472
FXUS66 KPQR 192102
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
125 PM PDT Thu Sep 19 2024


.SYNOPSIS...High pressure will maintain dry weather with temperatures
more typical of late September through the start of next week. A weak
front will bring a chance of showers Sunday into Monday for northern
parts of the forecast area, with a slightly stronger front during the
middle of next week. Warm, dry weather likely to return for the
latter part of next week.

&&

.SHORT TERM...Tonight through Saturday night...High pressure will
continue to be the dominant synoptic feature over the Pacific NW
through the weekend. This will maintain variable onshore flow and
result in clouds returning overnight and scouring out each
afternoon/evening. Overall, expect a slight warming trend though the
latter part of this week and into the weekend as the aforementioned
upper level high slowly drifts inland. This scenario will also result
in the development of a thermally induced trough. Which looks to set
up along the southern Oregon coast and slowly stretch northward
through Saturday. This will also aid in maintaining northwesterly
flow, which will result in breezy west/northwest winds for Friday,
especially over the higher terrain and through the middle and
eastern end of the Columbia Gorge. For the start of the weekend
expect less wind, less clouds and tad warmer conditions. Daytime
highs will generally be around seasonal norms or just a touch
higher. So, expect daytime highs through Saturday to be in the mid
to upper 70s across the inland portions of the forecast area and
temperatures along the coast running about 10 degrees cooler IE the
mid to upper 60s. /42

.LONG TERM...Sunday through Thursday...Sunday looks to feature a
fairly zonal upper level flow regime across the Pacific Northwest,
maintaining dry and seasonable weather with inland high temperatures
in the mid to upper 70s. A weak upper level disturbance skirting the
Canadian border will bring a slight chance of rain across southwest
Washington and far northwest Oregon Sunday evening into Sunday night,
but expect most locations to ultimately remain dry. Medium range
guidance continues to converge on a warmer and drier solution for the
start of next week, with ensemble clusters and 12z deterministic
models both showing good agreement on an upper level ridge building
over the Pacific Northwest on Monday and shifting inland on Tuesday.
This will bring well above normal temperatures to the area on Tuesday
as highs climb into the mid to perhaps upper 80s in the interior
valleys. The potential for temperatures higher than that appears
rather minimal as latest probabilistic guidance gives only about a
10 percent chance to reach 90 degrees in the Portland area and closer
to a 30 percent chance from Salem to Eugene. Any heat concerns look
to be limited to just Tuesday as the ridge shifts east of the region
and temperatures trend back down mid to late week. Guidance also
depicts a short lived period of offshore flow developing late Monday
into early Tuesday. Not overly concerned about east winds at this
time given the progressive nature of the pattern and fairly modest
offshore pressure gradients, but will be something worth keeping an
eye on for those in the fire weather community as roughly half of
European ensemble members depict wind gusts reaching 25 mph in the
vicinity of the Columbia River Gorge late Monday into early Tuesday.
Still some uncertainty beyond Tuesday as the ridge shifts east to the
Rockies, with guidance remaining split on the strength and timing of
an upper level trough arriving Wednesday into Thursday. NBM mean
solution depicts temperatures moderating to near seasonal norms with
chance to slight chance PoPs returning to coastal and northern parts
of the area during the middle of the week. /CB

&&

.AVIATION...Upper level ridge with dry northwest flow aloft
persists through Thursday night. Expect mostly sunny skies with
variable high clouds through this evening, with some lingering
coastal stratus as lower level flow remains onshore. Will likely
see a similar repeat of stratus redevelopment by 02z at the coast
(60-80%) and after 12z inland (40-70%), especially across northern
parts of the forecast area. Generally expect north to northwest
winds, increasing during the afternoon.

PDX APPROACHES...VFR expected with variable high clouds through
this evening. There is around a 50% chance of MVFR redevelopment
after 12z Friday. Expect northwest winds to around 6-8 kt Thursday
afternoon. /DH

&&

.MARINE...Not much change as high pressure persists over the
coastal waters, resulting in a summer like pattern of northerly
winds today through Friday. As the thermal trough strengthens over
the southern Oregon coast, winds will likely gust up to 20-25 kt
over the outer coastal waters this afternoon through tonight. Also
expect winds to gust up to 25 kt across the inner coastal waters
south of Cape Foulweather through this evening. The Small Craft
Advisory continues to cover the increased winds and choppy seas
expected through tonight. 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 will maintain seas around 6 to 8 ft
through Friday, with a dominant period of around 8 to 10 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 4 PM this afternoon to 8 PM PDT this
     evening for PZZ210.

     Small Craft Advisory until 11 PM PDT this evening for PZZ253.

     Small Craft Advisory until 5 AM PDT Friday for PZZ271>273.
&&

$$

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