High Wind Watch 4, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
847 AM PST Tue Jan 10 2023

.DISCUSSION...Despite the very busy appearance on radar very
limited amounts of precipitation has fallen in the area, except in
the Mt. Shasta region. Around Mt. Shasta, between 0.1" and 0.2"
has been observed in the area in the last six hours. Everywhere
else, less than 0.05" has fallen and that's mostly in the
Siskiyous.

Winds will also continue to ease through this afternoon from the
30+ mph wind gusts observed over the ridges and in some west side
valleys last night. The exception to this is along the Curry
coast, where south winds will continue to blow, with gusts above
30 mph along the beaches and capes.

Despite all the cloud cover and lack of steady sunlight,
temperatures will be on the warmer side today. In the west side
valleys max temperatures should run 3-5 degrees above normal for
January. East of the Cascades temperatures will be around normal.
These seasonal temperatures are thanks to a temperate airmass that
has slowly built in from all of these southerly oriented frontal
systems.

More weather systems will move through this week. The next one is
expected tonight. This will bring renewed gusty winds for the
whole region, heavy snow in NorCal and light but steady
accumulations in the Cascades and East Side. More details on this
system and the ones to follow are in the previous discussion
below.
-Miles

&&

.AVIATION...10/12Z TAFs...VFR conditions prevail across the region
early this morning, except for LIFR fog and freezing fog in western
and northern portions of the Umpqua Valley.

The next front will move northeast through the area today with gusty
southerly winds, and areas of low level wind shear through around
19Z, late this morning. It will also produce areas of mountain
obscuration and MVFR with precipitation mainly from the Siskiyou
Mountains southward across northern California. Freezing levels
around 7000 feet msl are expected to fall to 5000 feet msl tonight.
/DW

&&

.MARINE...Updated 800 AM PST Tuesday, January 10th 2023...Steep to
very steep and hazardous seas will diminish slightly this morning.
The initial portion of the Gale Watch has been upgraded to a Gale
Warning and updated for a faster approach of a frontal system.
Winds increase this afternoon then gales will begin early this
evening with seas building to a peak around midnight.

The next strong frontal system will follow closely behind. The warm
front will lift north over the area Wednesday, then the cold front
will stall just offshore late Wednesday and Thursday. This is likely
to result in strong south gales and very steep seas across the
waters early Wednesday through Thursday. Seas will peak on Thursday
night with very high and very steep seas. During Thursday afternoon
through Thursday night, a long period, heavy west swell is forecast
to build into the waters and combine with south-southwest wind seas.
This will create dangerous mixed seas. -BR-y/DW

&&

.PREV DISCUSSION... /Issued 420 AM PST Tue Jan 10 2023/

SYNOPSIS...A strong upper level low pressure system in the Gulf
of Alaska will continue to send a parade of disturbances across
the US West Coast as it meanders within the Gulf of Alaska. These
disturbances so far have provided for significant rain and
snowfall in northern California and wind in southern Oregon. This
is expected to continue our active weather streak through much of
the forecast period.

*Snowfall in northern California could lead to difficult to
 potentially dangerous travel conditions, especially above 3500
 feet today and 4000 feet on Wednesday.
*Strong winds will continue across many southern Oregon and
 northern California locations. This could lead to isolated power
 outages and trees or their limbs to fall.
*Moderate rain at the coast could continue to create isolated
 travel difficulties.

DISCUSSION...Radar is starting to show the first showers in the
next system moving northward entering Siskiyou County. With the
general south to north flow, expect terrain influences (namely,
Mt. Shasta) to enhance precipitation with the upslope flow, and
produce periods of moderate snows today. Snow amounts today will
be between 2 and 4 inches across portions of Interstate 5 near
Black Butte Summit and across portions of US 97 in California.
Higher amounts of 5 to 9 inches are possible along Highway 89 at
Snowman Summit, Highway 3 south of Callahan, and Sawyers Bar Road
near Mt. Etna. A winter weather advisory for these areas begins at
4AM, and will continue through 4pm today. This seems reasonable,
and will allow it to continue. Please see the WSWMFR for more
details.

