High Surf Warning 3, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
855 AM PST Mon Nov 18 2024

.DISCUSSION...An upper trough over the area is bring a moist,
cold unstable airmass with numerous showers from the Cascades west
and scattered showers east of the Cascades. Snow levels have
lowered down to near 2000 feet but locally have had some occur
down to near 1500 ft. Snow levels are forecast to rise slightly
to 2500 feet to 3000 ft this afternoon. Snow at the lower
elevations has been mainly light and with warmer road temperatures
expect any snow that falls to melt. Over the mountains and higher
passes, moderate to heavy snow is expected in showers today,
especially over the Southern Oregon Cascades, Siskiyous and
mountains of western Siskiyou County. A winter storm warning
remains in effect through this evening for snow impacts across the
mountains. Additionally, with the cold and unstable air mass,
there is a continued risk for isolated thunderstorms over the
coastal waters, and inland along the coast, coastal mountains and
into some inland areas west of the Cascades today a.

Shower activity will decrease in coverage and intensity this
evening into tonight over the mountains and east side. However,
models show another band of precipitation spreading inland from
the coast bringing light to moderate showers into the area tonight
and Tuesday morning.

Then a moist and powerful front arrives Tuesday afternoon through
Wednesday. This is an unusually strong and moist storm and there
is high confidence for very high wind impacts along the coast and
coastal waters (hurricane force wind gusts) and moderate to
strong winds affecting inland areas as well. Additionally, heavy
rain is forecast, especially along coastal areas, and heavy snow
is likely in to the mountains and Mount Shasta City area. Heavy
rain will bring a potential for flooding (especially west of the
Cascades for small streams and some mainstem rivers). Heavy snow
and high winds over the mountains will bring potential for trees
down and dangerous travel conditions. Additionally, the potential
of heavy, wet snow in the Mount Shasta City area, including
portions of Interstate 5, may create added high impacts for the
communities in that area with a potential power outages, tree
damage and significant travel impacts. High wind watches and
Winter storm watches are in effect for the areas that will see the
highest impacts. We will be looking to update these today and
potentially adding advisories to other areas that will see
moderate snow and/or strong winds.

&&

.AVIATION...18/12Z TAFS...Ongoing showers are bringing a mix of
low end VFR and MVFR ceilings, lowest in showers, along with
widespread terrain obscurations. Not much change in these
conditions are expected through the afternoon as showers continue
through then. Freezing levels will hover around 2500 ft today.
Shower activity will diminish east of the Cascades this evening,
but continue along and west of the Cascades. Winds will turn
southerly late this evening and overnight Monday in advance of a
strong front expected late day Tuesday. Expect increasing low
level wind shear concerns just beyond the current TAF period.
/BR-y

&&

.MARINE...Updated 200 AM PST Monday, November 18, 2024...Steep to
very steep and hazardous seas will persist through this afternoon
with another heavy west swell in place. Seas will peak in the 15-20
foot range with dominant wave period of 13 seconds. Gusty west to
northwest winds will continue with scattered showers and isolated
thunderstorms into this afternoon. Conditions will briefly improve
this evening and overnight as swell subsides, but seas will remain
high and steep.

This improvement will be short-lived with conditions expected to
rapidly deteriorate by Tuesday afternoon. A surface low pressure in
the NE Pacific will deepen rapidly as it heads NE just outside 130W.
This system will "bomb out" (a pressure drop of 24 mb or more in 24
hours) with a large portion of members indicating the pressure
dropping below 950 mb as it reaches 46N and 132W by Tuesday evening.
This will send a very strong cold front and associated atmospheric
river toward the coast, impacting the marine waters. These solutions
have been consistent over the last couple of days, leading to high
confidence in dangerous conditions. There is high confidence in high
end storm force winds (45-60 kt with gusts of 65 to 70 kt) and very
dangerous mountainous seas of 30 to 35 feet. There is increasing
confidence for the potential of hurricane force wind gusts (70 to 80
percent chance). The Storm Watch has been upgraded to a warning for
all areas , and given the consistency and agreement in the model
data regarding Hurricane Force winds/gusts, there could be further
updates to the warning headlines in the future.

Mariners should expect dangerous wind and sea conditions to persist
through at least mid week with hazardous conditions possible through
Friday. Keep checking back here for updates. BPN/BR-y

&&

.BEACH HAZARDS...Updated 245 AM PST Monday, November 18, 2024...
Large, west swell will maintain breaking waves of 20 to 23 feet and
dangerous conditions to coastal areas/beaches through this
afternoon. Seas will lower slightly tonight but a strong frontal
system will move through Tuesday into Wednesday bringing building
seas with high surf conditions likely again. Models support advisory
conditions at a minimum, but with storm force south winds expected,
this could result in warning level conditions, especially at south-
facing beaches and ports. Please exercise extreme caution if you are
planning to head to the beaches or even just take a trip to the
coast through midweek. Be aware that conditions will be very
hazardous with dangerous surf conditions much of the time and
beaches should be avoided.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning until 10 PM PST this evening for ORZ025-027-
     028-030.

     Winter Storm Watch from Tuesday afternoon through Wednesday
     evening for ORZ027-028.

     High Wind Watch from Tuesday afternoon through Wednesday morning
     for ORZ021-022-024-030-031.

     High Surf Advisory until 4 PM PST this afternoon for ORZ021-022.

CA...Winter Storm Warning until 10 PM PST this evening for CAZ080-083-
     085.

     Winter Storm Watch from Tuesday afternoon through Wednesday
     evening for CAZ080-082-083.

     High Wind Watch from Tuesday afternoon through Wednesday morning
     for CAZ081-085.

PACIFIC COASTAL WATERS...High Surf Advisory until 4 PM PST this
     afternoon for PZZ350-356.

     Hazardous Seas Warning until 4 PM PST this afternoon for PZZ350-
     356-370-376.

     Small Craft Advisory from 4 PM this afternoon to 10 AM PST
     Tuesday for PZZ350-356-370-376.

     Storm Warning from 10 AM Tuesday to 10 AM PST Wednesday for
     PZZ350-356-370-376.

&&

CC