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196
FXUS66 KMFR 051152
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
452 AM PDT Wed Jun 5 2024

...Updated AVIATION Discussion...

.DISCUSSION...A surge of stratus from the coast into the Umpqua
Valley will erode this morning. The strong warming trend will
continue into Friday, but conditions will remain much warmer and
drier than normal through early next week. This includes a Chetco
Effect of downslope warming for Brookings with relatively light
northeast low level flow today, becoming strongest with a high
around 80 Thursday, then lingering into Friday morning.

The focus for the forecast issuance was upon fine tuning the
probability of convection. Slight chances of late day
thunderstorms will be present in portions of the area today
through at least Sunday. The highest probability will be in
southern and eastern Modoc County today, Modoc and southern Lake
counties Thursday, and northern portions of Klamath and Lake
counties (secondarily from central Siskiyou into the remainder of
Klamath county) Friday. The thunderstorm probability begins
modestly today, in northern California with increasing moisture
aloft, associated with a shortwave, extending northeastward into
Modoc County. A similar scenario, but a slightly stronger
shortwave is anticipated to bring a slight chance to a broader
swath of northern California and the east side on Thursday. Model
differences arise Friday with the ECMWF indicating ridging, but
the GFS continuing a variation of the ongoing pattern with another
shortwave in the southwest flow aloft.

Model differences increase going into the weekend with a broad
trough in the Gulf of Alaska expected to approach the west coast.
There are contingents of solutions that are slower or faster
bringing a trough inland, as well as differences in the strength
and position of troughing, and (though not the favored solution) the
possibility of a piece of energy breaking off and developing into
a closed low along the coast (which would increase thunderstorm
probabilities in our area around Sunday and/or Monday).

During many years, in early June, we will see a gradual transition
into summer with a weakening storm track shifting north of our
area. The pattern for the next couple of weeks looks to be
relatively complex with a stronger than normal areas of low
pressure frequently anchored in the Gulf of Alaska. With that
currently the case, there is a hazardous episode of higher than
normal surf on-going through this evening. Please see the beach
hazards section below. -DW

&&

.AVIATION...
-- Changed Discussion --
05/12Z TAFs...Marine stratus remains over most of the
Oregon coast and into the Umpqua Valley this morning, bringing
generally MVFR ceilings and occasional lower visibilities. Periods
of IFR levels have been observed, but have not persisted. Guidance
is split on whether marine stratus will clear out or continue, with
more confidence in a clear period before stratus rebuilds along the
coast towards the end of the TAF period. Gusty northerly winds will
blow along the coast this afternoon before calming in the evening.

Other inland areas will remain at VFR levels under clear skies.

-TAD
-- End Changed Discussion --

&&

.MARINE...Updated 200 AM Wednesday, June 5, 2024...Long-period
westerly swell will build in all waters this morning, sustaining
continued steep seas. Swell of 11 to 13 feet at 14 to 15 seconds
will develop through this morning, then start to steadily decrease.
Combined seas are expected to have unseasonably high surf of 15 to
18 feet through Thursday morning.

As the long-period swell starts to decrease this afternoon, a
thermal trough will start to develop and bring gusty northerly winds
across most area waters. The strongest winds will be south of Cape
Blanco and within 40 nm from shore. Steep seas will continue in
waters north of Cape Blanco, while very steep and hazardous wind-
built seas will develop south of Cape Blanco this evening.
Currently, these conditions are expected to continue through at
least Friday morning. Winds are forecast to peak on Thursday
evening, with gale gusts possible south of Gold Beach.

Please see MWWMFR for more detail about Small Craft Advisories and
Hazardous Seas Warnings in place through Friday morning.

Seas start to calm on Friday, although some amount of steep seas
will continue through the morning. Active seas are expected to
return on Saturday evening as a thermal trough rebuilds over area
waters and remains into next week. -TAD

&&

.BEACH HAZARDS...Updated 230 AM Wednesday, June 5, 2024...Abnormally
high waves and surf are expected through this evening due to a
late season west swell of 10 to 13 ft at 14 to 15 seconds. This
will result in surf heights of 16 to 19 ft, which is uncommon for
June. These higher than usual conditions could catch beach goers
off guard, especially those not familiar with the Pacific Ocean.
If people are caught off guard, they could be knocked off their
feet and pulled into the cold ocean waters, resulting in
hypothermia or worse. If you see someone get swept into the ocean,
do not go after them. Instead call 911 immediately and keep an
eye on them until help arrives. Avoid climbing on rocks and
jetties. Keep your distance from the ocean and remain out of the
surf zone to avoid hazardous conditions. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement through this evening for ORZ021-022.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Friday
     for PZZ350-356-370-376.

     Hazardous Seas Warning from 5 PM this afternoon to 5 AM PDT
     Friday for PZZ356-376.

&&

$$