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Area forecast discussion 
National Weather Service Medford or
534 am PST sun Jan 25 2015

Update...the forecast was updated to issue a dense fog advisory
for west side valleys this morning. The ridge and thus also the
inversion are at peak strength over the area with areas of near
zero visibilitiy through 10 am PST. Similar to yesterday, the
shallowness of the inversion layer should allow the low clouds and
fog to dissipate and give way to a sunny afternoon.

&&

Previous discussion... /issued 330 am PST sun Jan 25 2015/

Discussion...there is little change in the weather pattern today
and Monday. A very strong ridge of high pressure will persist
along the West Coast leading a stagnant airmass with strong
inversions overnight through late morning. Expect another rapid
drop in visibility around sunrise and areas of dense fog is
possible again this morning. Just off the Baja California peninsula there is
a closed low pressure that is forecast to spin to the NE into
Southern California. The main effect will be to weaken and shift
the ridge slightly east on Tuesday..while letting upstream trough
to move into the Pacific northwest. This may help loosen the grip on the
air stagnation a bit but most of the energy from this trough will
be heading toward Washington and northern or. We may see some light rain
at the Coos County coast and Douglas County with mainly more
clouds elsewhere in Oregon. Another area that may see light
showers on Tuesday in northeast California where the remnant of
the closed low is forecast to track into Nevada.

Both the GFS and the European model (ecmwf) brings the ridge brings the ridge back
into our forecast area from Thursday through next weekend. /Fb

Aviation...based on the 25/06z taf cycle...VFR conditions will
continue over much of the area through Sunday. Stratus and fog with
LIFR ceilings and visible will develop in the west side valleys in the very
early morning to dawn Sunday and continue through middle morning before
burning off. Fog with MVFR visible has already formed over parts of the
coast (including koth) and is expected to gradually lower through
the night. However, offshore flow is expected to increase and may
drive the fog offshore early Sunday morning. Moisture is a little
higher than last night on the east side, so fog is slightly more
likely tonight, but confidence remains low. -Wright/bpn

Marine...updated at 800 PM Saturday 24 January 2015...weak high
pressure will remain over the waters through the weekend with steep
seas dominated by a long period west swell. Winds will become south
on Sunday night and remain light to moderate while seas diminish
Monday into Wednesday. A weak front is forecast to brush across the
waters on Tuesday with a slight chance of showers. High pressure
will follow with light to moderate northerly winds developing on
Thursday. -Wright/bpn

&&

Mfr watches/warnings/advisories...
or...air stagnation advisory until 11 am PST Tuesday for
orz023-024-026-616-620-622.
Dense fog advisory until 10 am PST this morning for
orz023-024-026-616-617-620-622.
Air stagnation advisory until 11 am PST Tuesday for
orz029>031-623>625.

California...dense fog advisory until 10 am PST this morning for caz080-280.

Pacific coastal waters...Small Craft Advisory for hazardous seas
from 4 PM this afternoon to 10 PM PST this evening for
pzz350-356.
Small Craft Advisory for hazardous seas from 10 am this
morning to 10 am PST Monday for pzz370-376.

$$

Fjb/fjb/dw

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