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fxus66 kpqr 241052 

Area forecast discussion
National Weather Service Portland or
251 am PST Fri Nov 24 2017

Synopsis...a series of fronts will continue periods of wet weather
into next week. Snow levels will be near the Cascade passes
but with light precipitation and minimal snow accumulations at pass
levels. Showers diminish for today through early Saturday, but rain
returns under a weak warm front Saturday afternoon and night. A cold
front crosses Sunday bringing a better chance for snow to impact the
passes Sunday and Monday.


Short through Sunday...a cooler air mass will be in
place behind a cold front that moved through Thu. Cloud breaks
are allowing radiational cooling and spots of fog to develop inland.
Weak shortwaves embedded in the swly flow aloft will keep moisture
streaming into western Washington today. This will result in a chance of
showers for the north coast and north inland zones. Most of the
remainder of the County Warning Area will be dry, except for a few orographic
showers. Higher pressure aloft builds tonight, lowering chances for

A stronger upper shortwave will approach from the southwest on Sat.
The associated surface low will deepen to around 985 mb Sat afternoon
as it tracks north along 130w off the north Oregon coast. A warm
front will brush the area with rain Sat afternoon and should be north
of the area Sat night. The County Warning Area will be in the warm sector ahead of
the cold front for relatively mild Sat evening. The cold front will
spread rain to the coast Sat evening and inland late Sat night. It
will move across the area Sun morning. Snow levels remain above pass
levels crossing the Cascades, then lower closer late Sun afternoon
for some light accumulations.

There is a chance for a burst of gusty winds along the coast and
coastal mountains as the low moves north along the coast Saturday
evening. /Mh

Long term...Sunday night through Thursday... a colder upper level
trough will support snow levels staying near the Cascade passes with
showers over the region Sunday night and Monday. The models
vary on how quickly the upper trough will move east, but generally
agree that an upper ridge will replace the upper trough Monday night.
As monday's upper trough advances into the Great Basin and plains,
models remain in reasonable agreement and suggest rising heights
across the Pacific northwest into Tuesday. This may bring a bit of a
break in the precipitation, though there is some hint that the
northern extent of the forecast area (primarily north of a Tillamook
to Mt. Hood line) may be clipped by a front associated with a low
moving into central b.C. As a result, have lowered pops across the
southern and southeastern portions of the forecast area. Models then
diverge more significantly as we move into the second half of next
week, so have held the forecast closer to climatological normals.


Aviation...stable southwest flow aloft, with variable mid and
high clouds over the region today and tonight. May see a few
isolated showers, but overall will be dry. Just enough clearing
that will continue to see pockets of low clouds and fog, mainly
over the interior. Clouds will thicken along the coast later in
the day, with mostly VFR but pockets of MVFR cigs possibly to
north of ktmk.

Kpdx and approaches...generally VFR today and this evening. While
not much, will see patchy fog or low clouds in/around the Ops
area until 18z today. Rockey.

Marine...more benign weather on the coastal waters today into
Saturday. High pres remains well inland, with lower pres well
offshore. This will maintain south to southwesterly winds on the
waters today, with 10 to 20 kt. But, enough gradient over the
outer waters that will see gusts up to 25 kt at times. Will
expand Small Craft Advisory for winds to cover all outer waters
for today through Sat am. Seas mostly 7 to 9 ft, but with bit
more wind over the outer waters, seas will range from 9 to 11 ft
over the outer north waters. Will maintain Small Craft Advisory
for that area through Sat.

Low pres will approach the region from the SW on Sat. This will
turn winds more southeasterly. Models continue to show the low
staying well to west of the region as it moves north towards
west tip of Vancouver Island Sat night. But, cold front will
swing east across the coastal waters Sat night into sun am. Winds
will increase, but generally stay southeasterly until just ahead
of the front, then will turn hard south. Reasonable confidence
that will have solid southerly gales, with strongest winds
between midnight and 6 am sun. Gale watch remains in effect for
Sat afternoon through sun on the outer waters, but will likely
include the inner waters later Sat night as front draws closer.
Seas will build Sat night, with 15 to 22 ft on the outer waters
with the stronger winds, and 14 to 17 ft on the inner waters.

Another weaker system looks pass south of the region on Mon.
Then looks more tranquil over the region as high pres builds over
the region. If current trends continue, could see northerly
winds 10 to 15 kt for good part of next week.


Pqr watches/warnings/advisories...


Pz...gale watch from Saturday afternoon through Saturday night
Cape Shoalwater to Florence, from 10 to 60 nm offshore.

Small Craft Advisory for winds today through Sat afternoon
Cape Shoalwater to Florence, from 10 to 60 nm offshore.

Small Craft Advisory for hazardous seas until 1 PM Sat for
Cape Shoalwater to Cascade Head, from 10 to 60 nm.



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