High Wind in Washington, January 6, 2019

Area Forecast Discussion
National Weather Service Seattle WA
756 PM PST Sat Jan 5 2019

.UPDATE...Quick-hitting wind storm is still on track to impact
western Washington overnight. Analyzing the latest guidance has
increased concerns for a few area and some forecast adjustments
have been made this evening. The three hot spots of concern are:

* The Washington Coast from Neah Bay to the Oregon border between
  roughly midnight through 4 AM.
* The Seattle-Tacoma-Bremerton metro area between 1 AM and 5 AM
* The San Juan Islands between 3 AM and 6 AM.

In general winds gusts are expected to top out between 45 and 55
MPH, but a 2-3 hour period of gusts to around 60 MPH cannot be
ruled out. As a result, all of those areas have been upgraded to
a High Wind Warning. The Wind Advisory for the rest of the area
has also been expanded to include the Cascade foothills and
western Strait of Juan De Fuca. We will continue to monitor this
incoming storm system and update as needed.
-Wolcott-

&&

.SYNOPSIS...A frontal system will bring wind and rain tonight
with showers behind the system into Sunday. High pressure will
briefly dry things out on Monday. Wind and rain will return
Tuesday and Wednesday as a another frontal system moves through.
Unsettled weather will continue Thursday with some drying possible
by Friday.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Conditions remaining pretty
quiet and dry for much of the area this afternoon although
current radar already shows precip along the coast. Storm motion
remains from the south...so eastward progress will be driven more
by the approach of the actual trough itself. This is still
expected to occur gradually with precip finally getting into the
eastern portions of the CWA this evening. Guidance remains
consistent with precip amounts...including the snow amounts
progged for the Cascades...so the headlines covering the northern
and southern portions will not need to be extended into the
central...given that accumulations there will remain below
criteria and only 2-4 inches are expected in the passes. The main
expected impact from this system continues to be the sudden
increase in wind speeds overnight. Models remain consistent
showing speeds that meet Wind Advisory thresholds during the
overnight hours tonight and into Sunday morning with...as is
present in the morning update...the area of concern expanding into
two more zones...the southwest interior and the eastern strait.

The trough will traverse the area Sunday keeping precip in the
forecast exiting the area by early Monday morning. Although some
shortwaves may allow for lingering precip into Monday morning...this
appears to be relegated mostly to the Cascades. And while snow
levels in the wake of the exiting trough will drop down to around
1000 ft...the fact that the main threat of precip will have already
moved on makes any thoughts of lowland snow extremely unlikely. To
further cement that...an upper level ridge will build over the area
through the day Monday...making for generally dry conditions and
allowing snow levels to start to rebound. The next system to impact
the area will start to make its presence known early Tuesday morning
as a front associated with an upper level low out over the Pacific
will enter the CWA bringing a return to wet and windy
conditions...although models have backed off somewhat on initial
precip amounts with this system.  SMR

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...The upper low takes its
time approaching WA...allowing rains to continue into Wednesday.
As the system travels eastward...with will lose a bit of strength
and open up into a trough. Both ECMWF and GFS show this feature
pushing through the area by Wed night only to be followed by a
secondary trough during the overnight hours and into Thursday.
Rain does not look to start tapering off until Thursday night with
some attempt at an upper level ridge to build into the area...but
both models start this feature off as pretty dirty with
sufficient moisture remaining over the area to keep POPs into
early Friday morning. Currently...and surprisingly...both models
remain in agreement that this ridge looks to hold its ground
through the day Friday and into Saturday...allowing for a dry
first half of next weekend. SMR

&&

.AVIATION...Clouds and rain continue to increase out ahead
of the next Pacific frontal system. This will continue to be the
trend into the overnight hours. Generally all sites are VFR this
evening but as bulk of the heavier rain along the front moves in
overnight, should see ceilings drop to MVFR. In addition,
overnight the winds will rapidly pick up across the coast and
Puget Sound vicinity. Wind gusts to near 40-50kts will be
possible, the timeframe generally midnight to 4am along the coast
and 4am to 7am across Puget Sound. Winds will drop off rather
quickly into Sunday morning as the front clears the area. A trough
will linger across the area, allowing for scattered showers but
should see ceilings try to rebound back to VFR during the
afternoon.

KSEA...Rain will increase in coverage overnight tonight with VFR
ceilings expected to drop to MVFR overnight. Strong winds will quickly
develop tonight in the 09z-12z timeframe where winds could gust
to 40-50kt. Winds are expected to drop off rapidly after 12z with
ceilings trying to recover back to VFR in the afternoon.

Kovacik

&&

.MARINE...A strong Pacific frontal system is expected to move
across the area overnight tonight, bringing with it some strong
winds. Current gale headlines for the overnight hours look good,
but will be watching for the potential for storm force winds-
particularly across the central and eastern Strait where hi-res
guidance places 40-45kt sustained winds in around 09z or so. This
very strong push thru the Strait would be very short lived. After
the quick push of wind across the waters tonight, winds will
rapidly decrease from southwest to northeast as the main system
pulls away from the area, though will likely still see small
craft. The next system still looks to affect the area the first
half of next week.

Kovacik

&&

.HYDROLOGY...The Skokomish River remains above flood stage and
will continue to recede today. Light precipitation this afternoon
into Sunday may cause an additional small rise through Sunday.
Then the river will recede again and should fall below flood stage
early next week. Elsewhere, river flooding is not expected
through Monday. A wet system on Tuesday into Wednesday could cause
another round of minor flooding for rivers flowing off the
Olympics but precipitation amounts remain uncertain at this time.
CEO

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...High Wind Warning until 10 AM PST Sunday for Bremerton and
     Vicinity-Central Coast-North Coast-San Juan County-Seattle
     and Vicinity-Tacoma Area.

     Winter Weather Advisory until 10 AM PST Sunday for Cascades of
     Pierce and Lewis Counties-Cascades of Whatcom and Skagit
     Counties.

     Wind Advisory until 10 AM PST Sunday for Admiralty Inlet Area-
     Bellevue and Vicinity-East Puget Sound Lowlands-Eastern
     Strait of Juan de Fuca-Everett and Vicinity-Hood Canal Area-
     Lower Chehalis Valley Area-Southwest Interior-Western
     Skagit County-Western Strait of Juan De Fuca-Western
     Whatcom County.

PZ...Small Craft Advisory for rough bar until 1 PM PST Sunday for
     Grays Harbor Bar.

     Small Craft Advisory from 7 AM to 10 PM PST Sunday for 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.

     Gale Warning until 7 AM PST Sunday for Central U.S. Waters
     Strait Of Juan De Fuca-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-West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 7 AM to 4 PM PST Sunday for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca-Northern Inland Waters
     Including The San Juan Islands-West Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Small Craft Advisory from 6 AM to 4 PM PST Sunday for Admiralty
     Inlet-Puget Sound and Hood Canal.

     Gale Warning until 6 AM PST Sunday for Admiralty Inlet-Puget
     Sound and Hood Canal.

&&

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