Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 110429
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
929 PM PDT Wed Aug 10 2022

.SYNOPSIS...
Thunderstorm chances are expected to increase across north-central
Washington overnight. Additional chances for showers and
thunderstorms are forecast for portions of the region for the
remainder of the week. Temperatures will remain very warm through
Friday with highs in the upper 80s and 90s. After a brief cool
down into the 80s this weekend, hot weather is forecast to return
next week.

&&

.DISCUSSION...

Tonight through Friday night: The Northwest is sandwiched between
a deep upper level low pressure system off of the northern
Oregon coast and strong high pressure ridging over the central
Rockies. Southerly flow will pump moisture northward across the
Inland Northwest resulting in a high unstable atmosphere. As such,
dew point temperatures currently stand in the mid to upper 50s
across the region, which is quit juicy for early to mid August.
Mesoscale analysis off of SPC`s page indicates surface based CAPE
values of over 500 J/kg region wide. Cumulus is beginning to
bubble up over portions of eastern Washington, but this is being
capped by roughly 40+ J/kg of CIN. There is also a lot of high
cirrus streaming across the central to northern portions of the
Idaho Panhandle that will make it difficult for surface based
convection to fire over this portion of the region. CIN is weaker
over the higher terrain of eastern Oregon and thunderstorms (some
turning severe) are expected to push up into extreme southeastern
Washington through the late afternoon and evening hours today.
Surface based instability over northeast Oregon is greater with
CAPE values approaching 2,000 J/kg. Storms will be moving into a
less favorable environment for developing convection as they push
into southeast Washington. With that said, there is a concern for
gusty outflow winds from storms and these outflows would be
capable of popping up storms further north across our area.

Another area to watch for surface based convection where the CIN
is a bit weaker and upper level dynamics a bit more favorable
will be over the north Cascades. So far the cumulus development
there is minimal, but that could change as we move into the early
evening hours. Then the focus will shift to elevated convection
along a mid level boundary that is expected to stretch across
central Washington. The latest runs of the NAM and RAP indicate
500-1000 J/kg of MUCAPEs developing from around Wenatchee to the
Methow Valley and Okanogan Valley/Highlands after midnight
tonight. There isn`t a lot of forcing to work with to get
convection going, but I believe there will be just enough for
thunderstorms to develop late tonight. This elevated convection
will occur over a relatively narrow strip with storms capable of
producing frequent cloud to ground lightning strikes and gusty
outflow winds. Lightning may result in new fire starts. We have
upgraded the Fire Weather Watch to Red Flag Warnings with this
threat continuing till about noon on Thursday.

The synoptic level pattern will change little Thursday into
Friday. The higher terrain Thursday afternoon will see the best
potential for isolated thunderstorms. Best instability at mid
levels shifts more into the Panhandle Thursday night into Friday
morning where an isolated threat of nocturnal thunderstorms is
possible. This isolated thunderstorm threat will continue over
mostly extreme eastern Washington and into the Idaho Panhandle
through Friday night. The main concern will continue to be for new
fire starts from lightning. Southerly winds will also become a
bit more breezy Thursday into Friday, but not strong enough to
meet criteria for critical fire weather conditions. /SVH

Saturday through Wednesday: Ensembles suggest Saturday`s upper
level flow remains southwest between a negatively tilted open
wave over the British Columbia Coast and a negatively tilted ridge
more or less generally oriented over Central Montana and up
across Alberta. This flow seems void of significant disturbances
so the forecast remains dry however surface winds appear to be a
bit robust from the southwest and somewhat gusty as if a dry cold
front of sorts may get dragged north/northeast in this flow. By
Sunday the earlier mentioned open wave is expected to have moved
northeast and away from the area which still allows for a slight
southwest flow and perhaps a subtle increase in 500mb heights
essentially allowing for similar conditions as Saturday. Monday
thru Wednesday ridge amplification is expected to take place and
is most apparent in the return of hot temperatures with dry
conditions. /Pelatti

&&

.AVIATION...
06Z TAFs: Moisture streaming up from the south will keep the
potential for not only clouds but some showers and thunderstorms
for the next 24+ hours. KLWS & KPUW will have the best chances at
seeing thunderstorms into the overnight hours. Gusty outflow
winds are possible from any storms that do form. /KD

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        63  91  63  96  61  87 /  10  10  20  10  10  10
Coeur d`Alene  61  91  61  96  59  87 /  10  10  20  20  10  10
Pullman        58  88  58  91  56  83 /  20  10  20   0  10  10
Lewiston       69  95  68  99  67  92 /  30  10  20  10  10  10
Colville       55  91  53  96  53  89 /  20  20  10  20  10  10
Sandpoint      60  91  58  93  57  86 /  20  10  20  20  20  10
Kellogg        66  89  67  93  63  84 /  10   0  20  10  30  10
Moses Lake     63  93  61  97  58  90 /  10   0   0   0  10  10
Wenatchee      68  94  66  96  63  88 /  20   0   0  10  10  10
Omak           64  93  63  98  61  93 /  20  40  10  10  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Red Flag Warning from 1 AM to noon PDT Thursday for Colville
     Reservation (Zone 702)-Foothills of Central Washington
     Cascades (Zone 705)-Methow Valley (Zone 704)-Okanogan
     Valley (Zone 703)-Waterville Plateau (Zone 706).

     Red Flag Warning until noon PDT Thursday for East Washington
     North Cascades (Zone 698).

&&

$$


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