McCloud, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

856
FXUS66 KMFR 210335
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
835 PM PDT Sun Apr 20 2025

.DISCUSSION...Updated Marine section...

&&

.MARINE...Updated 830 PM Sunday, April 20th...A thermal trough
will remain in place through most of the week, bringing gusty
northerly winds. Very steep and hazardous seas continue south of
Gold Beach through Monday morning, and steep seas continue between
Gold Beach and Cape Blanco.

On Monday afternoon, the thermal trough will strengthen. Gale gusts
will be possible south of Gold Beach and within 40 nm from the
shore. Very steep and hazardous seas are expected for waters south
of Ophir not covered by a Gale Warning, with steep seas building in
all other area waters. These conditions continue through Tuesday
night.

The thermal trough weakens through Wednesday and Thursday, with
steady improvement in sea conditions. Below advisory conditions may
be possible for all waters by Thursday afternoon. Unsettled seas
could return on Friday ahead of active weather. -TAD/Hermansen

&&

.PREV DISCUSSION... /Issued 435 PM PDT Sun Apr 20 2025/

DISCUSSION...Updated Aviation Section...

AVIATION...21/00Z TAFs...Low VFR ceilings are found in the Umpqua
Basin this afternoon with some scattered to broken MVFR ceilings at
the coast near Coos Bay.

Other areas look to remain at VFR levels through the TAF period,
with only diurnal wind changes to address in the forecast. Northerly
winds will gust again tomorrow afternoon for the coast and Umpqua
Basin, with the stronger winds reaching the Rogue Valley
(Medford) later in the afternoon. -TAD/Hermansen

PREV DISCUSSION... /Issued 241 PM PDT Sun Apr 20 2025/

DISCUSSION...Aside from some marine layer clouds in the Umpqua
Basin and some patchy cumulus fields along and east of the
Cascades, area skies are clear. A weak and barely discernible
front, more akin to a marine layer surge, is passing through
today, producing breezy winds across the area. Otherwise, it is
another quiet, mild spring day, perfect for outdoor activity.

A few models, namely the deterministic GFS and a few of the hi-res
convection allowing models, are showing a narrow band of
showers developing along a weak convergence zone lying right along
the far southern portions of Modoc and far southeastern portions
of Siskiyou counties this afternoon. Instability is week, but with
convergence at the surface and a weak shortwave aloft, a few
showers or perhaps a roll of thunder or two are not out of the
realm of possibility. The forecast reflects this possibility, but
most likely nothing more than some cumulus fields and virga will
occur. Otherwise, today, Monday, and Tuesday will be quiet, with
mostly clear skies, cool mornings and mild afternoons.

Another weak trough is forecast to cross the region Tuesday night
into Wednesday. The vast majority of ensemble members depict
another dry frontal passage, but a few (mainly within the EC and
NAM suites) are showing an area of convection developing over
northern California Tuesday night into early Wednesday, then
spreading north and east through the morning before dissipating in
the afternoon. A quick look at model soundings suggest that this
would be high based convection with relatively shallow CAPE, but
the instability is there, and with the trough passing overhead,
the lifting is there as well. Moisture, however, is very limited,
with PW values of around 0.30 inches, and this will be the
deciding factor. Have added some shower/thunder wording to the
forecast during this time, but a safe bet would again be for no
significant convective development at all. If any showers do make
an appearance, they are likely to be dry. The remainder of the
area will remain dry through Wednesday.

A pattern change then arrives Thursday, introducing a period of
cooler and wetter weather for the weekend. A much more robust
trough will pass by the Aleutians and dig to the southeast,
approaching the coast of the Pacific Northwest by Thursday
afternoon before passing overhead Friday, then followed by a few
more shortwaves/troughs through the weekend. Guidance agrees on
this basic premise, but differs by a great deal regarding the
speed and track of the individual features. The most likely
scenario would be for a mostly dry Thursday morning, followed by
convective development in the afternoon and evening as the trough
edges closer and taps into some southerly moisture and afternoon
heating, essentially resulting in scattered showers and perhaps a
few thunderstorms. Shower chances then overspread the area Friday
through Sunday as the initial trough and the following impulses
pass overhead. The timing of highest shower chances will have to
wait until the models come to better agreement on the individual
features, but for now, the best chances for precipitation appear
to be in the afternoons, when peak daytime heating and the
resulting instability coincide with passing vorticity maximums.
-BPN

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Tuesday
     for PZZ356-376.

Small Craft Advisory from 11 AM Monday to 11 PM PDT Tuesday for
     PZZ350-370.

     Hazardous Seas Warning until 11 PM PDT Tuesday for PZZ356-376.

     Gale Warning from 11 AM Monday to 11 PM PDT Tuesday for PZZ356-
     376.

&&

$$