854
FXUS66 KPQR 251056
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
356 AM PDT Tue Jun 25 2024

.SYNOPSIS...Another day of warm, dry conditions is expected as a
weak ridge overhead shifts eastward through the day. An upper
level trough will then bring relatively cooler temperatures for
Wednesday and Thursday with increasing chances for rain showers.
Rainfall totals aren`t expected to be significant across most of
the area. Warm and dry conditions will return Friday and
Saturday with near normal to slightly above normal temperatures.

&&

.SHORT TERM...Now through Thursday Night...Another warm day is
in store today before a cooldown comes Wednesday and Thursday.
Shortwave ridging remains in palace across the PNW while a
large upper level trough is located across the northeast
Pacific. The transient ridge will keep skies clear and will
support temperatures 5-10 degrees warmer than yesterday through
the Willamette Valley with highs peaking in the mid 80s to
around 90 in a few spots. NBM probabilities show a 50-80% for
temps to reach at least 85 and a 20-50% chance of reaching 90 or
higher. The coast will remain cooler with temps peaking in the
mid to upper 60s.

Riding moves eastward through the day while the trough off the coast
amplifies and shifts southwest flow more southerly. A surface low
supported by the trough will move eastward, lifting a weak warm
front through the region Wednesday afternoon, introducing a slight
chance (10-30%) for showers, mainly across the Coast Range from
Lincoln City northward and the Cascades in Washington. A better
chance for showers will come Wednesday evening into the overnight
hours as a weak cold front comes onshore and passes through the
area. PoPs peak late Wednesday into Thursday morning, 30-70% north
or Salem and 10-30% south of Salem. Given the weak nature of
the front and limited moisture, QPF totals are not expected to
amount to anything decent for much of the area. NBM guidance
suggests a wide range for 0.1" across the area, the Coast Range
north of Lincoln City sits at a 40-60% chance, 20-30% north of
Salem and less than 10% south of Salem. The Best chance will be
across the Washington Cascades at 60-80%. Much cooler temps are
expected on Wednesday, peaking in the low to mid 70s in the
Willamette Valley and in the upper 50s to low 60s along the
Coast. Thursday will be a few degrees cooler across much of the
area. -Batz

.LONG TERM...Friday through Monday...The trough will exit the region
late Thursday and will bring an end to any remaining showers.
Cluster analysis shows good agreement in weak ridging or zonal
flow developing in the wake of the trough which will help
support warming temps to end the work week. Highs for the
Willamette Valley should rise back into the upper 70s to low 80s
Friday and Saturday as NBM guidance indicates a 40-60% chance
of temps reaching or surpassing 80 both days. Another weak short
wave crossing the Gulf of Alaska begins to shift southward
along the west coast which could bring another round of light
showers Saturday night. -Batz

&&

.AVIATION...High pressure remains over the region, with dry mild
southwest flow aloft. VFR expected through the forecast period.
However at the coast spotty MVFR to IFR cigs may form (10-30%
chance) 12Z-16Z Tue. For tonight upper trough approaching will
increase southwest flow inducing stronger onshore flow at the low
levels. This will likely bring stratus to the coast later tonight
with probabilities increasing to 60-80% after 09Z Wed.

Winds generally northerly less than 10 kt today, but 10 to 15 kt
at the coast this afternoon. Winds back to southwest tonight.

PDX AND APPROACHES...High pressure with mild dry southwest flow
aloft will maintain VFR under clear skies.

&&

.MARINE...High anchored off the Pac NW weakens today as a
weakening trough moves through the waters tonight into Wednesday.
As a result will see a wind reversal late tonight into Wednesday
from northerly to southwesterly. Winds expected to remain below 20
kt.

Seas remain in the to 4 to 6 ft range through most of the week
as a westerly swell moves across the waters.

&&

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

$$

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