656
FXUS66 KPQR 052308
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
408 PM PDT Sat Oct 5 2024

.SYNOPSIS...
High pressure will result in areas of late night and morning
valley fog with mostly sunny afternoons and pleasant
temperatures for the next several days. A series of weakening
fronts will bring increasing chance for light rain later this
work week.

&&

.DISCUSSION...

KEY MESSAGES:

 - Areas of late night and morning valley fog followed by warm
   days through Monday.

 - A series of weak fronts approaching the region will bring
   increasing chances for light rain this week. The increase in
   onshore flow will produce cooling temperatures Tuesday
   through Friday.

 - >80% of the ensembles indicate a return to shortwave ridging
   and warming temperatures over the Pacific Northwest next
   weekend.

WEATHER PATTERN OVERVIEW:

Shortwave ridging over the Pacific Northwest will bring plenty
of sunshine, above average high temperatures, cool nights and
some areas of valley fog late at night and each morning through
at least Monday. Given warming temperatures, frost should be
less of an issue the next few nights even in our typically
coldest locations so no frost/freeze highlights are anticipated
in the short term.

A shortwave trough over the Gulf of Alaska will gradually shift
closer to the Pacific Northwest Monday into Tuesday, which will
initiate a cooling trend across the region. A weak front and
attendant band of light rain will slide southeastward towards
the region on Tuesday, but there is a lot of uncertainty in how
far southeastward in the forecast area the front and band of
light rain will make it, but it appears unlikely (<10% chance) to
reach the fires still smoldering/burning in eastern Lane
County. Additional fronts appear more likely than not to push
towards the region late in the week, but timing uncertainty in
when rain will arrive is still only producing a 30-50% of rain
in any given 6-hour time period across the region Friday. It
should be noted that the NBM`s highest probabilities (~10-30%) for
temperatures capable of producing frost in our colder locations
like the Upper Hood River Valley, Battle Ground, Vernonia,
Hillsboro and Colton are Thursday and Friday nights.

More ensemble members from the EPS, GEFS and GEPS come around
to the idea of shortwave ridging building across the Pacific
Northwest next weekend with more than 80% of the members
producing mild temperatures and dry weather across the region
next weekend.

FORECAST CONFIDENCE AND DEVIATIONS...Made few deviations from
the NBM in the official forecast given it appears to fall in
the middle of the ensemble space with regards to temperatures,
precipitation chances, etc..



&&


.AVIATION...Fog and low stratus have cleared from the area as high
pressure builds into the area. VFR conditions are expected into
the evening with clear skies and light north winds at 5 to 10
knots. Clear skies this evening and weakening winds should set
the stage for additional fog and low clouds to develop for several
inland taf sites. TAF guidance suggests IFR or lower conditions
developing between 6-12Z for most locations and lasting until
15-18Z. However, HREF probabilities suggest little to no
fog/stratus formation tonight and digging deeper into the higher
res models, little to no sub-VFR conditions. Deterministic NBM
does suggests fog developing from KUAO south to KEUG. If fog does
develop, it will likely dissipate faster than today given
conditions have remained dry today.

PDX APPROACHES...VFR conditions expected through this evening. Light
winds and clear skies will lead to possible fog development but
probabilities continue to decrease with a 10-15% chance between
10-15Z Sunday. -Batz

&&

.MARINE...Benign conditions expected as high pressure over the
region will stay in place for next several days, with thermal low
pressure along the south Oregon coast. As such, will see northerly
winds on the coastal waters, generally at 10 to 15 kt. Even with
that, the strongest winds will stay south of the Newport. Seas 4
to 5 feet will increase to around 6 to 7 feet on Monday as a
system moves well to our north. Seas subside a foot or two into
the latter part of next week. -Batz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.


&&

$$

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