Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 260919
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
219 AM PDT Fri May 26 2017

.SYNOPSIS...
High pressure builds in this weekend. A few showers and isolated
thunderstorms are possible around the Idaho Panhandle this
afternoon. Limited thunderstorm chances develop around the
Cascades, and perhaps the Canadian border, each afternoon between
Sunday and Tuesday. Otherwise expect dry, warm weather into early
next week, with afternoon highs in the 80s. This mild weather
will contribute to rises on rivers in central and north central
Washington. A threat of unsettled weather returns for middle to
late next week, with slightly cooler temperatures.


&&

.DISCUSSION...
Today through Saturday: A limited shower threat dissipates as
high pressure builds in with fairer, warmer weather. This morning
WV satellite imagery shows the Inland NW in a northerly flow with
the long-wave trough axis southeast of the area, while a ridge of
high pressure is starting to build in from the west. A weak
impulse drops across the eastern CWA this morning and afternoon.
This and some upslope flow will work with some afternoon
instability to keep a slight threat of showers in the forecast
around the Idaho Panhandle mountains, Blues and Camas Prairie.
Some embedded thunderstorms may also be found the central
Panhandle, Blues and Camas Prairie. The risk will wane with
sunset. A few models hint at potential mountain showers near the
Cascade crest this afternoon, but the overall risk is slim. By
Saturday afternoon models again hint at some risk for showers
around the mountains, Yet again the risk is too slim to include a
substantial mention in the forecast. If there are any, the better
risk will be toward the Canadian and Montana borders. As for the
remainder of the area, conditions today and Saturday are expected
to remain dry. The heating of the day and steepening lapse rates
will bring a few cumulus build ups around the mountains and
northeastern rim of the Columbia Basin in the afternoon hours,
more so today than Saturday. Otherwise a few higher clouds will
spill over the building ridge. Temperatures are expected to warm
above normal this afternoon and even further above normal
Saturday, with many areas seeing highs in the mid to upper 70s and
80s. /J. Cote`

Saturday night through Tuesday...Models are in good agreement and
very consistent over previous runs for this period. A strong upper
level ridge will dominate the region for a period of mainly
dry..clear and warm early summer-like conditions with light
terrain driven winds. Temperatures will increase every day through
Monday and stabilize by Tuesday as the upper ridge axis
approaches and migrates through the region. High and low
temperatures of 10 to 15 degrees above normal are expected over
all areas by Monday and Tuesday...with highs in the mid 80s common
with some 90+ readings in the lower valleys and deep basin.

There will be a small chance of weak but potentially moderate rain
producing thunderstorms mainly over the Cascades each afternoon
and early evening with a relatively moist mid level layer
providing some fuel...warm temperatures and steepening lapse
rates bringing some instability and mountains providing weak and
locally focused lift. Any showers and storms will be spotty and
will probably not move off of the high terrain...if they occur at
all.

Tuesday night through Thursday...Model agreement begins to
deteriorate for this period...however they are coming into closer
agreement regarding a break down of the ridge and the approach of
a potentially negatively tilted trough on or about Wednesday. The
GFS is the most aggressive...but has been delaying or waffling
with the timing over the last few runs. The EC model has been the
most consistent over the last few days in delaying a noticeable
change until later in the period. All models are beginning to
converge now...but details are still a bit nebulous. The best bet
is for an increasing chance of more general showers and
thunderstorms and a noticeable cool down over the western zones
on Wednesday and a general cooling trend and increasing risk of
showers and thunderstorms Wednesday night and
Thursday...especially Thursday when thunderstorms could be quite
beefy as the trough pushes through with a potentially strong cold
front at the surface. /Fugazzi


&&

.AVIATION...
06Z TAFS: Some mid to high level clouds will linger over the
region through tonight, especially over the Idaho Panhandle. High
pressure will begin to build on Friday. This will restrict shower
chances to over the Northeast Blue Mtns and the higher terrain of
the southern to central Idaho Panhandle. Isolated thunderstorms
with this convection Friday afternoon will be possible as well,
but is not expected to impact the TAF sites. /SVH



&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        73  51  78  55  82  57 /  10   0   0   0   0   0
Coeur d`Alene  72  47  78  49  81  51 /  10   0   0   0   0   0
Pullman        69  46  76  47  80  49 /  10   0   0   0   0   0
Lewiston       76  50  82  53  87  57 /  10   0   0   0   0   0
Colville       76  48  81  52  82  52 /  10   0   0   0   0   0
Sandpoint      71  43  76  46  78  47 /  10   0  10   0  10  10
Kellogg        71  43  77  46  79  47 /  20  10  10  10  10  10
Moses Lake     81  50  85  52  89  55 /   0   0   0   0   0   0
Wenatchee      80  55  85  57  88  59 /   0   0   0   0   0   0
Omak           80  51  85  52  87  53 /   0   0   0   0   0   0

&&

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

$$


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