Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 050339
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
839 PM PDT Wed Oct 4 2023

.UPDATE...The forecast is on track for tonight. Conditions are
calm as an upper level ridge moves eastward over the area. Thursday
is forecast to be 5-10 degrees warmer than yesterday for most
inland areas. Patchy fog and low level clouds may develop in the
Umpqua Valley or along the coast north of Cape Blanco overnight,
but should clear out before the afternoon. Otherwise, clear skies
and light winds are expected through the day. -TAD


&&

.AVIATION...05/00Z TAFS...VFR conditions will persist across
northern California and southern Oregon through the evening and into
Thursday morning. Early Wednesday morning, IFR ceilings and MVFR to
IFR visibilities are expected to drop to IFR levels in the Umpqua
Valley and along the Oregon coast north of Port Orford. Other deeper
west side valleys and sheltered areas may also see lowered
visibilities and ceilings. Any lowered levels are expected to clear
up by late Thursday morning.

In general, all other areas are expected to stay at VFR through the
TAF period. Isolated areas of patchy fog are also possible in the
Rogue Valley, but confidence is not high enough in that condition to
include in the TAFs. -TAD


&&

.MARINE...Updated 815 PM October 4, 2023...Moderate to strong
winds will continue through Thursday morning as a thermal trough
remains along the south Oregon coast. The strongest winds and
highest seas are expected from Cape Blanco south. There could be
brief periods of times where winds gusts could exceed gales from
Gold Beach southward and beyond 3 nm from shore. North of Cape
Blanco, expect mainly steep seas and moderate winds.

Winds gradually lower tonight into Thursday but expect lingering
steep to very steep seas through at least Thursday morning. Beyond
Thursday, north winds weaken further as the thermal trough expands
northward and conditions improve for all areas late week into the
weekend. A change in the weather pattern is expected for early next
week as a front impacts the waters by Monday. This would bring
increasing south winds as well as an incoming west swell. /BR-y


&&

.PREV DISCUSSION... /Issued 214 PM PDT Wed Oct 4 2023/

..Updated AVIATION discussion...

DISCUSSION...Recent satellite loop is showing the last of the
clouds burning off early this afternoon with pretty much wall to
wall sunshine area wide. Upper ridging offshore will continue to
build into the area through late week. A surface thermal trough in
NorCal is expanding northward into SW Oregon and will continue to
do so through Friday. This brought gusty ENE winds over the
coastal and northwestern Siskiyou County upper slopes/ridges last
night into this morning. These winds continue to descend through
the Chetco River Valley. Compressional warming has sent the
temperature well into the 80s at Brookings (86F as of 2 pm), while
immediate coastal areas to the north remain in the mid to upper
60s -- a nice representation of our local "Banana Belt". Inland,
after the clouds earlier, we`ll warm up with the sunshine this
afternoon, about 5-10F over yesterday`s highs. This puts us into
the low 80s here in Medford and in the 70s over the East Side/NE
California. Valleys of western Siskiyou County will be warmest
with highs in the 80s to near 90F.

With the strong ridge expected to be over the area the rest of
this week and even into this weekend, we are expecting an extended
period of dry, warm, fall weather. High temperatures will be
about 5-15F above normal, with the peak of the warmth focused on
Friday west of the Cascades (highs in the upper 80s to near 90F here
in Medford) and on Saturday east of the Cascades. It will be warm
again along the SW Oregon coast on Thursday (Brookings again
probably up into the 80s). On Friday, offshore flow will probably
result in some of the warm weather reaching coastal areas farther
north than usual (North Bend) with highs in the upper 70s to the
low 80s.

A southerly surge of stratus/fog could begin to move up the coast
from the south as early as Thursday night/Friday, but especially
Friday night into Saturday. Onshore flow will start in the south
(it will cool off in Brookings Friday), and there may even be some
drizzle eventually over the weekend at coastal locations, but
still no significant precipitation.

That will change by early next week. We have high confidence in a
strong frontal system and associated atmospheric river moving
into the area Monday and Tuesday with a high probability (>60%
chance) of greater than 0.50 of an inch of rain for many areas
near and west of the Cascades. There is also a significant
probability (60-80%) of greater than 2 inches of rain (ending 12z
Wednesday) for coastal areas. This isn`t atypical for this time of
year for the coast, but will be a change from the dry, warm
weather expected the rest of this week into this weekend. Since
we`re getting to the time of year that we start looking for snow
impacts, it is notable that this system isn`t very cold. Snow
levels are expected to bottom out in the 7000-8000 foot range,
above all except the highest peaks in our CWA. Temperatures are
likely to cool off significantly during this time period with
highs about 5-10F below normal (in the upper 60s to low 70s west
of the Cascades; upper 50s over the East Side). -Spilde

FIRE WEATHER...Updated 200 PM October 4, 2023...High pressure
will remain over the area into the weekend bringing a warming and
drying trend.

A surface thermal trough will continue to bring breezy to gusty
northeast flow across the mountains, from the Cascades west tonight
with moderate ridgetop recoveries.  As the thermal trough builds
north Thursday night and Friday winds will decrease along the
coastal mountains and western Siskiyou County but continue to be
breezy to gusty across the Cascades Mountains. Expect moderate
recoveries over the ridges and dry daytime humidities across inland
areas Thursday night and Friday.  The easterly winds over the
Cascades will lower Friday afternoon into Saturday. Breezy easterly
winds and dry humidities are expected in the afternoons east of the
Cascades Thursday and Friday.

Dry and very warm conditions will continue across inland areas
Saturday and Sunday. Early next week, models continue indicate
another moist frontal system will gradually move into the area
late Monday into Monday night with a trough and showery pattern
on Tuesday. Ahead of the front, expect gusty south to southwest
winds and dry humidities, east of the Cascades Sunday afternoon with
gusty winds again Monday afternoon. The front will likely move
onshore during the day Monday, with precipitation gradually
spreading inland Monday afternoon through late Monday night.
Moderate to heavy rain is likely along the coast, mountains and
into the mountains in western Siskiyou with a 60-90 percent chance
for an inch of rainfall (Monday through Monday night) with moderate
rainfall for many areas inland to the Cascades and light to locally
moderate rainfall east of the Cascades. -CC

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT
     Thursday for PZZ350-356-370.

Hazardous Seas Warning until 11 AM PDT Thursday for PZZ356-370-
     376.

&&

$$


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