Flash Flood Warning 3, NWS Seattle, WA

117 
WGUS76 KSEW 230027
FFSSEW

Flash Flood Statement
National Weather Service Seattle WA
427 PM PST Tue Nov 22 2022

WAC033-061-230145-
/O.CON.KSEW.FF.W.0003.000000T0000Z-221123T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
King WA-Snohomish WA-
427 PM PST Tue Nov 22 2022

...FLASH FLOOD WARNING FOR THE BOLT CREEK BURN SCAR REMAINS IN 
EFFECT UNTIL 545 PM PST THIS AFTERNOON FOR NORTHERN KING AND 
SOUTHEASTERN SNOHOMISH COUNTIES...

At 427 PM PST, Doppler radar indicated heavy rain over the Bolt 
Creek Burn Scar. Flash flooding is ongoing or expected to begin 
shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Bolt Creek burn scar. The debris flow can consist 
of rock, mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Heavy rain producing
         flash flooding in and around the Bolt Creek Burn Scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Bolt Creek Burn Scar.

Some locations that will experience flash flooding include...
  Skykomish and Baring.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Bolt Creek Burn Scar. Severe debris flows can also be 
anticipated across roads. Roads and driveways may be washed away in 
places. If you encounter flood waters...climb to safety.

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 4779 12151 4782 12152 4784 12150 4778 12141
      4779 12137 4777 12130 4771 12133 4771 12137
      4772 12141 4776 12147

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

33

Area Forecast Discussion
National Weather Service Seattle WA
315 PM PST Tue Nov 22 2022

.SYNOPSIS...A frontal system will exit Western Washington this
evening. Some lingering showers and breezy conditions will linger
into tonight. Dry conditions Wednesday and Thursday. Additional
frontal systems expected to move through the area Friday and this
weekend as active weather returns.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...Current radar showing back
end of the front making its way out of the Olympic Peninsula while
satellite imagery shows clearing skies over the outer coastal
waters. While the rain might be ending there, seeing some breezy
conditions develop as coastal obs sites /UIL and HQM/ are showing
wind gusts of 24 mph and 26 mph respectively. Starting to see gusts
akin to this in the south Sound area as well...so expectation for
post-frontal breezes definitely on track.

Forecast models remain in sync with most precip ending by midnight
tonight. The exception will be along the Cascades, but even by that
point activity will have begun to taper off with maybe a lingering
convergence zone in place over the central portion. As such,
inherited headlines still look good and will remain in place for
their duration. Upper level ridging moves in Wed and Thu, bringing a
return to dry conditions and cold low temps Wed night/Thu morning.

Next frontal system on Friday will bring a pattern change to what is
more typically associated with fall in the Pac NW as an upper level
low sinking southward from the Gulf of Alaska will cycle through a
number of shortwave troughs through W WA. Deterministic models agree
on a Friday morning start to precip...but cannot agree if it will be
early or late morning. Ensembles are siding with the earlier start
and that is what is reflected in the forecast.

Temps in the short term are a good news/bad news type scenario. The
good news is that daytime highs should pop into the lower 50s in the
lowlands Wed, Thu and Friday. The bad news is that Wed night/Thu
morning will be chilly with lows in the 30s. Thu night/Friday
morning will see some improvement as some locations will be in the
lower 40s, but upper 30s will also linger.  18

.LONG TERM /SATURDAY THROUGH TUESDAY/...Saturday may see a brief
lull in the action as a minor shortwave ridge quickly crosses W WA.
Deterministic models and ensembles lean toward bringing the next
frontal system into the area as early as Saturday evening...possibly
holding off until the overnight hours...as the aforementioned upper
level low reaches the northern tip of Vancouver Island. As the low
rapidly sinks further southward, reaching N OR by late Sunday
night/early Monday morning, rain will taper off as the upper low
takes the bulk of its moisture with it. Another shortwave ridge will
allow for generally dry conditions into Tuesday before another upper
level low enters the area. While it will bring another round of
precip with it, the lingering forecast question remains is if the
timing of the precip will line up with the coldest temps to allow
for lowland flakes. Models show a low degree of confidence here, so
at this time feels more prudent to suggest that while there may be a
few flakes mixed in with what should be largely liquid precip, this
is something that will need to be monitored.

Temps during the long term likely to be on a cooling trend with
daytime highs starting out in the upper 40s to around 50 on Saturday
then falling into the mid to upper 40s Sunday before reaching their
nadir both Monday and Tuesday in the lower to mid 40s. Overnight
lows Sat and Sun will remain pretty static thanks to cloud cover,
with lows in the mid 30s to around 40 while ridging Monday will
allow lows to dip down into the upper 20s to lower 30s. Tuesday sees
similar lows even though another system moves into the area.  18

&&

.AVIATION...A frontal system has moved across the region today
bringing widespread rain and showers with lowered ceilings.
Precipitation will gradually decrease into the evening but lowered
ceilings are likely to remain. MVFR categories will persist into the
overnight hours across area terminals. Can't rule out pockets out
IFR into early Wednesday morning as well. Breezy southerly winds for
terminals along I-5 will decrease into the evening. KCLM should see
breezy winds (10-20 kt) pick up into the evening before decreasing
later overnight. Southwesterly flow aloft is expected to turn more
northwesterly tonight and into Wednesday.

KSEA...Currently, IFR conditions are being observed over the
terminal as rainfalls. As precipitation pushes off and away,
ceilings should lift a bit, possibly to VFR criteria at times but
mostly MVFR skies are expected. Breezy south-southwesterly winds
should pick up in the late afternoon-evening and top out around 10-
15 kt before decreasing overnight.

&&

.MARINE...A frontal system has pushed through area waters bringing a
round of warnings and advisories. Gales have been allowed to expire
over the coastal waters but they look to persist through central and
eastern Strait of Juan de Fuca as a surge of westerly winds pick up.
This feature is on track to expire later tonight along with small
craft advisories posted for the inland waters. As we go into
Wednesday, conditions are slated to be less active as high pressure
builds into the region. A similar trend will follow into Thursday
before the next disturbance arrives towards the weekend with another
possible round of headlines.

8 to 10 ft seas are in the forecast for tonight but should fall to 6
to 8  ft around midweek. However, seas are likely to rise again
towards the weekend.

McMillian

&&

.HYDROLOGY...No river flooding is expected over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 10 PM PST this evening for West
     Slopes North Cascades and Passes.

     Winter Weather Advisory until 4 AM PST Wednesday for West Slopes
     North Central Cascades and Passes.

PZ...Small Craft Advisory until 11 PM PST this evening 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-Puget Sound and Hood Canal-
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning until 11 PM PST this evening for Admiralty Inlet-
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until midnight PST tonight for Northern
     Inland Waters Including The San Juan Islands.

&&