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FXUS66 KPQR 031701 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1001 AM PDT Thu Apr 3 2025

Updated Aviation Discussion

.SYNOPSIS...Mild and dry across the area today with temps near
seasonal normals in the upper 50s. Clearing skies will pave the
way for chilly temps and potential widespread frost formation
tonight into Friday morning. Warm and dry conditions expected
Friday and Saturday with highs in the 70s in the interior
valleys. Cooler and more showery weather returns Sunday into
early next week.

&&

.SHORT TERM...Now through Saturday Night...Radar shows a few
isolated showers lingering across parts of northwest Oregon and
southwest Washington as a weak upper level disturbance departs
the region. Broken mid level cloud cover has helped to keep fog
development at bay as of 3 AM Thursday, with temperatures
generally in the upper 30s to low 40s across the interior
lowlands. Will continue to see remaining shower activity
dissipate through this morning as drier northerly flow takes
hold and makes for a seasonably mild and pleasant day across
the area, with afternoon highs in the upper 50s to around 60
degrees. The primary short term forecast concern remains the
potential for more widespread frost formation tonight as
clearer skies and more efficient radiational cooling allow
temperatures to drop into the mid or even low 30s across much of
the interior lowlands. Opted to issue a Frost Advisory tonight
into Friday for much of the Willamette Valley and the Upper Hood
River Valley as confidence continues to increase for low
temperatures in the 33-36 degree range, with the coldest spots
expected to be in the southern Willamette Valley. Excluded most
of the Portland/Vancouver metro area from the advisory as
temperatures will likely remain in the upper 30s, but the
advisory does cover the Tualatin Valley and outlying areas of
Clark County in WA where temperatures are more likely to dip
into the mid 30s.

Friday and Saturday still look warm and dry with ample sunshine
as high pressure builds over the Pacific Northwest. NBM
probabilistic guidance continues to indicate about a 50/50
chance for temperatures to reach 70 degrees in the Portland area
on Friday, but only around a 20% chance in the rest of the
Willamette Valley. Saturday will be the warmest day of the week
as NBM probs to reach 70 climb above 90% for most of the valley.
Coastal areas will remain more mild as they retain a marine
layer influence through Saturday. /CB

.LONG TERM...Sunday through Wednesday...Medium range guidance
has started to come into better agreement on the arrival of the
next trough on Sunday as the upper level ridge shifts east of
the Cascades. As a result, the forecast has trended cooler and
wetter for Sunday with increasing precipitation chances and NBM
50th percentile temperature guidance residing in the low to mid
60s in the interior lowlands. Expect a benign pattern
characterized by mild temperatures and showery weather to
persist during the first half of next week as ensemble clusters
depict upper level troughing over the NE Pacific and broad onshore
flow across the Pacific Northwest. Models do not indicate any
significant weather impacts across the region within the next
seven days. /CB

&&

.AVIATION...Observations continue to show lingering showers, but
those showers should finally stop within the next few hours.
Lingering showers could result in brief periods of MVFR
conditions through 20Z Thursday. Otherwise, expect widespread VFR
across the airspace. High pressure continues to build over the
Pacific Northwest and this will bring dry conditions along with
clearing skies starting around 20Z Thursday and the clear skies
are expected to persist through the TAF period. Variable winds
less than 10 kt.

Clearing skies, moist ground and near freezing temperatures
overnight could result in some frost development. This is not
expected to be impactful, but exposed surfaces could see some very
light accumulations for locations within the Willamette Valley.
Best time for frost accumulation will be from 07Z through 16Z
Friday.

KAST anemometer is still inoperative. Therefore, TAFs limited to
CIG and VIS.

PDX AND APPROACHES...Predominately VFR conditions through the TAF
period with northwest winds less than 10 kt. /42

&&

.MARINE...High pressure over the northeast Pacific and lower
pressure inland will maintain northerly to northwesterly winds
under 15 kt through the end of the week. Seas will generally be 3
to 5 ft through Saturday. The next front arrives Saturday evening
into Sunday, returning breezy southerly winds across all waters.
As the front approaches, there is a 20-30% probability for Gale-
force southerly wind gusts up to 35 kt on Sunday. As the front
approaches the waters, seas will build towards 11 to 13 ft as a
fresh westerly swell pushes into the waters.

Another strong ebb is expected this (Thursday) morning for the
Columbia River Bar; however, seas with this ebb are forecast
around 4 to 5 ft so minimal impacts expected.   -Alviz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Frost Advisory from midnight tonight to 9 AM PDT Friday for
     ORZ109-113>118-121.

WA...Frost Advisory from midnight tonight to 9 AM PDT Friday for
     WAZ205.

PZ...None.

&&

$$

www.weather.gov/portland

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