043
FXUS66 KPQR 270446 CCB
AFDPQR

Area Forecast Discussion...CORRECTED
National Weather Service Portland OR
945 PM PDT Wed Mar 26 2025

Updated Aviation Discussion

.SYNOPSIS...Thunderstorms and heavy showers through the rest of
the evening. Active weather will continue through the remainder
of the week and into the start of the upcoming week. So, expect
rather typical spring weather with rain showers, Cascade snow
and near normal temperatures.

&&

.SHORT TERM...Now through Thursday Night...Record high
temperatures today with continued chances for thunderstorms.
High clouds were a limiting factor today, but some lingering
instability this evening is triggering thunderstorms throughout
the area. For perspective on how the afternoon has shaped up, at
around 1 PM, a weather balloon was sent which reported CAPE of
around 900 J/kg, while at 5 PM, the balloon reported a CAPE of
only 63 J/kg. The afternoon sounding also shows a few more
capping inversions and a significantly larger one around 850
mph. This environment is a sign that a lot of the instability
was eaten up by earlier convection. With the higher clouds in
place, we were unable to reach temperatures to reach a capping
inversion near the surface, and dew points didn`t reach levels
necessary for significant severe thunderstorms. With all that
said though, the evening is not through and typically we get
some of our peak spring time thunderstorms after 4 PM. Cannot
rule out a severe storm at this point so we continue to monitor,
and a Severe Thunderstorm Watch remains in place through 9 PM.
-Muessle

Previous discussion follows: SPC has around a 15% chance of
hail for most of the Willamette Valley, and furthermore a 10%
chance to see severe hail, or hail with two inches or greater
diameter. Considering EBWD (Effective Shear) values around 55 kt
and a LHP (Large Hail Parameter) around 6.1, there is certainly
potential for significant (>2 inches diameter) hail to be
produced out of thunderstorms this afternoon and evening. It
should be noted that not all thunderstorms will produce
significant hail, but there is the potential for any
thunderstorm to do so.

With regards to wind, DCAPE values around 1000 J/kg are forecast,
along with steep low level lapse rates and PWAT values over 1 inch.
As such, conditions are favorable for strong downdraft winds up to
potentially 60-70 mph localized around thunderstorms.

SPC also has a 5% chance of tornados throughout the Willamette Valley
and SW Washington lowlands, including along the I-5 corridor this
afternoon and evening. With strong CAPE values 2500-3500 J/kg, as
well as effective SRH around 150 m2/s2 and bulk wind difference
around 50-60 kt, conditions are somewhat favorable for enough
rotation to induce mesocyclonic tornado formation. Effective SigTor
(significant tornado parameter) values are around 0.5-1.0, further
indicating the possibility of tornados. While conditions are more
favorable for tornado formation than other thunderstorm systems in
recent memory, SPC risk is still only 5%, meaning this is still a
fairly unlikely occurrence.

In summary, the highest threat is likely for hail, with the largest
hail expected to have a diameter around 1.75-2 inches. Damaging winds
up to 60-70 mph will be possible (localized around thunderstorms),
along with a 5% chance of tornados. Brief but heavy rain will of
course also be possible around any thunderstorms. Proper precautions
should be taken, and people should remain inside while thunderstorms
are directly impacting their area. To prepare for damaging winds,
cars should not be parked under trees in case of tree damage,
preferably parking in a garage if available (as severe hail can
damage vehicles left outside). Make sure you have a way to receive
NWS weather alerts; if a Severe Thunderstorm or Tornado Warning is
issued, make sure to stay indoors and away from windows.

Thursday, will maintain cooler weather and while the very
favorable south/southwest flow pattern will persist, current
conditions are looking to be less favorable for thunderstorm
development. Model soundings show CAPE values plummeting towards
100-250 J/kg along with 15 J/kg of CIN. This means that the
overall environmental conditions within the atmosphere are not
as favorable for thunderstorm development. Still, will continue
to monitor as this could change. Possibility of strong winds has
decreased for Thursday, with only a 10-25% probability for southerly
gusts up to 45 mph for the Willamette Valley with the highest
probability around Salem. The coast has a 10-30% probability for
southerly gusts up to 55 mph. Note these probabilities have decreased
over the past 12-24 hours. We will continue to monitor the
forecast. -JLiu /42

