Freeze Watch 8, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
236 PM PST Mon Nov 15 2021

.DISCUSSION...

.Short Term...Now Through Thursday Night...As of 2 PM this
afternoon, the cold front has just passed through North Bend, and
is moving quickly from northwest to southeast through the forecast
area. There is a narrow band of precipitation associated with
this front, fitting neatly between Crater Lake and Cape Blanco,
with decent rainfall rates being recorded in its wake. Winds have
also increased ahead of the front, with gusts over 45 mph being
recorded east of the Cascades. A Wind Advisory remains in effect
for portions of Lake County, and details can be found at
PDXNPWMFR. Snow levels will remain quite high throughout the
duration of the heavier precipitation, but will drop to Cascade
pass level as the precipitation tapers off. While some of the
peaks and higher elevations, such as the rim of Crater Lake may
get a few inches, the passes should only see a dusting to an inch
or so.

The front will pass through the area quickly, exiting to the east
overnight, leaving only a few showers along the coast and in the
northern Umpqua Basin by sunrise, and these will be associated
more with the onshore flow than the front itself. There is much
cooler air mass that will follow, with temperatures Tuesday and
Tuesday night dropping by 10 to 20 degrees over the previous 24
hours. Some frost or freeze conditions are expected in the Umpqua
and Coquille/Coos basins by Wedensday morning as a result. These
colder temperatures could be tempered a bit by easterly, offshore
flow this is likely to develop Tuesday night into Wednesday, as
high pressure builds inland and a thermal trough sets up along
the coast. Warmer temperatures are likely along the southern
coast near Brookings due to the Chetco effect, but it remain to
be seen how effective these winds will be at keeping fog out of
the valleys. We do think that the fog will be limited, but it is
possible that the winds will flow directly over the valley
inversions, and some areas will remain locked in fog for some
time.

After a quiet and dry Wednesday, the next front arrives Thursday.
We are keeping a close eye on winds with this event, as it does
appear to be one of our more typical Shasta/Rogue valley and East
Side wind-makers, but overall, the strength of the event is not
one that appears all that exceptional from our usual wet-season
systems. A few inches more snow on the Cascade passes, some
advisory level winds in the valleys and the East Side, and
additional much-need rainfall (but not excessively so) will be the
hallmarks of this event as we head into the extended term.
-BPN

Long term...Friday morning through Monday night...Gusty winds and
showery conditions will continue Friday morning and afternoon as the
system at the tail end of the short term continues to push inland.
Snow levels will bottom out at around 5500 ft behind the front
Friday morning, so only the higher Cascade passes should see any
winter impacts. Even then, we only have 1 to 3 inches in the
forecast for those elevations, with the higher amounts expected
along the Cascades north of Lake of the Woods. Winds will ease
Friday evening and showers will taper off Friday night.

Dry conditions are expected to persist through the remainder of the
forecast period as upper level ridging traverses the region during
this time. The ridge will likely be a "dirty ridge" with weak
systems brushing the northern fringes of the forecast area. This
will bring periods of increased high level cloud cover through the
weekend. However, for those of us in the region's valleys, you may
not notice much in the way of high level clouds due to the low
clouds and fog that are likely under this pattern, especially in the
mornings.

The pattern remains progressive, however, and the ridge axis looks to
be east of the area by Sunday night, leaving the region under
southwest flow. As is typical at this time range, there is
disagreement on when the next system approaches the area. A cut-off
low is forecast to be off the southern California coast Sunday night
into Monday. At the same time, a front and attendant upper level low
will approach the region from the Gulf of Alaska. How these two
features interact will determine when the next front moves through
the region. Although the deterministic GFS brings a weak front into
the region Monday, the majority of the ensembles are slower at
bringing this front inland and maintain dry conditions through
Monday for much of the area. As such, have leaned on the NBM and
limited precipitation potential to areas along the coast and Umpqua
Divide northward for Monday. /BR-y

&&

.AVIATION...15/18Z TAFs...A cold front will move into the area
today. Residual low ceilings continue to bring IFR to Medford,
but these lower ceilings should gradually lift as the front moves in
this afternoon.

Rain will accompany the front mainly from the coast to the Cascades
with MVFR becoming the predominant condition on the west side and
the freezing level falling from around 8000 ft msl to 4000 ft msl.
Expect local IFR in areas of heavier rainfall along with terrain
becoming obscured.

On the east side, VFR will persist into early this evening, but
local MVFR conditions may develop as the front moves east of
the Cascades. -Spilde

&&

.MARINE...Updated 800 AM PST Monday 15 November 2021...A strong
front will move through the region today. South winds ahead of this
front will peak late this morning into the afternoon. The majority
of models indicate that gales are likely from Cape Blanco north as
this front moves across the waters late Monday morning and Monday
afternoon. Very steep seas are expected late this morning and into
the afternoon, remaining very steep through the evening.

A thermal trough will develop behind the front this evening. Winds
will quickly become northerly and west swell should reach its peak
(10-11 ft at 10 seconds). North winds persist into Wednesday
morning, strongest south of Cape Blanco, with winds peaking Tuesday
afternoon and evening. Winds may gust to gale force for some
locations south of Gold Beach. Confidence is growing that the
pattern will remain active during the second half of the week with
the next strong front expected on Thursday. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 1 AM PST Tuesday for ORZ031.

CA...None.

Pacific Coastal Waters...
     Small Craft Advisory until 4 PM PST Tuesday for PZZ356-376.
     Small Craft Advisory from 10 PM this evening to 4 PM PST Tuesday
     for PZZ350-370.
     Gale Warning until 4 PM PST this afternoon for PZZ350-370.
     Hazardous Seas Warning until 10 PM PST this evening for
     PZZ350-370-376.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
515 PM PST MON NOV 15 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0330 PM     HEAVY RAIN       2 WSW OBRIEN            42.06N 123.73W
11/15/2021  M0.52 INCH       JOSEPHINE          OR   TRAINED SPOTTER

&&

BTL