Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 201809 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1008 AM PST Mon Nov 20 2017

Updated the Marine and Aviation sections

.SYNOPSIS...Wet and unsettled weather will continue this week. A cold
front will move southeast across the area by midday today, then lift
north as a warm front tonight and Tuesday with some windy conditions
especially near the coast and more rain. A trailing sort of cold
front will linger over the forecast area, especially the coast and
the north interior, Tuesday night and Wednesday for more rain. Snow
levels in the Cascades will remain relatively high. The next cold
front sweeps through on Thanksgiving with snow levels in the Cascades
lowering some Thursday afternoon and Friday. Look for some lingering
showers Friday before the next system arrives on the weekend.
&&

.SHORT TERM...Today through Wednesday...The main cold front came
onshore over night and is moving east of the Cascades this morning.
The winds (especially at the coast) are decreasing and precipitation
is starting to break up, lessen, and will continue to move off to the
east through the day. Despite the cold frontal passage, snow levels
will remain high in the Cascades.

While the frontal boundary moves east and south of the forecast area
this afternoon, it will lift back to the north tonight and Tuesday as
a significant warm front. This warm front will have a good dose of
rain with it, maintain the high snow levels in the Cascades, increase
east winds through the Columbia River Gorge, and increase winds along
the coast. The strongest winds at the coast will be near beaches and
headlands, and it could be pretty windy there much of Tuesday.

While the warm front will tend to hang around near or just to our
north Tuesday night and Wednesday, a trailing pseudo-cold frontal
boundary will then hang around the area Tuesday night and Wednesday
for some rain continuing. The models indicate that the amounts will
be heaviest over the northern mountains on Tuesday night as a wave
lifts north, otherwise the amounts will tend to be less than last
night and those expected through Tuesday. Snow levels will remain
high.

The next cold front is expected on Thanksgiving.

Total rainfall amounts through Wednesday could reach 4-7 inches at
the coast and the mountains and 0.67-1.75 in the valleys. The Grays
river at Rosburg did reach flood stage early this morning but no
other rivers are expected to reach flood stage. In general, the
rainfall through the next few days is not expected to cause flooding
other than some possible localized urban flooding should leaves clog
storm drains, though area rivers and streams will likely continue to
see some sharp rises this week. Tolleson

.LONG TERM...No Changes. Previous discussion follows...
Wednesday night through Sunday...Expect steady rain across the region
during any pre-holiday travel. For Thanksgiving, a front crossing the
area will bring rain to southwest Washington and northwest Oregon,
but expect temperatures to be several degrees above seasonal normals,
with afternoon highs in the mid to upper 50s. Snow levels look to
remain well above the Cascade passes. There might be a slight break
in precipitation at the start of next weekend, but it`s looking more
unlikely as a new system enters into the area during the weekend.
Bishop/Tolleson
&&

.AVIATION...Cold front has dropped south and will hover around EUG
through the day today. That is why EUG will likely remain MVFR
through the rest of today. Elsewhere, expect improving conditions,
with most sites already VFR as showers are decreasing behind the
front. Expect VFR conditions to continue until the front down around
EUG starts to make its way back north tonight. With rain spreading
northward tonight, expect widespread MVFR cigs and/or vis to return
and continue into Tuesday morning.

KPDX AND APPROACHES...Showers coming to an end this morning. Expect
VFR conditions to continue through this evening. Cigs and/or vis will
lower to MVFR as the next system brings rain into the terminal around
09Z tonight. -McCoy
&&

.MARINE...Winds and seas are subsiding this morning as the front has
dropped south of the area. Will see a period later today where seas
should be around 8 to 9 ft and winds below 20 kt, though seas have
been slow to subside this morning. The front that dropped south of
our area earlier this morning will stall and remain fairly stationary
south of our waters today, but start to make its way back northward
late tonight. This will bring gales back to our waters beyond 10 nm
from the coast, and 25-30 kt winds to our inner waters with a chance
for a few gusts to 35 kt. This will also build seas back up on
Tuesday into the mid-teens, peaking Tuesday evening when we could see
seas top out at 16 to 17 ft.

We remain in an unsettled pattern with a series of systems moving
south to north offshore Wednesday and Thursday, bringing additional
chances for gale force winds in our outer waters beyond 10 nm from
the coast. This will keep seas up into the low-to-mid teens through
Thursday. May get a bit of a break on Friday, then another system
moves up the coast this weekend.  -McCoy
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds until 10 AM PST this morning for
     Coastal Waters from Cape Shoalwater WA to Florence OR out
     60 NM.

     Gale Warning from 4 AM Tuesday to 3 AM PST Wednesday for Waters
     from Cape Shoalwater WA to Cascade Head OR from 10 to 60
     NM.

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

     Gale Warning from midnight tonight to 3 AM PST Wednesday for
     Waters from Cascade Head to Florence OR from 10 to 60 NM.

     Small Craft Advisory for Rough Columbia River Bar until 4 PM
     PST this afternoon.

&&

$$

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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 CWA, or forecast area.



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