River Flood Warning 77, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
936 PM PST Mon Nov 26 2018

.UPDATE...
The forecast has been largely on track so far this
evening. Minor tweaks have been made to the POPs and QPF based on
latest trends. Evidence of a fairly expansive rain shadow can be
seen in MRMS radar imagery to the northeast of the Olympics. This
will continue to limit QPF to some extent. Do expect precip to
continue to be widespread overall thru the overnight hours as a
sfc frontal system pushes inland. Weather conditions should ease
up thru the day Tuesday in the wake of this storm system...tho
showers will continue to be possible.

Current river flood warnings for the Skokomish and South Fork
Nooksack rivers will continue...see FLSSEW for further details.
River flooding will continue to be monitored across Whatcom,
Skagit, and Snohomish counties as well across the majority of the
Olympics. In addition...winds will continue to remain elevated
across the coast and north interior. Recent obs have not been
overly impressive...with a few gusts above 40 mph noted but not
very widespread. As the front approaches the coast in the next
few hours do think there is potential for strong wind to pick back
up...tho if it is highly absent will consider cancelling the
warning early. If winds do pick up...will let the High Wind
Warning continue as planned.

Please see the previous discussion below for further details.

Kovacik

&&

.PREV DISCUSSION... /issued 420 PM PST Mon Nov 26 2018...corrected hydrology/

SYNOPSIS...A strong Pacific storm will bring locally heavy rain
and high winds to portions of Western Washington through tonight.
Rain and wind will ease Tuesday behind a cold front. Cool and
somewhat unsettled weather will prevail the rest of this week.

&&

.SHORT TERM...The UW Sandpoint profiler indicates strong
southwest flow, with winds close to 50 knots at 2k ft. An
atmospheric river of warmer moist air is being entrained into
Western Washington. Temperatures jumped a few degrees earlier as
this milder air has reached the interior, including Cascades. Any
freezing rain in the passes ended earlier as temperatures managed
to rise just above freezing. The winter weather advisory was
allowed to expire at noon. Snow levels will be high through
tonight, around 8k ft. The milder air and strong low level flow
should produce excellent orographic forcing. Storm total rain
amounts along favored slopes of the Olympics could approach 8
inches with up to 6 inches in the north Cascades. Several rivers
are forecast to flood given the additional heavy rain tonight. See
the latest hydrology section below and refer to the current river
statement for updated information.

Southeast winds have gusted to around 60 mph in a few spots this
afternoon. Strongest winds have been spotty but another bout of
gusty winds are expected along the front later tonight. The high
wind warning remains in effect for areas north of Puget Sound
through late tonight. Winds will ease Tuesday, except remain
breezy around Puget Sound with showers into Wednesday.

High tides Tuesday morning combined with low atmospheric pressure
will result in minor tidal overflow along coastlines north of
Puget Sound. Minor flooding is possible for a few hours around the
time of high tide roughly 8-9 AM PST Tuesday morning. See the
marine section below for details.

.LONG TERM...Models continue to struggle with the large scale
pattern Thursday through next weekend. Most global models show the
split flow pattern persisting through at least Friday. Systems
will pass mainly to our south with light rain brushing the area at
times. kept low chance pops in most periods of the extended given
the unstable model solutions.

Colder air could arrive next weekend if the ridge offshore
amplifies in the correct position near 140W. Most model runs do
not show much cold air making over the mountains, or even much
outflow. But models have not settled on details, but showers and
cooler temperatures are most. Mercer

&&

.AVIATION...A rather strong storm system will continue to impact
the area thru early Tuesday Strong southwesterly flow aloft will
continue with strong southerly winds continuing near the surface.
A surface front will approach the area this evening and push thru
the area thru the first half of the day Tuesday. This will keep
winds elevated during this time period with LLWS shear a concern
for the majority of tonight. Cigs are being a bit tricky this
evening as many sites are showing obs trending to BKN IFR.
Thinking many sites will be flirting between IFR and MVFR thru the
night before trying to recover thru the day Tuesday.

