540
FXUS66 KMFR 070426
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
926 PM PDT Sun Oct 6 2024

.DISCUSSION...Satellite imagery is showing cloud-free skies
across southern Oregon and northern California. This is resultant
of high pressure dominating our area. As such, expect the
inversion to set itself back up this evening and overnight. With
the inversion, the National Blend of Models is having a hard time
predicting morning lows for the valleys: As an example we had
forecast a low of 48 this morning for the Illinois valley, and
they got to 38 degrees. Similar conditions and forecasts occurred
in the Rogue and Klamath Valleys as well. Have adjusted the lows
to be similar to what was seen last night.

Otherwise, the forecast seems to be on track especially with the
thunderstorm threat for tomorrow. After taking a look, the 15%
slight chance seems reasonable after looking at the High
Resolution Ensemble Forecast members. -Schaaf

&&

.MARINE...Updated 800 PM PDT Sunday, October 6, 2024...North
winds will continue through Monday morning with steep wind driven
seas to the south of Gold Beach and beyond 10 NM from shore.
Meantime, longer period swell will build, increasing surf and
breaking action around bars.

Later Monday, winds will ease and the swell period will begin to
shorten. Swell dominated seas will remain moderate Monday night
through Wednesday. Winds will remain below 20 kts from mid to late
week, but Small Craft Advisory seas are possible again, starting
around Friday night due to building northwest swell.
-DW


&&

.PREV DISCUSSION... /Issued 455 PM PDT Sun Oct 6 2024/

..Updated the aviation section...

DISCUSSION...As of 2 pm Sunday...Temperatures were generally
running between 2 and 7 degrees warmer compared to 24 hours ago as
an upper level ridge of high pressure builds over the Pacific
Northwest. Temperatures are expected to continue to climb into the
late afternoon hours and end up generally 10 to 15 degrees above
normal for the beginning of October.

The upper ridge will shift slightly east over the next 24
hours...however temperatures are expected to be nearly identical
to those observed today. An upper level shortwave is forecast to
move northeast from northwest California into south central
Oregon Monday late morning into the afternoon hours. This is
forecast to trigger thunderstorms across a line generally from
just south of Yreka northeast toward Bly late Monday
afternoon...and continue moving northeast toward Paisley in
central Lake county by the evening hours. Confidence isn`t very
high...the chance of precipitation is generally 20% to 30% with a
slight chance (15% to 20% chance) of thunderstorms. The most
likely area to experience thunderstorms will be in and around
Alturas...as a few of the high res models are highlighting that
area.

After the brief chance of thunderstorms...the area will be
dominated by upper level southwest flow allowing seasonable
temperatures to return to the area mid week into at least the
first half of the weekend. There is still quite a bit of
uncertainty in the extended forecast...both with any chance of
precipitation as well as the temperature forecast.

About 60% of the ensemble members indicate precipitation for the
area generally along and west of the Cascades...with the highest
chance being right along the coast. Unfortunately about 40% of
the members indicated in the clusters...keep the upper trough too
far west...with the ridge firmly in place over the forecast area.
This is also seen in the spread of potential temperatures...using
Medford as an example...temperature values range anywhere from the
low 70s to mid 80s on Friday.

With all of the uncertainty...please continue to monitor the
forecast for the latest information. We will remain hopeful for a
change in the weather pattern!

-Riley

AVIATION...07/00Z TAF...With one exception, VFR conditions and
relatively light winds are expected to persist through Monday
afternoon. Patches of stratus with LIFR cigs and vis will return to
the coast late this evening into early Monday morning. There is also
a slight chance (20%) of some stratus intrusion into the Coquille
and Umpqua basins (including Roseburg) late tonight. On Monday
afternoon, a slight chance (15%) of thunderstorms will develop over
portions of the east side...south and east of Klamath Falls. -DW

FIRE WEATHER...Updated 100 PM Sunday October 6, 2024...The overall
trend of dry conditions with seasonably cool mornings that give way
to late summer like temperatures will continue through Monday.
Daytime humidities will also resemble more summer like values, and
recoveries will continue to be moderate to poor again Monday
morning. Westerly winds will be slightly enhanced east of the
Cascades the next few afternoons, and with low daytime humidities,
conditions could approach critical today and Monday afternoons.
Additionally, shortwaves will pass around the northwestern periphery
of the high pressure centered over the southwest. This will result
in cumulus buildups across portions of the Modoc and into
southeastern Lake County today and again Monday. There could be a
stray shower (5-10% chance) in those areas this afternoon, but
moisture looks more sufficient on Monday. We`ve included showers and
isolated thunderstorms (10-20% chance) roughly from the Medicine
Lake area northeastward into far SE Klamath and southern Lake
Counties and over much of Modoc county.

The pattern starts to shift on Tuesday as a shortwave trough moves
through the region, pushing the ridge farther east and breaks it
down. This will bring improving recoveries and a subtle cooling
trend with daytime humidities trending higher through the remainder
of the week. Dry conditions will continue until the end of the week
when a front approaches the region. There remains considerable
differences among the models and ensembles on where and how much
precipitation will occur during the Friday-Saturday timeframe. As is
usual, the better chances are for the Cascades westward, with
confidence and chances decreasing the farther east you go. /BR-y

&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Monday
     for PZZ356-376.

&&

$$