114
FXUS66 KPQR 190505
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
1005 PM PDT Wed Sep 18 2024

.UPDATED AVIATION DISCUSSION...

&&

.SYNOPSIS...
High pressure returns, bringing dry weather with
near to slightly below normal temperatures through the end of
the week. Another front will bring a chance of showers Sunday
into Monday. Warmer and drier conditions possible next week,
however some uncertainty remains with the weather pattern.

&&

.SHORT TERM...Now through Friday Night...Satellite imagery and
surface weather observations as of early Wednesday afternoon
depict dry conditions with lingering scattered/broken clouds as
yesterday`s upper level trough exits the region. As high
pressure re-builds over the NE Pacific and Pacific Northwest,
expect decreasing clouds through the early evening. Winds will
be out of the north/northwest with the strongest gusts (up to 20
mph) through the Columbia River Gorge. High temps this
afternoon will re-bound into the low to mid 70s for interior
lowland valleys (slightly below normal) and mid to upper 60s
along the coast.

Expect dry weather with mostly sunny skies Thursday to Friday
as high pressure remains over the area. Light to moderate
onshore flow continues, with the strongest gusts again through
the Gorge and Upper Hood River Valley area. Each night, could
see some patchy fog development along with low clouds overnight
into the early morning hours. Low temperatures are forecast in
the 40s to mid 50s, with afternoon high temps similar to today.
Overall, we`ll have pleasant days to end the week.     -Alviz


.LONG TERM...Saturday through Wednesday...Lingering
uncertainty this weekend into the early part of next week as
medium and long range guidance continues to diverge with respect
to how the pattern will evolve beyond Friday. That said,
ensemble clusters have started to slightly favor a warmer and
drier pattern for Saturday and beyond, with about two thirds of
solutions now indicating a ridgier pattern while the other third
still depict troughing or more zonal flow. As a result, NBM
interquartile ranges for temperatures have narrowed to show
inland high temperatures most likely residing in the mid to
upper 70s Saturday through Monday. Precipitation chances have
also gone down as models hint at upper level ridging, but NBM
mean guidance still carries chance to slight chance PoPs across
mainly the northern half of the area late Sunday into early
Monday, which reflects the below normal forecast confidence.
Model agreement actually increases towards the beginning of next
week as ensemble clusters show about 90 percent of solutions
favoring some degree of upper level ridging over the Pacific
Northwest for Monday and Tuesday. As such, Tuesday looks to be
the warmest day in the next week with highs possibly reaching
into the mid 80s in the interior valleys. Models start to
diverge again beyond Tuesday as guidance is split between
another trough and a more gradual breakdown of the ridge. /CB

&&

.AVIATION...Northeast flow aloft as upper ridge of high pressure
gradually builds over the region headed through Thursday. Stratus
has already begun to build along the coast with conditions likely
(60-80%) deteriorating to IFR tonight into Thursday morning.
Stratus also likely (40-80%) back-builds off the Cascade
foothills towards the inland terminals after 10-12z Thursday with
MVFR CIGs trending toward 1500-2000 ft - highest likelihood at
PDX and TTD. Fortunately any low status inland will dissipate
around midday. Generally expect north to northwest winds,
increasing during the afternoon.

PDX APPROACHES...Predominately VFR expected through the overnight
hours as broken stratus has lifted to around FL040-050. MVFR
stratus likely (70-90% chance) redevelops after 12z Thursday
before breaking up around 18z. Expect northwest winds to around
6-8 kt Thursday afternoon. -Schuldt/DH

&&

.MARINE...High pressure has returned to the coastal waters,
resulting in increased northerly winds today, likely continuing
through the week. Winds may gust up to 20-25 kt at times
tonight, especially over the outer coastal waters. Wind gusts to
25 kt becomes more likely by Thursday afternoon as the thermal
trough strengthens over the southern Oregon coast. Have issued a
Small Craft Advisory to cover the increased winds and choppy
seas expected through Thursday night. Pressure gradients across
the coastal waters weaken somewhat over the weekend, likely
resulting in a decrease in north to northwest wind speeds.

A persistent northwest swell around 5 to 7 ft is expected to
continue through late week. Seas around 5 to 6 ft today likely
increase to around 7 to 8 ft Thursday through Friday, with a
dominant period of around 8 to 9 seconds. Seas then expected to
subside back to around 5 to 6 ft for the weekend.    /DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from noon to 11 PM PDT Thursday for
     PZZ253.
     Small Craft Advisory from noon Thursday to 5 AM PDT Friday for
     PZZ271>273.
&&

$$

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