Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Seattle Washington
330 PM PDT sun Mar 9 2014
Synopsis...an upper level trough will move through the area tonight
into Monday morning for a few more showers. An upper level ridge
will then build over the area Monday night providing dry and mild
weather through Thursday. A weak system will clip the area Thursday
night or Friday. The ridge may rebuild over the area on Saturday.
Short term...heavy rainfall on Sat/Sat night forced several rivers
into flood stage early this morning. An upper level trough will
shift inland tonight for a few more showers...although these showers
will not be hydrologically significant. The rivers that have crested
will continue to recede. Additional flooding is not expected.
An upper level ridge will build offshore on Monday with the flow
aloft turning northwesterly. Models show showers mainly over the
interior and the Cascades. Showers will taper down Monday night as the
ridge starts to shift inland.
High pressure will bring dry weather to western Washington Tuesday and Wednesday. We
should see highs in the 50s to lower 60s on Tuesday. Wednesday will be a few
degrees cooler as the ridge flattens a bit and the surface flow
turns onshore. 33
Long term...both the GFS and European model (ecmwf) maintain a ridge over the Pacific northwest
on Thursday for another dry/mild day for western Washington. Highs will
be mainly in the 50s. A weak upper level disturbance will then move
into b.C. Late Thursday night and Friday with a few showers across western
Washington...mainly northern part. The ridge may rebuild over the region on
Sat. The models then show an upper level short wave trough clipping
through western Washington sun or Sun night. 33
Hydrology...several rivers reached flood stage this morning and
flood warnings are still in effect as the rivers are running high.
The Flood Watch will be trimmed down to just Thurston and Grays
Harbor counties as we wait for the Chehalis to crest.
Otherwise...heavy precipitation has ended and the rivers will recede. 33
Aviation...an upper trough offshore will move across the region late
tonight or early Monday. An upper ridge will follow on its heels.
Strong westerly flow aloft will become light overnight. A weak surface
trough offshore will dissipate as it approaches the coast tonight.
Light low level onshore flow will strengthen somewhat on Monday.
Areas of ceilings in the 1-3k feet foot range will persist through tonight.
Expect isolated ceilings below 1k feet and visibilities in the 1-3sm range...
mainly due to fog. The mountains will be mostly obscured.
Ksea...VFR conditions are expected through this evening. Expect
occasional ceilings in the 2-3k feet range after 0600 UTC Monday.
a weak surface trough will move across the coastal waters tonight
but will dissipate before moving inland. Building high pressure offshore
and lower pressure east of the Cascades will result in increased onshore
flow on Monday. The flow will become flat on Tuesday in response to a
surface high settling over the area. Light onshore flow will return
Washington...flood watches and/or warnings are in effect for parts of the
County Warning Area.
Pz...Small Craft Advisory in effect for hazardous seas until
midnight tonight for the coastal waters.
Small Craft Advisory in effect for rough bar until 2 am
Monday for the Grays Harbor bar.
Small Craft Advisory in effect from 7 am to 9 PM Monday for
the central and eastern Strait of Juan Delaware fuca.
For the graphical afd...visit