908
FXUS66 KMFR 230047
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
547 PM PDT Thu May 22 2025

.UPDATE...Aviation Discussion Updated.


&&

.AVIATION...23/00Z TAFs...VFR conditions continue across northern
California and southern Oregon will persist through the TAF period
except for areas of MVFR ceilings which will develop along the coast
north of Cape Blanco, including at North Bend (KOTH), late this
evening into early Friday morning. Local MVFR is also possible in
the Umpqua Valley late tonight and early Friday morning.


&&

.PREV DISCUSSION... /Issued 202 PM PDT Thu May 22 2025/

DISCUSSION...Generally, westerly flow will continue in the
mid-levels throughout the next week, with periodic waves of
energy passing over the area every other day or so. This low-
impact pattern will keep temperatures near to above normal for
this time of year (with a gradual warming trend as the pattern
gradually becomes more ridge dominated), and also provide a few
periods of shower and thunderstorm chances.

An weak upper trough passed over the area early this morning, and
is now passing to the east. Arriving too early in the day to take
advantage of daytime heating, only a few lingering showers remain
along the northern Cascades, and these should taper off and end
over the next few hours. Shortwave ridging is now building in and
drying the area out, but this will be short lived, as the next
weak upper trough arrives tonight into Friday morning. This
impulse isn`t expected to have much, if any affect on the
weather, other than increased clouds and breezes, and perhaps a
few showers or maybe even a lightning strike or two well east of
the Cascades tomorrow afternoon.

A stronger ridge then builds in for the weekend, with dry
conditions across the region on Saturday and Sunday, and
temperatures rising to levels more typical of late June or early
July.

The next upper trough will slowly move east towards the coast
late Sunday afternoon, and if it gets close enough before the end
of the day, it could trigger a few showers along the coast and an
isolated thunderstorm or two in the northern Cascades. Otherwise,
most shower activity will be along the northern portions of the
forecast area through the overnight and morning hours. By Monday
afternoon, the trough will shift to the east, and shower activity
will intensify along and eats of the Cascades. With the cooler
air aloft, and daytime solar heating in the afternoon, some
modest instability is forecast to develop, so some isolated
thunderstorms are possible, mainly across Klamath and Lake
counties. Any precipitation should dissipate through Monday night
as the trough exits to the east. Temperatures will be a little
cooler Monday, with clouds and showers helping to keep
temperatures right around normal for this time of year.

Models are indicating that ridging will then enter the area and
remain in place through at least Wednesday or Thursday, keeping
the area dry and pushing temperatures back to above normal.
Another trough may be lurking just offshore, however, and could
enter the area late in the week with another round of showers and
cooler temperatures. There is a fairly large spread in the model
guidance regarding the timing and strength of the trough and how
far inland it will push, so changes and updates regarding this
part of the forecast are likely over the next few days. -BPN


MARINE....Updated 200 PM Thursday, May 23, 2025...Below advisory
seas continue today under stable atmospheric conditions. Northerly
winds increase south of Cape Blanco on Friday morning. Wind-built
steep seas are forecast south of Port Orford and within 50 nm of
shore on Friday afternoon through late Friday night.

Below advisory seas return on Saturday. On Sunday, westerly swell
increases through the day, peaking Sunday night into Monday morning.
Scattered marine showers are also possible early Monday morning, but
these should be unimpactful. Stable conditions could return on Monday
afternoon and could continue into the middle of next week. -TAD

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 AM Friday to 5
     AM PDT Saturday for PZZ356-376.

&&

$$