Flash Flood Warning 29, NWS Spokane, WA

287 
WGUS76 KOTX 140236
FFSOTX

Flash Flood Statement
National Weather Service Spokane WA
736 PM PDT Tue Sep 13 2022

WAC019-140246-
/O.EXP.KOTX.FF.W.0029.000000T0000Z-220914T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Ferry WA-
736 PM PDT Tue Sep 13 2022

...FLASH FLOOD WARNING FOR THE SUMMIT TRAIL BURN SCAR WILL EXPIRE AT 
745 PM PDT THIS EVENING FOR CENTRAL FERRY COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed any remaining road closures.

A Flood Watch remains in effect until 800 PM PDT Wednesday for a 
portion of Northeast Washington.

LAT...LON 4846 11842 4847 11843 4843 11828 4842 11827
      4838 11844 4838 11842 4836 11841 4835 11845
      4831 11843 4828 11855 4836 11853 4839 11859
      4845 11854 4846 11850 4843 11855

$$

Butler

Area Forecast Discussion
National Weather Service Spokane WA
439 PM PDT Tue Sep 13 2022

.SYNOPSIS...

Clusters of slow moving thunderstorms will develop over north
central Washington this afternoon and spread into eastern
Washington and north Idaho overnight. Locally heavy rain will be
possible over the steep terrain of the north Cascades and Okanogan
Highlands. Redevelopment of showers and thunderstorms is likely
Wednesday along the Canadian border. The combination of rain, cool
temperatures, and a subtle increase in west winds should bring
gradual improvements to our air quality Wednesday into Thursday.
The weekend will be cooler with daytime temperatures in the 60s
and morning lows in the 40s and a few 30s.

&&

.DISCUSSION...

This evening and through the night: Showers and thunderstorms over
north central Washington will increase late in the afternoon into
the evening as an upper low over the Olympic Peninsula (as of 2
PM) slowly migrates east through the night. Through the night,
look for scattered showers and thunderstorms to spread into
eastern Washington and north Idaho. While our precipitable water
values and surface dewpoints aren't particularly high, the
combination of upper level difluence and weak mid-level flow will
contribute to an environment conducive for slow moving showers and
thunderstorms, mainly in north central Washington. A Flash Flood
Watch is in place for Chelan, Okanogan, Ferry, and Stevens
counties this afternoon into Wednesday. Widespread flooding is not
anticipated, but slow moving cells that develop over flood prone
areas may cause problems with rock/mud slides and rapid rises on
creeks and streams. Steep terrain, urban areas, and burn scars are
a particular concern. While the rain may cause some localized
problems, precipitation will benefit our region which has been
very dry since mid July.

Wednesday: During the day Wednesday, our slow moving upper low
will pivot across northeast Washington into southern British
Columbia. High resolution models predict a lull in shower activity
in the morning with a redevelopment for our counties along the
Canadian border during the afternoon. Similar to today,
atmospheric moisture and instability will be sufficient for
thunderstorms development. Once again, slow moving cells capable
of locally heavy rain will be monitored closely in Okanogan,
Ferry, and Stevens counties.

Thursday and Friday: A weak upper level trough will persist over
the Pacific Northwest Thursday and Friday. With the departure of
our upper low Wednesday night, precipitation chances will be very
low on Thursday with a slight increase up to 20 percent along the
Canadian border on Friday afternoon. Seasonal temperatures will be
on tap with highs in the 70s and lows in the 40s and 50s.

Saturday through Wednesday: The upper level weather pattern
begins to take on a more Fall-like pattern as we head into the
weekend. The trajectory of where this upper level trough is
originating in the Gulf of Alaska will bring southward much cooler
air. The weather system has little signature of moisture with the
percentile of precipitable water showing about normal for this
time of year.

The cluster analysis of ensemble members by Sunday is a three-way
tie between deepening the Low off shore, a weaker longwave trough
down the West Coast, or a digging trough into Oregon. The EC
ensemble favors more of the longwave trough extending southward
and swinging through the Great Basin over the weekend; a more
progressive solution. The GFS and Canadian ensembles would be more
in favor of a deeper, cut-off Low off the California coast. What
would this mean for our sensible weather in the Inland Northwest?
This could lead to cooler, more unstable weather over the weekend
with a dry boundary layer and high level moisture (partly cloudy
skies).

