-- Discussion containing changed information from previous version are highlighted. --
223
FXUS66 KMFR 201907
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1207 PM PDT Thu Jun 20 2024

.UPDATE...
-- Changed Discussion --
Updated aviation section for 18z TAFs.

.AVIATION...19/18Z TAFs...IFR ceilings are slowly receding to the
coast and should clear within the next 2 to 3 hours as strong
north winds develop this afternoon. The IFR/LIFR ceilings & Vis
will become extensive again early this evening then persist into
Friday morning.

Inland, VFR ceilings will persist through the TAF period, with
cirrus moving off to the east, leaving a truly blue ski day. There
could be some high level smoke (6kft or higher) moving in from fires
burning in California during the evening, but we are not
expecting much if any to become trapped at the surface.
-Miles
-- End Changed Discussion --

&&

UPDATE...Satellite imagery is showing a large cirrus shield
moving across the area at this time. These should thin out from
west to east across the area later this morning and this
afternoon. Forecast high temperatures look good with highs in the
upper 80s/low 90s inland west of the Cascades and mostly in the
80s over the east side. Coastal stratus is thick this morning with
a few sites reporting drizzle earlier. These clouds will peel
back toward the beaches this afternoon/evening, but may not go
away completely. Clouds and patchy drizzle will return to those
areas tonight. Inland areas will continue to warm up through
Saturday with the warmest weather Friday/Saturday. -Spilde

PREV DISCUSSION... /Issued 329 AM PDT Thu Jun 20 2024/

DISCUSSION...Today will be another day of warm weather across
northern California and southern Oregon, with temperatures slightly
higher than Wednesday`s across this area. The Oregon coast will see
highs in the high 60s to mid 70s and west side valleys will be in
the high 80s to low 90s. Areas east of the Cascades will generally
be in the mid 80s. A band of upper level instability is helping to
develop some mid- and high-level cloud cover this morning, but
skies will be mostly clear by late this afternoon. Some very
slight 3-6% thunderstorm chances remain in the forecast over the
Cascades and western Siskiyou County this evening. The moisture
and uplift for widespread activity is not expected, but a few
isolated thunderstorms aren`t impossible. These chances disappear
quickly into tonight.

A gradual warming trend will continue through Friday and Saturday
afternoons across the area. West side valleys will be in the low to
mid 90s, with a 50% possibility for some triple digits in parts of
western Siskiyou County on Saturday afternoon. Areas to the east
will be in the mid to high 80s on Friday and warm further to the low
90s on Saturday. Areas of Level 2 "Moderate" heat risk already
present in west side valleys will spread to the east on Friday and
Saturday. Nighttime cooling is sufficient to stay out of warning
product thresholds, but individuals who are sensitive to heat will
want to carefully consider their daytime activities. Additionally,
staying properly hydrated and minimizing activity during the hottest
parts of the day are good ways for anyone to avoid negative effects
of these unseasonable daytime highs.

A low pressure system will settle near the Canadian coast on Sunday
and bring an upper trough over the area. A weak front will push
marine moisture over Coos and western Douglas County on Sunday
morning, possibly bringing some drizzly showers but will otherwise
be unimpactful. Temperatures across the area will cool slightly but
remain about 5 degrees above seasonal norms into next week.
Afternoon wind gusts will be slightly stronger over Jackson and
Siskiyou counties as well as east side areas through at least
midweek as an upper trough remains in place, but these gusts are not
expected to approach Advisory levels. -TAD

AVIATION 19/12Z TAFs...LIFR ceilings have built into the coast
with patchy LIFR visibilities in fog. These lower ceilings are
expected to persist through mid-morning, around 18Z, and patches are
likely to persist through the afternoon hours. The LIFR will become
extensive again early this evening then persist into Friday morning.

Inland, VFR ceilings will persist through the TAF period, with a
band of high level cirrus that will be thickest during the morning.
-DW

MARINE...Updated 230 AM Thursday, June 20, 2024...High pressure
offshore and a thermal trough along/near the coast will remain in
place through Monday. This will result in persistent northerly winds
and areas of steep to very steep wind-driven seas. Winds will be
strongest south of Cape Blanco and trend higher through Friday. Very
steep seas and occasional gusts to gale force are likely south of
Pistol River out to 30 nm from shore from Friday afternoon into
Friday night.

Slight improvement is expected Saturday into Saturday night as a
front brings a surge of stratus with light showers possible.

-Sargeant/DW

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 AM PDT Saturday
     for PZZ356-370-376.

Hazardous Seas Watch from Friday afternoon through late Friday
     night for PZZ356-376.

&&

$$