Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 291123
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
423 AM PDT Mon May 29 2017

.SYNOPSIS...
High pressure continues over the Inland Northwest through Tuesday
with unseasonably warm temperatures. There is a small chance of
thunderstorms in the higher elevations, otherwise expect dry
weather. This warm spell will contribute to rises on rivers from
the Cascades into north Idaho. A cold front arrives Tuesday night
with a better chance of showers and thunderstorms. This will be
followed by cooler and unsettled weather for Wednesday into the
rest of the week.


&&

.DISCUSSION...
Today through Tuesday: Warm weather continues, with limited shower
and thunderstorm chances. A ridge of high pressure centered over
the Inland NW this morning will start to edge east. Moisture
lingering around the north to eastern CWA and increasing toward
the Cascades with be accompanied by the reemergence of afternoon
instability. Subtle vorticity lobes in the westerly flow and
orographic ascent will lead to an increase in cumulus about the
mountain zones this afternoon. This will be accompanied by a
slight risk for showers and thunderstorms in the Cascades, the
northern WA and ID Panhandle mountains, as well as the Blues.
Tonight the risk will wane for most locations with the loss of
daytime heating, though some threat may linger near the Cascade
crest with the onshore flow. Tuesday the ridge axis shifts into
the northern Rockies and the southwest flow increases. Moisture
further deepens around the Cascades ahead of the approaching
system. A limited shower and thunderstorm threat will be found
near the Blues and far northeastern mountains with the afternoon
heating and instability. A better threat of showers and
thunderstorms will be developing within the Cascades, especially
late. Middle to high clouds will gradually increase from the west
elsewhere. Easterly winds will increase. Temperatures will remain
above normal by about 10-15 degrees, with afternoon highs in the
80s to lower 90s. Tuesday will be the warmest day for most spots.
The main exception will be toward the Cascades where the increased
onshore flow and increased cloud cover and shower chances may
hold temperatures down compared to today. /J. Cote`

Tuesday night and Wednesday: Models are in good agreement in
breaking down the warm upper ridge with an initial short wave
passage and surface cold front Tuesday night and into Wednesday
morning. The main frontal transit will occur overnight Tuesday and
into Wednesday morning...not the most favorable time for serious
thunderstorm activity...however enough mid level instability and
plenty of moisture will be able to be exploited by the short wave
dynamics to produce a few thunderstorms moving off the Cascades in
the evening and nocturnally transiting the basin and northern
mountains overnight...and redeveloping with a surface based
instability component during the day Wednesday concentrated over
the Idaho Panhandle. Otherwise...breezy conditions will develop
over the basin as cooler air behind the front invades through the
Cascade gaps. A general threat of showers with a few thunderstorms
looks plausible during this evolution.

Wednesday night through Sunday: Although timing differences
develop between models through this period...all of them depict a
series of short wave disturbances transiting the forecast area in
a more progressive pattern for the remainder of the week and into
next weekend. None of these waves look particularly strong...but
each will be capable of triggering some showers or a few
thunderstorms mainly over the mountains north and east of the
basin...with occasionally breezy conditions in the basin itself.
Temperatures will cool back into the normal range during this
pattern...with mainly 70s readings in the populated areas during
the day and 40s to lower 50s at night. /Fugazzi

&&

.AVIATION...
12Z TAFS: Dominating ridge will lead to VFR conditions at all TAF
sites. Isolated thunderstorms possible near the Cascade crest and
over the higher terrain of northeast WA and the northern ID
Panhandle this afternoon, away from the TAFs. /J. Cote`


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        86  60  87  58  75  53 /  10   0   0  40  20  10
Coeur d`Alene  84  56  86  55  74  51 /  10   0   0  30  20  20
Pullman        83  55  85  55  73  52 /  10   0   0  20  20  30
Lewiston       90  59  91  61  80  56 /  10   0   0  20  20  30
Colville       87  56  87  58  76  52 /  10   0   0  40  40  20
Sandpoint      83  53  84  54  75  49 /  10  10  10  10  40  40
Kellogg        84  53  84  53  76  47 /  10  10   0  10  30  50
Moses Lake     92  58  94  60  83  55 /  10   0   0  40  10  10
Wenatchee      90  64  89  58  80  58 /  10  10  10  30  10  10
Omak           89  58  90  60  81  53 /  10  10  10  50  40  10

&&

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

$$


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