While uncertainty is quite large for exactly which model solution
to lean harder on, the overall agreement to a more troughy and
cooler pattern seems probable. CPC has introduced a slight chance
for below normal temperatures as we head out into the far extended
(next week). This time of year, mid September, brings normal
daytime high temperatures in the low 70s and right now the
forecast is showing upper 60s. /Dewey

&&

.AIR QUALITY AND SMOKE...
The combination of precipitation, higher humidity, and
temperatures trending cooler than they were the last few weeks
should bring gradual improvements to air quality for much of the
Inland Northwest. Over the next 24 to 36 hours, parts of Idaho,
southern British Columbia, northern Washington, and northeast
Oregon should experience enough shower activity to wet a
significant number of our active fires. And a persistent upper
level trough should lead to several days of a prevailing west or
southwest flow. While late summer morning inversions will be slow
to break leading to thick smoke near fires, in general the
combination of wetter and cooler conditions and a cleaner west
flow should lead to gradual improvements in our smoky skies this
week into the weekend. /GKoch

&&

.AVIATION...
00Z TAFs: Scattered showers and thunderstorms will accompany the
passage of a slow moving upper low this evening through the
overnight. VCSH have been included at most TAF sites this evening.
High resolution models predict the development of a band along the
WA/ID border between 10-15z which is enough to include prevailing
showers at Pullman and Coeur d'Alene. A gradual improvement in the
visibility is predicted through the night as the upper low crosses
the Cascades leading to a cleaner west wind through the night and
into the day Wednesday. Visibility forecasting with smoke is a
low confidence endeavor. The HRRR smoke model is frequently better
at forecasting the arrival of smoke than the departure of it.
/GKoch

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        53  74  50  77  50  74 /  40  20   0   0   0   0
Coeur d'Alene  52  74  50  77  48  73 /  40  40   0   0   0   0
Pullman        47  73  45  73  43  71 /  40  40   0   0   0  10
Lewiston       59  80  56  80  54  78 /  30  30   0  10   0  10
Colville       43  73  41  78  41  75 /  50  60  10   0  10  10
Sandpoint      48  71  45  74  45  71 /  30  50  10   0  10  10
Kellogg        55  71  53  73  52  71 /  20  50  10   0  10  10
Moses Lake     50  78  49  80  48  76 /  40  10   0   0   0   0
Wenatchee      56  76  57  78  54  74 /  40  10   0   0   0   0
Omak           54  78  53  80  52  78 /  70  40  10  10   0  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flood Watch through Wednesday evening for Central Chelan County-
     Okanogan Highlands-Okanogan Valley-Upper Columbia Basin-
     Wenatchee Area-Western Chelan County-Western Okanogan
     County.

     Flood Watch through Wednesday evening for Northeast Mountains.

&&

Special Weather Statement
National Weather Service Spokane WA
327 PM PDT Tue Sep 13 2022

WAZ038-132300-
Okanogan Highlands WA-
327 PM PDT Tue Sep 13 2022

...A strong thunderstorm will impact portions of central Ferry County
through 400 PM PDT...

At 326 PM PDT, Doppler radar was tracking a strong thunderstorm near
Sherman Pass, or 44 miles east of Omak, moving northeast at 15 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Sherman Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4850 11857 4854 11865 4873 11854 4864 11834
TIME...MOT...LOC 2226Z 213DEG 12KT 4857 11857

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

JCLEV

Special Weather Statement
National Weather Service Spokane WA
407 PM PDT Tue Sep 13 2022

WAZ038-132330-
Okanogan Highlands WA-
407 PM PDT Tue Sep 13 2022

...A strong thunderstorm will impact portions of central Ferry County
through 430 PM PDT...

At 407 PM PDT, Doppler radar was tracking a strong thunderstorm near
Sherman Pass, or 47 miles east of Omak, moving north at 20 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Sherman Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4841 11851 4846 11866 4871 11857 4867 11825
TIME...MOT...LOC 2307Z 201DEG 19KT 4855 11850

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

Butler