KSEA...Discussion above applies. Southeast wind 10-15 kt tonight
will become southerly 15g25 kt on Tuesday. LLWS will continue
tonight, but the winds aloft will decrease and the surface winds
will increase on Tuesday. Cigs down to IFR is possible.
CHB/Kovacik

&&

.MARINE...A strong frontal system will move through the inland
waters tonight. This front is expected to keep winds fairly strong
across the coast and inland waters...so gale warning will remain
in effect. Small craft for Puget Sound looks good with this update
as southerly winds and fairly strong gradients area look likely
all the way into Wednesday. Winds look to remain fairly light
across all waters thereafter. The next storm system could impact
the area towards the end of the week.

Kovacik

&&

.HYDROLOGY...Latest QPF has an additional 3 to 4 inches with
locally 5+ inches of rain over the Olympics and north Cascades. Snow
levels are very high at around 9000 feet. Rivers in both areas
are rising sharply and several heading above flood stage this
evening. Flood warnings continue for the Skokomish River and the
South Fork Nooksack River. Other points downstream on the Nooksack
are still forecast above flood. The Bogachiel and Skagit Rivers
are forecast to rise significantly and come close to flood stage.
Rivers in Jefferson County, including the Duckabush and
Dosewallips may also flood but there are few gages and no river
forecasts in those areas.

Models have shown good run-to-run consistency with heavy rain over
those two areas, but much less rain over the central and south
Cascades. Other rivers will also rise, but are forecast to not get
close to flood stage.
 jbb

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch through Tuesday evening for Admiralty Inlet Area-
     Bellevue and Vicinity-Cascades of Snohomish and King
     Counties-Cascades of Whatcom and Skagit Counties-Central
     Coast-East Puget Sound Lowlands-Eastern Strait of Juan de
     Fuca-Everett and Vicinity-Hood Canal Area-Lower Chehalis
     Valley Area-North Coast-Olympics-Western Skagit County-
     Western Strait of Juan De Fuca-Western Whatcom County.

     High Wind Warning until 4 AM PST Tuesday for Admiralty Inlet
     Area-Central Coast-North Coast-San Juan County-Western
     Skagit County-Western Whatcom County.

     Coastal Flood Advisory from 7 AM to 10 AM PST Tuesday for
     Admiralty Inlet Area-San Juan County-Western Skagit County-
     Western Whatcom County.

PZ...Small Craft Advisory for rough bar until 4 PM PST Tuesday for
     Grays Harbor Bar.

     Gale Warning until 4 AM PST Tuesday for Admiralty Inlet-Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From Cape Flattery To James Island Out 10 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From James Island To Point Grenville
     Out 10 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville
     To Cape Shoalwater Out 10 Nm-East Entrance U.S. Waters
     Strait Of Juan De Fuca-Northern Inland Waters Including The
     San Juan Islands.

     Small Craft Advisory until 4 AM PST Tuesday for Central U.S.
     Waters Strait Of Juan De Fuca-West Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Small Craft Advisory until 7 AM PST Wednesday for Puget Sound
     and Hood Canal.

&&

www.weather.gov/seattle

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
428 PM PST MON NOV 26 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0427 PM     HEAVY RAIN       2 NNW KINGSTON          47.83N 122.51W
11/26/2018  M2.00 INCH       KITSAP             WA   TRAINED SPOTTER

            RAIN BEGAN AT 3 AM AND REACHED 2 INCHES AT
            415 PM.

&&

GRUB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
633 PM PST MON NOV 26 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0633 PM     HEAVY RAIN       3 WNW SEKIU             48.28N 124.37W
11/26/2018  M4.48 INCH       CLALLAM            WA   TRAINED SPOTTER

            RAINFALL AMOUNT IS 24 HOUR AMOUNT AS OF 5
            PM.

&&

GRUB