.LONG TERM...Friday through Tuesday...Minimal change in the
forecast for the latter part of the week and into the start of
next week. Expect a generally active pattern with temperatures
showing a cooling trend back towards seasonal normals. This
means daytime highs in the 50s to low 60s. Training systems
will also result in additional rounds of rain showers and
Cascade snow. -42

&&

.AVIATION...Radar and satellite show some lingering showers around
the area with a few isolated lightning strikes. The bulk of the
thunderstorms have passed, with heavier showers still persisting
around KUAO, and other surrounding runways. Within showers, outflow
winds up to 30 kt possible, with heavy rain and small hail. The
strong low pressure system that brought the active weather is
pushing inland which will cause winds to shift to the south and
increase after 17Z Thursday. Areas along the coast, and along
north/south aligned terrain like the Willamette Valley, will
experience the strongest winds. Gusts up to 35 kt possible in some
locations, especially approaches into KNOP, KAST, and KEUG. At 2500
ft and above, winds are south to southwesterly up to 45 kt. Will
continue to watch for any signs of LLWS.

PDX AND APPROACHES...Scattered lingering showers with gusty outflow
winds. Chances for thunderstorms less than 5%. Winds will become
southerly and gusty in the later half of the TAF as the low moves
in. Strong south winds, especially above 1000 ft with speeds up to
35 kt. At the surface, gusts will be closer to 25 kt. LLWS not
expected but given the runway orientation, cannot exclude some level
of crosswinds.                                          -Muessle

&&

.MARINE...Wednesday into Thursday, there remains high confidence
that a strong area of low pressure will bring much higher winds
and seas across the waters. Storm-force winds are likely to occur
with this system with wind gusts up to 50 kt expected in the
outer waters south of Cape Falcon. Elsewhere north of Cape Falcon
and across the inner waters including the Columbia River Bar,
gale-force gusts up to 40-45 kt are likely. Seas will also
rapidly increase, becoming steep and hazardous Wednesday night
into Thursday with significant wave heights most likely peaking
between 20-25 feet. Storm and Gale Warnings remain in effect across
the waters from Wednesday afternoon through Thursday night
following a period of small craft advisory conditions Wednesday
morning through Wednesday evening. Note the start time for gale
to storm-force winds now looks to start later than initially
expected, beginning Wednesday night for the central/southern
waters and Thursday morning for the northern waters and Columbia
River Bar.

Hazardous seas over 15 ft will likely persist through Friday
afternoon, however winds and seas look to fall significantly late
Saturday into Sunday. -TK/Picard

&&

.BEACH HAZARDS...Beachgoers and those participating in the
upcoming razor clam digs should be aware of a moderate risk of
sneaker waves most of this week. Be sure to never turn your back
to the ocean and keep a close eye on incoming waves, as sneaker
waves can catch beachgoers by surprise, sometimes resulting in
injury or death. Avoid jetties, large logs, and large rocks.
Elevated surf conditions are expected Thursday into Friday with
wave heights potentially exceeding 25 ft, however much of the
surf energy will be directed along-shore given the southwesterly
swell direction. This will limit surf impacts to area beaches.
Forecast surf energy is currently below criteria for the issuance
of a high surf advisory.

Lastly, there is a chance of marginal tidal overflow flooding
along the south WA coast around high tide early Friday morning. As
of right now, the total tide forecast at Toke Point, WA is
forecast to reach 11.0 feet for one hour. Typically, flooding impacts
do not occur unless the total tide exceeds 11 feet for a few
hours. Therefore have decided not to issue a coastal flood advisory,
but this could change if the total tide forecast increases with
future forecast updates. -TK

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 11 AM PDT Thursday for PZZ210.
     Gale Warning from 11 AM Thursday to 5 AM PDT Friday for PZZ210.
     Small Craft Advisory until 5 AM PDT Thursday for PZZ251-271.
     Gale Warning from 5 AM Thursday to 5 AM PDT Friday for PZZ251-
     271.
     Small Craft Advisory until 2 AM PDT Thursday for PZZ252-253.
     Gale Warning from 2 AM Thursday to 5 AM PDT Friday for PZZ252-
     253.
     Small Craft Advisory until 11 PM PDT this evening for PZZ272-
     273.
     Gale Warning from 11 PM this evening to 8 AM PDT Thursday for
     PZZ272-273.
     Storm Warning from 8 AM to 5 PM PDT Thursday for PZZ272-273.
&&

$$

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