Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service Seattle Washington
955 am PST Sat Mar 8 2014
Corrected first sentence in the marine segment.
Synopsis...another strong frontal system will affect western
Washington today into Sunday morning with rain...high snow
levels...and locally windy conditions. An upper trough will move
through on Monday for cooler showery weather. A strong upper ridge
will provide dry and mild weather Tuesday and Wednesday.
Short term...a wet Pacific frontal system will spread more rain
through western Washington today and tonight...and rain will be heavy at
times. This system has remnants of Typhoon Faxai embedded in the
flow and looks fairly juicy on satellite. Cloud tops are cooling on
the infrared with a long plume of moisture stretching well offshore. All
this moisture will train over western Washington during the next 24 hours.
Models continue to show heavy precipitation in the mountains with 2-4
inches expected through Sunday morning. Periods of heavy rain will
force sharp rises on the rivers...which are already running high
from recent heavy rain. Precipitation will mainly fall as rain in the
mountains with high snow levels - over 7000 feet in the central
Cascades and Olympics. A Flood Watch remains in effect for portions
of western Washington. Expect heavy rain in The Lowlands as well with 1-3
inches along the coast...and up to 1 inch in the interior. It will
be windy at the coast and north interior too with south winds of 20
to 30 gust 40 miles per hour.
The baroclinic band will push out of western Washington Sunday morning with
rain turning over to scattered showers. We may see a pscz develop
over Snohomish County Sunday afternoon. The trailing upper level
trough will bring a few more showers to western Washington Sun night.
High pressure will start to build inland on Monday with drier weather
Long term...previous discussion...after a record wet start to March
a Little Break in the precipitation looks to be in store for the
area with an upper level ridge building off the coast Tuesday and
surface high pressure building into western Washington. Upper level
ridge axis moves inland Tuesday night into Wednesday with the low
level flow turning offshore keeping dry weather in the forecast for
Wednesday. Extended models continuing with the trend of push the
upper level trough further north for Thursday. Will stay with chance
probability of precipitation for now but there is certainty a chance the area could see
three dry days in a row. Upper level ridge well to the east by
Friday with a well organized system moving into the area later
Friday into Saturday. Temperatures will remain near normal through
the period. Felton
Hydrology...a Flood Warning continues for the Skokomish River at
Potlatch for minor flooding. The river fell below flood stage last
night but with the possibility of 3 plus inches of rain in a 12
hour period later today into tonight for the south slopes of the
Olympics the river is forecasted to rise back above flood stage
Moderate rain with a few hours of heavy rain are expected on later
this afternoon into tonight with snow level 7000 to 8000 feet
leading to renewed rises on all area rivers. Currently the only
Flood Warning is for the skokomish but the more flood prone rivers
like the Puyallup at Orting will need to be watched. Other rivers
that came close to or did go over flood stage this last round like
the Cowlitz at Randle and the Snoqualmie at Carnation also bear
Aviation...an upper trough offshore will continue moving east and will
move across the area late tonight or early Sunday. Strong westerly flow
aloft. A cold front well offshore will sweep across the area tonight.
Increasing low level southerly flow today. Expect ceilings will lower into
mainly the 1-3k feet range today. There will also be areas of visibilities in
the 2-5sm range due to rain and fog this afternoon.
Ksea...anticipate ceilings to lower to near 3k feet this afternoon. Winds
will pick up out of the S or SW at 10-15 knots this evening and there
will likely be occasional gusts near 25 knots.
a strong cold front offshore will move across the area tonight. The
strongest winds are expected to occur during this afternoon through
early evening. Expect light onshore or westerly flow to prevail in
its wake Sunday and Monday.
Washington...flood watches are in effect for much of the County Warning Area.
Pz...gale warnings are in effect for the coastal waters...
entrances to the Strait of Juan Delaware fuca...and the northern
Small Craft Advisory in effect for the remaining waters.
Small Craft Advisory in effect for rough bar until 5 PM PDT
Sunday for the Grays Harbor bar.