In addition, conditions will become breezy to windy for our
north-south oriented valleys (Shasta, southern end of the Rogue
Valley) as well as for some of our higher terrain in the
Siskiyous, Cascades, and the Marble Mountains. Later this
afternoon and evening, expect conditions near the coast and the
coastal headlands to become breezy. Right now, we will continue
wind advisories for the Shasta and the southern edge of the Rogue
Valley which remain in effect through 10 AM PST. For more
information, please see the NPWMFR for more details.

In Oregon, expect cloudy skies, and temperatures a few degrees
cooler. Some light precipitation is expected across portions of
the area in the afternoon and evening, focusing mostly on terrain,
especially in the Coastal Range. Still impacts from rain will
largely be isolated in nature.

This pattern will be repeated once again as the next system
approaches Wednesday morning. Early Wednesday morning will come
with a breezy start in the southern Rogue and Shasta Valleys with
gusts reaching 30 mph. As the front approaches, the winds will
pick up along the coast and area-wide ridges. Winds along the
coast will come close to High Wind Warning Criteria and with the
Shasta and Rogue Valleys approaching Wind Advisory Criteria. We
will continue to evaluate the need for issuing wind hazard
products in the coming shifts, but with the ongoing hazards, will
hold off for now.

As far as precipitation is concerned, the Wednesday system will
bring higher precipitation amounts to southern Oregon and northern
California. snow levels will start around 4,000 feet and rise to
5,000+ feet. Before snow levels rise above 5,000 feet, impactful
snowfall amounts will be possible in parts of the Cascades and
parts of Northern California. With winter headlines out currently,
any winter hazard products will be issued on later shifts. -Schaaf

PREVIOUS LONG TERM Issued 1/9/23 and slightly
modified...Wednesday night, January 11 through Monday, January 15,
2023...A cold front will near the coast Wednesday night into
Thursday. Models and ensembles continue an upper trough deepening
offshore while an upper level ridge builds inland. As a result,
the cold front is expected to remain stalled just off the PacNW
coast. Although the newest guidance has trended the winds down a
little bit, we can still expect gusty winds over the area as a
lower level jet moves over the coast and a mid level jet moves
into the area late Wednesday into Thursday. Strong winds are
likely across the coastal waters beyond 10 nm. Moderate to strong
winds are possible along the coast and inland over the mountains
and into the Shasta and southern Rogue valleys.

With the cold front remaining offshore, expect most the
precipitation (generally light to moderate) to occur along the
coast, coastal mountains and at times, into southwest Joesphine
and western/southern Siskiyou County from Wednesday night through
Friday. Depending on the position of the front as it remains
offshore, there may be short breaks in the precipitation, even at
the coast, especially late Thursday into Friday.

The pattern becomes more progressive Friday night into Saturday, as
an upper level low and trough arrive and become positioned off the
PacNW coast. With this pattern, the front is expected to push
onshore Friday night into Saturday.  Then another low pressure
center and frontal system will track towards the area from the west
or  northwest. This system may move into northern California though,
keeping lighter precipitation over southwest Oregon and a potential
for moderate precipitation across N. California zones. However,
ensembles continue to show variable solutions with the track of this
system, so confidence is low in the details for this period.  There
is higher confidence that the ridge will break down though on
Saturday with an upper trough moving inland late Saturday. Also,
snow levels are likely to be high on Saturday, around 5000 ft or
higher, lowering to around 4000 ft Saturday night into Sunday.
Sunday into early next week, a westerly pattern aloft sets up with
additional storm systems likely to move into the area. -CC

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 10 AM PST this morning for ORZ026.

     High Surf Warning from 10 AM Thursday to 4 AM PST Friday for
     ORZ021-022.

CA...Winter Weather Advisory until 4 PM PST this afternoon above 3500
     feet for CAZ080>083.

     Winter Storm Watch from 4 PM PST this afternoon through
     Wednesday afternoon above 4000 feet for CAZ080-082-083.

     Wind Advisory until 10 AM PST this morning for CAZ081.

PACIFIC COASTAL WATERS...High Surf Warning from 10 AM Thursday to 4
     AM PST Friday for PZZ350-356.

     Small Craft Advisory until 4 PM PST this afternoon for PZZ350-
     356-370-376.

     Gale Warning from 4 PM this afternoon to 1 AM PST Wednesday for
     PZZ350-356-370-376.

     Gale Watch from late tonight through Thursday evening for PZZ350-
     356-370-376.

&&