713
FXUS66 KMFR 180944
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
244 AM PDT Wed Sep 18 2024

.DISCUSSION...A low is moving south along the northern California
coast and will continue to shift southward today. Scattered
showers are continuing overnight, with the best chances (40-60%)
of showers along and near the Cascades and into northern
California as well as along the coast and into the Umpqua. Shower
activity with diminish in the morning hours as the low shifts
south. Models remain on track showing scattered showers across
northern California this morning, becoming isolated in the
afternoon. There is a slight chances (15%) for thunderstorms as
well this afternoon in southern Modoc County and a low (10%)
chance for thunderstorms in southwest Siskiyou County. Otherwise,
expect mild temperatures. Lingering moisture will result in areas
of low clouds and valley fog tonight and Thursday morning, mainly
along the coast from Cape Blanco north and into the Umpqua basin.

High pressure will build into the area tonight and Thursday then
remain in place through late in the week. This will result in a
warming trend with mild morning lows and warm (slightly above
normal) afternoon highs. Breezy to gusty (north to northwest)
afternoon winds are expected Thursday and Friday. Tonight through
Friday night, a thermal trough along the coast will also result in
breezy northeast winds in the overnight hours for the coastal
mountains and for the mountains in western Siskiyou. With this
pattern, humidities will gradually trend drier but we are
currently not expecting critical fire weather conditions.

On the weekend, expect high pressure to remain in place. A couple
weak upper level disturbances will move over the ridge and into
the area late Saturday and Sunday. Models favor continued dry
weather with temperatures remaining above normal through the
weekend. Then high pressure is forecast to strengthen and
temperatures trend higher early next week. Mid week, ensembles
are indicating an upper level trough and weak front may move into
the region (around Tuesday night into Wednesday). This is
expected to bring a slight chance (10-20%) for showers to
far northwest portions of the area and allow for temperatures to
trend less warm.


&&

.AVIATION...18/06Z TAFS...Showers will gradually taper off overnight
into 18Z Wednesday morning. Conditions will remain mainly VFR, but
areas of MVFR ceilings and visibilities and mountain obscuration
will continue in the vicinity of showers. Residual low level
moisture is also expected to aid the formation of MVFR for the coast
and Umpqua Valley from around 08Z to 20Z. -DW

&&

.MARINE...Updated 245 AM Wednesday, September 18, 2024...Stable
atmospheric conditions are expected to build a persistent thermal
trough today into the weekend. Northerly winds will build steep seas
south of Cape Blanco by this evening, with steep seas then moving
into northern waters through at least Friday. Areas of very steep
and hazardous seas are possible south of Pistol River through Friday
as well. A Hazardous Seas Warning is in place for Thursday afternoon
through Friday evening for current areas where very steep seas are
expected. The area has been trimmed, but additional guidance will
help to solidify the timing and area of these conditions.

Elevated steep to very steep seas look to continue through the
weekend and into next week, with gusty northerly winds.
-DW/Hermansen


&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM Thursday to 5
     PM PDT Friday for PZZ350-370.

Small Craft Advisory from 5 PM this afternoon to 5 PM PDT Friday
     for PZZ356-376.

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

&&

$$

CC