677
FXUS66 KPQR 270322 AAA
AFDPQR

Area Forecast Discussion UPDATED
National Weather Service Portland OR
820 PM PDT Fri Jul 26 2024

...EVENING UPDATE, for aviation weather.

.SYNOPSIS...Stable onshore flow will maintain fairly benign
weather with seasonably warm days and cool nights through early
next week. A passing system brings a chance for rain next Monday
into Tuesday. Models then hint at a warming trend mid to late
next week as high pressure builds back over the area.

&&

.SHORT TERM...Tonight through Sunday Night...Typical summer weather
today and through the weekend. Broad, weak troughing aloft with
stable westerly flow across the region. Some light haze from nearby
wildfire smoke, mainly east of I-5 will push t 5-10 kt with gusts up
to 18 kt lasting until 05-06Z Saturday. back east of the Cascades
tonight as another surge of onshore flow moves across the area. The
main exception will be where near surface smoke is confined to the
immediate vicinity of ongoing fires in the Linn and Lane County
Cascades where LRAPA has issued an Air Quality Advisory through
Saturday afternoon. Afternoon highs expected in the lower to mid 80s
for the interior lowlands. Morning clouds from marine layer
intrusions into the inland valleys each night will help moderate
overnight temps a few degrees. Otherwise, mostly sunny skies
continue through Sunday. Breezy conditions will continue through the
central Columbia River Gorge Saturday and Sunday afternoon and
evening, with a renewed onshore push perhaps allowing for slightly
stronger winds gusting to around 25-35 mph in parts of Hood River
County. /DH

.LONG TERM...Monday through Friday...Still monitoring chances for
rain early next week. Models continue to speed up the timing of the
frontal system as a more well defined shortwave embedded within the
large scale trough crosses the region. Rain is likely to begin as
early as Monday morning for coastal areas, gradually spreading
inland through Monday night. PWAT values peak Monday afternoon
around 1.5 inches of precipitable water according to the ECMWF
ensembles. Regardless, ensemble and probabilistic guidance continue
to be rather bullish on the prospect of at least measurable rain
across the area, depicting around a 70 percent chance for northern
coastal areas and about a 50/50 shot for the Willamette Valley.
Meanwhile, the chance for as much as a quarter inch of rain sits
around 40-50 percent on the coast and 20-25 percent from Eugene to
Portland. Also expect slightly cooler temps again Monday into
Tuesday as this system crosses the region accompanied by increased
cloud cover and highs closer tot he upper 70s in the inland valleys.

WPC ensemble clusters continue depict a ridge of high pressure
developing over the western CONUS and a subsequent warming trend
mid to late next week. Guidance has backed off slightly for
highs next Wednesday, keeping temps closer to the mid 80s for
one more day before the chances to reach 90 degrees jump up to
around 70-80 percent in the inland valleys by Thursday and remaining
there through the end of next week. DH/CB

&&

.AVIATION...Dry west to northwest flow aloft over the region. High
pressure  offshore will maintain low level onshore flow into Sat. As
such, will see areas of MVFR CIGS reforming along the coast over
rest of Fri evening, with that stratus pushing inland via the gaps
in the coastal mtns/highlands. Should see areas of lower MVFR inland
throughout the Cowlitz River Valley, and along the Columbia River
upstream to the PDX/VUO/TTD area by 12Z to 13Z. But, inland stratus
will gradually break up Sat am, with mostly clear skies afterwards.
Stratus along the coast will persisting into the early afternoon,
then gradually break apart, with scattered clouds in the afternoon.

With westerly to northwest flow relaxing overnight, will maintain to
see haze and smoke over and east of the Oregon Cascades. Expect some
reductions to slantwise visibilities, along with smoke layers around
the fires.

PDX AND APPROACHES...VFR will continue, with dry air mass and mostly
clear skies. But, with onshore flow, will see areas of MVFR marine
stratus pushing up the Columbia River overnight, spreading across
Clark County by 12Z, and into OPS area from 13Z to 17Z, mainly east
of Interstate 5 to the Cascades foothills.               /Rockey

&&

.MARINE...A weak upper level trough will slowly meander eastward
through the weekend. Currently, expect persistent north/northwest
winds with low-end Small Craft gusts, primarily in our central
and southern waters. Threat will subside late tonight (Friday) and
seas will remain around 4 to 6 ft thereafter. Overall benign
conditions through the weekend with a southerly wind shift
expected late Sunday/early Monday.
-JH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 2 AM PDT Saturday for PZZ252-253-272-
     273.
&&

$$

www.weather.gov/portland

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