880
FXUS66 KMFR 101122
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
422 AM PDT Tue Sep 10 2024

.DISCUSSION...It will be a bit cooler today, most noticeably west
of the Cascades, with another afternoon and evening of breezy
winds.

A cold, wet upper trough off the southern Alaskan
coast will continue to track southeast, moving across Oregon on
Wednesday. It`s emblematic of the substantial change in our
weather that even though today, and Friday into Saturday look to
have the highest probability of being dry days inland, there will
be patchy morning coastal drizzle both today and Saturday.
Otherwise, the pattern will be active with the highest probability
for measureable rain late tonight through Wednesday night, and
then next week around Sunday and around Tuesday into Tuesday
night.

This includes a slight chance to chance of thunderstorms late
tonight into Wednesday evening. The highest probability will be
in Oregon in the vicinity of center of the upper low, from the
coast to the Cascades Wednesday morning into early afternoon
(especially Coos and Douglas counties), then east of the Cascades
(especially southern Lake County) Wednesday afternoon into early
evening.

Forecast rainfall in the 24 hours from late Tuesday night through
Wednesday evening is around a half inch to an inch for the coast
and Douglas County, a quarter to a half inch for Josephine and
Jackson counties, around a quarter of an inch for far western
Siskiyou and northern Klamath counties, and up to a quarter of an
inch elsewhere, with lowest totals in southern Siskiyou County.

&&

.AVIATION...10/12Z TAFS...IFR/LIFR ceilings and visibility along
with patchy drizzle are occurring along much of the coast this
morning, with the exception of a short stretch between Cape Blanco
and Gold Beach. MVFR/IFR may sneak into the Umpqua Basin near or
just after sunrise, but confidence is very low. These areas of low
clouds and fog will burn off by late morning or early afternoon.

Elsewhere, VFR will prevail through the day, though smoke from area
wildfires will cause areas of reduced visibility, especially in the
immediate vicinity of the fires.

A front will approach the area this evening and tonight, with MVFR
ceilings moving into the coast around and after sunset, then
becoming more widespread late tonight north and west of the Rogue-
Umpqua Divide. Precipitation will move onshore overnight, then
spread inland with a mix of VFR/MVFR and areas of higher terrain
becoming obscured in numerous showers/isolated to scattered
thunderstorms on Wednesday. -Spilde/BPN

&&

.MARINE...Updated 200 AM Tuesday, September 10, 2024...The thermal
trough will continue to produce gusty north winds and steep wind-
driven seas through today, with conditions improving in the
evening.

A cold front will approach the coast tonight, with winds shifting to
the south and rain and isolated thunderstorms moving through the
coastal waters late tonight through midday Wedensday.  Westerly
swell will build into the region late Wedensday into Thursday, but
conditions should remain below Small Craft Advisory thresholds.

The thermal trough will return Thursday afternoon, with gusty north
winds and steep seas expected into the weekend. Periods of very
steep and hazardous seas are possible south of Gold Beach. -BPN

&&

.FIRE WEATHER...Issued 230 AM Tuesday, September 10, 2024...East
side conditions today will resemble those from yesterday, with
breezy westerly winds with gusts up to 25 mph in the afternoon
and evening. A trend of cooling and higher minimum humidity will
be more noticeable from the coast to the Cascades.

An upper level low and cold front will swing over our forecast area
on Wednesday and bring wetting rain to most of our Oregon areas with
the probability of wetting rain decreasing farther to the south
and east in California. There is potential instability in the
forecast with the models showing CAPE across most of our forecast
area on Wednesday. The best chance of storms still remains in
Oregon in the center of the low, from the coast to the Cascades
Wednesday morning (especially Coos and Douglas counties), then
east of the Cascades (especially southern Lake County) Wednesday
afternoon into early evening. But, we can`t rule out activity in
California, farther to the south, or lingering afternoon activity
in southwest Oregon. The Alturas GFS BUFR forecast still shows
CAPE with a pretty dry inverted V sounding, so there is a threat
for new starts. However, we don`t anticipate the lightning to be
abundant based off of shear profiles, CAPE/Shear balance, and the
latest lightning probabilities.
-Smith/DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Small Craft Advisory until 8 PM PDT this evening for ORZ021.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 8 PM PDT this
     evening for PZZ350-356-370-376.

&&

$$
DW