conditions especially near the Cascades during
the afternoon and evening. It is too far out to get a good handle
on how strong any thunderstorms will be yet...but Wednesday
appears to present the best chance this week of an active regime
of organized convection over the region.

Thursday through Saturday...Model agreement deteriorates during
this return to a more progressive and seasonably cooler regime.
The ECMWF model is preferred owing to better run-to-run
consistency and depicts a series of weaker short wave disturbances
through the weekend. This augers for cooler and more seasonable
temperatures with a chance of showers and garden variety
thunderstorms each afternoon and evening...concentrated on the
mountains ringing the basin with persistent west/southwest winds
and occasionally breezy. /Fugazzi

&&

.AVIATION...
06Z TAFS: Some very thin cirrus streaming over the ridge.
Otherwise clear skies overnight and into Sunday morning. Flat cu
will develop again Sunday aft 19Z and dissipate aft 00Z. Winds
will remain light. Isolated showers and maybe a lightning strike
is possible in the afternoon across extreme NE WA and north ID. No
threat of any of this moving over TAF locations.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        83  57  86  59  87  59 /   0   0   0   0   0   0
Coeur d`Alene  82  54  85  56  86  55 /   0   0  10   0   0  10
Pullman        81  52  83  53  85  56 /   0   0   0   0   0   0
Lewiston       87  57  89  59  90  60 /   0   0   0   0   0  10
Colville       84  55  87  56  88  56 /   0   0  10  10   0   0
Sandpoint      80  51  81  52  82  53 /  10  10  10  10   0  10
Kellogg        82  50  82  54  84  54 /  10  10  10   0  10   0
Moses Lake     89  55  92  57  93  61 /   0   0   0   0   0  10
Wenatchee      87  60  89  62  90  63 /   0   0   0  10  10  30
Omak           87  56  88  58  89  58 /   0   0  10   0   0  20

&&

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

$$



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