National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KPQR 152054
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
153 PM PDT Mon Apr 15 2024

.SYNOPSIS...Onshore flow will maintain plenty of clouds and cooler
temperatures across the region through Tuesday, along with a few
showers. High pressure builds across region for Wednesday to Friday,
with return of dry weather and warming temperatures. Bit more
unsettled for next weekend, with more clouds and perhaps even some
showers.

&&

.SHORT TERM...Monday afternoon through Wednesday...Radar imagery
shows showers across NW Oregon and SW Washington this afternoon,
mainly north of Salem and over the Cascades as a weakening upper
trough continues slowly pushing into the region today, though main
core of the system remains well to the north over north Washington
into southern British Columbia. The system offshore is not all that
strong with rather zonal flow aloft off the Pacific into the Pacific
NW today into tonight. Rainfall amounts will be very meager with up
to 0.1 to 0.2 inch over the south Washington Cascades into the far
north Oregon Cascades. Likely to see only a trace to perhaps up to
0.05 inch for inland lowlands. Onshore flow will maintain plenty of
clouds today, with some gaps in the clouds from time to time.
Temperatures will be cooler today with highs in the mid to upper 50s
in the lowlands, slightly below mid-April normals.

Overall, not a lot of change for the region for Tuesday, as will
maintain moderate onshore flow with mostly zonal upper level flow.
The shower potential will be more limited to SW Washington as well
as the higher terrain north of Tillamook to Portland to Mt Hood
line. Surface ridge axis will be shifting northward slowly during
the afternoon. As such, would expect to see clouds breaking apart,
mainly over western Oregon. Would not be surprised if Salem
southward through the Eugene/Springfield area becoming partly to
mostly sunny in the afternoon.

High pressure offshore continues to strengthen on Tuesday night into
Wednesday. Air mass will be drier Tuesday night, and with clearing
skies and light winds, temperatures will drop into the lower to
middle 30s over most of the region away from the immediate coast.
Most locations are likely to see frost Tuesday night into Wednesday
morning. Otherwise, after a chilly start, should end up with rather
pleasant Wednesday, with sunny skies and a warming trend beginning
with temperatures 55 to 60 along the coast and 60 to 65 for most of
the interior lowlands east of the Coast Range/Willapa Hills. -
Rockey/HEC

.LONG TERM...(THURSDAY THROUGH SUNDAY)...WPC 500 mb cluster
analysis indicates that ensembles are in agreement that upper level
ridging will continue building over the eastern Pacific and shift
east to just off the West Coast Thursday into Friday. At the
surface, high pressure strengthens off the coast with a thermal
trough building north from California into western Oregon. Due to
this, sunny skies and a warming trend will continue across NW Oregon
and SW Washington. Inland valley temperatures will inch towards the
70s once again with NBM indicating 55-75% of temperatures exceeding
70 degrees on Thursday and a 70-85% probably of the same on Friday.
This pattern will also result in increased surface pressure
gradients over the Cascades and Columbia River Valley, producing
increased offshore (easterly) winds for areas near the Columbia
River and Cascades, strongest through the Columbia River Gorge. NBM
indicates roughly 50-70% probability of wind gusts exceeding 30 mph
Thursday and Friday for the Cascades and locations north of Salem.
Additionally, NBM indicates a 60-80% probability for wind gusts to
exceed 45 mph for the Columbia River Gorge Friday.

Beyond Friday, ensembles are still uncertain at the exact pattern.
About 30% of the 500 mb clusters indicate ridging will continue
through the weekend, which would allow for warm and dry conditions
to continue. About 50% of the clusters indicate ridging will begin
to weaken or even become more zonal flow, which would allow
temperatures to cool somewhat, potentially back to seasonal normals
(low 60s for inland locations, upper 50s for the coast). The other
20% or so of the clusters indicate weak troughing will impact the
region, bringing near to below normal temperatures and light
showers. No matter which solution winds up occurring, no impactful
weather is expected in the extended period. -HEC

&&

.AVIATION...Predominately VFR with widespread mid and high level
clouds through the remainder of the TAF period. Northwest winds
for all locations with gusts up to 20 kt along the coast through
at least 00Z Wednesday before decreasing afterwards.

PDX AND APPROACHES...Predominately VFR conditions. Northwest
winds around 5-10 kt through the period, strongest during
afternoon and evening hours. /42

&&

.MARINE... Late tonight through early Tuesday the region gets
brushed by an upper-level trough dropping into northeast
Washington. Midweek and continuing into the weekend, guidance
continues to show a ridging pattern developing which would likely
lead to continued N/NE surface flow. Friday and continuing into
the weekend with seas around 4 to 6 feet at 13 to 15 seconds. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&

$$


www.weather.gov/portland

Interact with us via social media:
www.facebook.com/NWSPortland
www.twitter.com/NWSPortland