Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 241647

Area Forecast Discussion
National Weather Service Portland Oregon
935 AM PDT Mon Oct 24 2016

.SYNOPSIS...Strong low pressure well off the Oregon and Washington
coast with an associated cold front trailing back along the coast.
This front will move slowly onshore across the area today. Showers
will develop in the unstable air behind the front. This system will
bring gusty S-SE winds and large surf to the coast today through
Tuesday. The broad low will weaken and lift north Tuesday, but
another low is likely to take its place Tuesday night and Wednesday.
This next low will push a warm front across the region from the
south Tue night/Wed bringing more significant rainfall. Gusty winds
will likely accompany this system along the coast on Wednesday. The
area will remain under the influence of a broad upper trough with
generally wet and showery weather throughout the week.


.SHORT TERM...Today through Wednesday...Satellite imagery shows a
well developed nearly vertically stacked 969mb low pressure system
centered about 265 miles west of Astoria very near buoy 46005. The
low is moving to the north and has become a bit more disorganized
during the past several hours, but is still much more organized than
the low of October 15. Today`s low is much farther offshore but the
strong gradients extend further out than the Oct 15 system. As the
occlusion wraps back around the low this afternoon the gradient over
the Oregon and South Washington coastal waters will strengthen some
with increasing south winds. The strong easterly gradients over the
coast will help confine the strongest winds to the waters and not
generally over the coastal communities. Still, it will be windy
along the coast today and early this evening.  Expect a few higher
gusts at the exposed headlands, otherwise impact should not be too
great and for now we will not have any warnings for high wind over
the land. At this time we expect the northward motion of the low to
continue as the the system begins to slowly weaken later this

Winds over the inland valleys are not expected to be a real problem
today as not significant north south gradient developer, but it will
be a breezy. Gusty east winds will continua through he Columbia
Gorge and extending into the east Portland Vancouver metro area
today as a result of the strong easterly gradients which have
weakened a bit during the past few hours, but should increase later
this afternoon.

The cold front is beginning to push onshore spreading rain inland by
afternoon. The front will be followed by cooler air aloft and since
it is fairly warm at the surface and there is a good amount of
vertical shear a few thunderstorms are expected to develop over the
waters and along the coast. Schneider

.LONG TERM...Wednesday night through Sunday...A complex weather
pattern continues offshore late in the week into next weekend. The
low that will bring rain to the area Wednesday moves north Wednesday
night and brings a cold front across the region on Thursday. The low
then moves inland as an open trough Thursday night as two other
Pacific lows move into the offshore waters. One low approaches from
the south, and another larger low approaches from the northwest. This
will result in dry weather for the Portland forecast area Thursday
night. The northern low deepens over the ne Pacific Friday allowing
an upper ridge to amplify over the Pacific NW, and keeping the
southern low south of northwest Oregon. The southern low moves inland
across north California and east Oregon Friday or Saturday for
showers over the Portland forecast area. The second low then moves
onshore on Sunday for a continued threat of rain. Snow levels will
remain well above the Cascade passes. TJ


.AVIATION...Rain spreading inland today as a weak front moves in.
Still expect primarily VFR conditions though over the interior, with
just a 10 percent chance of MVFR conditions through 03z this
evening. Along the coast there was a mix of VFR and MVFR conditions
this morning. Expect to see primarily VFR conditions along the coast
this afternoon after 19z. A chance for MVFR cigs with post frontal
showers returns tonight, mainly after 05z. Gusty east winds continue
near the Columbia River Gorge through this afternoon. Gusty
southerly winds expected along the coast mainly after 18Z, with
gusts to 30 kt likely.

KPDX AND APPROACHES...Primarily VFR with cigs lowering to 5000 ft
this afternoon. Light rain expected after 18Z, but with no
significant impact to flight conditions.


.MARINE...Strong southerly winds across the waters today, will be
strongest over the outer waters as a deep low pres system around
969mb moves slowly north near 131w. The low will move from off the
WA coast today, weakening tonight and Tuesday and eventually moving
north of 50n Tue afternoon. Will continue with gale warning today
into Tuesday morning, with the nearshore waters last to see to gales
developing this afternoon. May see peak gusts flirting with 50 kt
tonight, mainly over the outer waters, but at this point expect any
storm force gusts to be isolated. Seas will build today into tonight
with the slow moving low, with current expectations for peak seas to
reach near 25 ft over the outer waters tonight, with slightly lower
peak heights near the coast due to the southerly fetch.

Another low, a bit weaker, is expected to move north off the OR and
WA coast near 130w Tue night and Wed. Gale force winds will be
possible with this system as well, most likely Wed over the
outer waters.


PZ...Gale Warning until noon PDT Tuesday for Waters from Cape
     Shoalwater WA to Florence OR from 10 to 60 nm.

     Small Craft Advisory for winds until noon PDT today for Coastal
     Waters from Cape Shoalwater WA to Florence OR out 10 nm.

     Gale Warning from noon today to noon PDT Tuesday for Coastal
     Waters from Cape Shoalwater WA to Florence OR out 10 nm.

     Small Craft Advisory for Rough Columbia River Bar from noon
     today to noon PDT Tuesday.



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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. The area is
commonly referred to as the forecast area. is the U.S. government's official web portal to all federal, state and local government web resources and services.