559
FXUS66 KPQR 032127 AAA
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
226 PM PDT Thu Apr 3 2025

.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...Showers have all but ended
throughout the region, and a period of shortwave ridging is expected
for the next few days. Drier and increasingly warm daytime
temperatures through Saturday. High temperatures are around
seasonable today, with afternoon highs in the mid 50s for most
lowland areas. This climbs up to around 70 Friday, and further to the
low/mid 70s Saturday afternoon (the warmest day of the week). Chances
of lowland temperatures breaking 75 degrees on Saturday are under 10%
for most areas, with slightly higher chance at 30% for the Portland
metro due to urban heat island effect. Coastal areas will remain more
mild as they retain a marine layer influence through Saturday.
Afterwards, temperatures drop as we see a pattern change back to
showery seasonable weather on Sunday.

However, in the immediate term, tonight (Thursday night) sees a good
chance for frost formation throughout the region before heating
really picks up. With relatively clear skies and temperatures
dropping to the mid 30s, radiational cooling will be fairly strong
and much of the area will likely see frost concerns tonight as
surface temperatures likely will be several degrees cooler. The
Frost Advisory has been extended to most of the Cascades foothills
as well as the Coast Range Valleys, with much of these areas seeing
temperatures between 33-36 tonight. Portland metro remains out of
the Frost Advisory as temps remain just a hair too warm, closer to
37-39 tonight. /JLiu

.LONG TERM...Sunday through Wednesday...Medium range continues to
show good 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...Widespread VFR across the airspace as high pressure
continues to build over the Pacific Northwest. Which will bring
dry conditions and slowly clearing skies. These conditions 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 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 variable winds less than 10 kt. /42

&&

.MARINE...High pressure will settle over the region through the
remainder of the week. This will bring northerly winds around 5 to
10 kt to all waters. As high pressure moves inland, look for a
more offshore flow pattern to develop on Friday, with winds
becoming southerly ahead of an approaching system by Saturday.
Seas will generally be 3 to 5 ft through Saturday.

The next frontal arrives Saturday evening/Sunday. As the front
approaches, winds and seas will build. Expect Small Craft
Advisory gusts across all waters by Sunday night and they are
expect to increase into Monday. A second, stronger front late
Monday/early Tuesday, will bring a 25% probability for Gale-force
gusts up to 35 kt on Monday. As the front approaches the waters,
seas will build towards 11 to 13 ft on Sunday as a fresh westerly
swell pushes into the waters. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Frost Advisory from midnight tonight to 9 AM PDT Friday for
     ORZ104-105-109-113>118-121-123>125.

WA...Frost Advisory from midnight tonight to 9 AM PDT Friday for
     WAZ205-208.

PZ...None.

&&

$$

www.weather.gov/portland

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