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fxus66 kpqr 161801 

Area forecast discussion
National Weather Service Portland or
1101 am PDT Mon Sep 16 2019

Updated aviation and marine sections

Synopsis...showers and isolated thunderstorms are expected today as
a cool upper trough moves over the Pacific northwest. A cold front will
bring rain and breezy winds to the area on Tuesday, with rain being
heavy at times. Another cool upper trough will continue showers and
bring another threat for isolated thunderstorms on Wednesday. Drier
weather expected late in the week, but temperatures will remain
cooler than usual for this time of the year.


Short through Thursday...isolated thunderstorms are
reaching the coast early this morning as a cold upper trough
approaches the Pacific northwest as isolated to scattered showers cs inland.
The threat for isolated thunderstorms remains on the coast through
the morning, then shifts inland this afternoon as the upper trough
moves inland. The showers will pick up in frequency and intensity
this afternoon as the cool upper trough moves over the region. The
snow levels will lower to around 6500 feet today for a light dusting
of snow in the higher Cascades, but do not expect any winter weather
for the Cascade passes.

Another strong and moist cold front will bring another round of
moderate to heavy rain on Tuesday. The rain will reach the coast
early Tuesday morning and spread inland by the early afternoon. This
front is very similar to the one that moved through on Sunday, and
expect similar rain rates and totals. Rain totals along the coast and
higher terrain of 0.75 to 1.5 inches are expected between Tuesday
morning and Tuesday evening with 0.5 to 0.75 inch expected for the
interior valleys. Winds will be breezy with the front passage on
Tuesday with gusts of 40 mph possible along
the coast and 30 mph for the Willamette Valley. Temperatures will be
much cooler on Tuesday with daytime highs barely making it to 60

Another cool upper trough follows the Tuesday front that will support
showers through Tuesday night and Wednesday. Cold air aloft will
destabilize the atmosphere and expect isolated thunderstorms along
the coast Tuesday night and inland Wednesday afternoon. The upper
trough moves east of the Cascades Wednesday night and showers will

An upper ridge tries to build on Thursday, but a shortwave trough may
sneak over the ridge and maintain Cascade showers or marine stratus
and drizzle along the coast. Regardless it will be a drier day.
Temperatures will warm a bit, but still be well below the seasonal
normals. ~Tj

Long changes. Previous discussion follows...Thursday night
through Sunday...cannot rule out that some stray showers will
continue into Friday as weak disturbances move through the upper
level flow. There remains quite a bit of uncertainty in the weather
towards the end of the week and into next weekend. At this juncture,
looks like late Friday and Saturday could be fairly dry, then another
upper level trough approaches the region on Sunday bringing a chance
of showers. /Tw


Aviation...isolated thunderstorms continue over the coastal
waters this morning, with some approaching the coastal terminals.
With some even reaching the coast. Chances for thunderstorms will
spread inland today through the evening with a mix of VFR and MVFR
conditions expected through the day as widespread showers continue.
Meanwhile, next front approaches tonight, bringing strong south
winds across the region after 09z coast and 12z inland, along with
likely MVFR (or lower) cigs/vsby under moderate to heavy rain on

Kpdx and approaches...mostly VFR conditions though scattered MVFR
deck may occasionally solidify into MVFR ceiling. Otherwise, showers
expected to increase this afternoon, with occasional MVFR (or
possibly ifr) conditions and/or a thunderstorm possible through
around 04z. Gusty south winds develop after 12z ahead of approaching
front, with moderate rain bringing solid MVFR Tuesday morning. Cullen


Marine...a broad surface low will slide south across the coastal
waters today. Winds generally around 15 kt, though showers and
thunderstorms could bring stronger gusts and variable wind
directions at times. Seas generally hold around 9 feet through this

The next front will likely bring gale force winds to the waters
after midnight tonight through at least midday Tuesday. Current Gale
Warning remains on track with a burst of stronger winds expected
early Tuesday morning, likely peaking around 35 to 40 kt. Meanwhile,
expect combined seas to build to around 12 feet and largely
dominated by a steep, wind-driven component.

Winds settle Tuesday night into Wednesday with broad low pressure
over the waters, but seas stay in the 8 to 10 ft range with northwest
swell. High pressure returns to the waters late in the week for a
return of a northerly wind pattern.


Pqr watches/warnings/advisories...
Pz...Gale Warning from 3 am to 2 PM PDT Tuesday for coastal waters
from Cape Shoalwater Washington to Florence or out 60 nm.



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