High Wind in Oregon, January 23, 2019

Area Forecast Discussion
National Weather Service Portland OR
300 AM PST Wed Jan 23 2019

.SYNOPSIS...After some lingering light rain and drizzle today, high
pressure building over the northeast Pacific will likely bring dry
weather and mild temperatures into at least early next week.

&&

.SHORT TERM...Today through Saturday...A shortwave trough moving
across Washington state pushed a frontal rain band southeastward
across the area overnight. This band of steadier rain has shifted
southward into southwest Oregon where it will stall and dissipate in
place over the next 12-24 hours. Farther north, very gentle
isentropic lift along the 285K-290K surfaces will lead to areas of
drizzle and light rain through at least this morning across the
area. Thereafter, shortwave ridging slowly shifts towards the
region, which should result in the area beginning to dry out late
this afternoon and evening.

Low clouds may be stubborn to dissipate entirely tonight, though. In
areas that clear, areas of fog should develop quickly. Fog and low
clouds should gradually clear Thursday and give way to high
temperatures near to slightly above average for the date. Models
then suggest a shortwave trough dropping southeastward across the
Inland Northwest will likely bring a brief increase in clouds and
winds to the higher terrain late Thursday. There is an outside
chance of light rain across our far northern zones, but the bulk of
the area will almost certainly remain dry.

Shortwave ridging will then become more solidly entrenched across the
Pacific Northwest Friday and Saturday. This should result in areas of
valley morning fog and mild temperatures. Weak offshore flow on
Saturday may result in the central Oregon coast and portions of the
Coast Range and Cascade foothills warming well into the 60s on
Saturday. Thinking morning low clouds and fog will keep temperatures
from warming too much in the Willamette Valley, though. /Neuman

.LONG TERM...Saturday night through Wednesday...Operational models
and their ensembles are in good agreement a large ridge of high
pressure will more or less continue across the northeast Pacific into
early next week. This will produce a multi-day stretch of dry
weather, initially mild temperatures, and areas of late night and
morning valley fog. It should be noted that models are also coming
into agreement a shortwave trough diving southward out of Canada will
push cooler air into the Columbia Basin and turn the flow more
solidly offshore Sunday night into Monday. At this point, models
suggest a modest downslope wind event, but will need to monitor this
in the coming days. Otherwise, operational models suggest it will
remain dry through the middle of next week, but there are some
ensemble members that suggest rain chances begin to increase. As a
result, kept slight chance PoPs in the forecast for late Tuesday and
Wednesday to account for the uncertainty. /Neuman

&&

.AVIATION...A cold front moving onshore brought a band of
steadier precipitation and gusty southerly winds through the
region overnight. The rain band has now moved south into Lane
County and will dissipate over the next couple of hours. Winds
will also gradually subside over the next few hours. Expect
widespread light rain to continue this morning, then become
increasingly confined to the higher terrain this afternoon and
tonight. The low level moisture that accompanied this front has
brought steadily deteriorating conditions this morning, with
current observations showing mainly IFR at the coast, with
predominantly MVFR over the interior. Expect little change
through the day, although cigs may lift a bit in the afternoon.
The latest model soundings show that the low stratus may just
persist through tonight. If any clearing does occur late today or
tonight, it would almost certainly result in fog formation
overnight.

KPDX AND APPROACHES...Expect MVFR cigs through most of today.
Light rain and gusty southerly winds should gradually decrease
through the day. MVFR may end up persisting through tonight.
However, if any scattering in the clouds occurs this evening,
there is potential for IFR fog overnight into Thu morning. Pyle

&&

.MARINE...A cold front moving through the waters will push
onshore this morning. There are still some gusts around 35 kt
being reported over the northern waters, so will hold on to the
existing Gale Warning through 4 AM. Winds will subside fairly
quickly behind the front and should be westerly at 15 kt or less
by early this afternoon. High pressure will then begin to build
over the waters tonight and remain in place through the rest of
the week and much of the weekend. This will result in light winds
for the next few days. Winds will become northerly and
potentially gusty later in the weekend and into early next week.

Seas will remain in the low to mid teens through most of tonight.
A longer period swell will be arriving this morning that should
push dominant periods to around 14 to 15 seconds. Seas will
subside gradually tonight and should be back below 10 ft sometime
on Thu morning. Then seas will remain in the 7 to 8 ft range
through the rest of the week and into next weekend. Pyle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Gale Warning until 4 AM PST early this morning for Coastal
     Waters from Cape Shoalwater WA to Cascade Head OR out 60
     NM.

     Small Craft Advisory for winds until 7 AM PST this morning for
     Coastal Waters from Cascade Head OR to Florence OR out 60
     NM.

     Small Craft Advisory for hazardous seas until 4 PM PST this
     afternoon for Coastal Waters from Cascade Head OR to
     Florence OR out 60 NM.

     Small Craft Advisory for Rough Columbia River Bar until 10 PM
     PST this evening.

&&

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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the forecast area.