Small Craft Advisory 4, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
923 PM PST Wed Jan 9 2019

UPDATE...Showers will continue this evening and into tonight,
but rainfall amounts will be light. Precipitation is expected to
taper off through the early morning, and should come to an end by
midday tomorrow. With snow levels hovering between 5000 and 5500
feet through this time, no major road or travel impacts are
expected.

No forecast updates are needed this evening, as everything appears
to be in line with the current observations and trends. For more
information on the rest of the forecast, see the previous
discussion below. -BPN

&&

.AVIATION...For the 10/06Z TAFs...Winds have shifted toward the
southwest at the terminals, and will continue to gradually weaken
through the evening as the passing cold front dissipates. Rain
showers in the area will break up as they move farther inland, and
rain will be spotty around Medford and from the Cascades east this
evening with VFR conditions likely continuing. Expect occasional
mountain obscurations through tonight. Should there be any clearing
behind the front tonight, there could be areas of IFR/LIFR that
develop in the west side valleys, like Medford and Roseburg. Low
ceiling would be the most likely aviation hazard, but can't rule out
fog either. Any areas that develop low ceilings or visibilities
overnight should clear by afternoon. -Wright/BPN

&&

MARINE...Updated 800 PM PST Wednesday, 9 January 2019...A
combination of southwest swell and fresh wind seas will produce very
steep and hazardous seas for much of the region through this
evening. As a result, bar crossings and surf conditions will remain
hazardous through tonight. Conditions slowly improve Thursday into
Friday, but seas will likely remain high and steep with periods of
gusty south winds into early next week as more fronts move through
the region.

Also of note, very long period swell is forecast to build into
the region late Saturday into Sunday. While overall wave heights
are only forecast to reach around 13 feet, periods will be in the
range of 25 seconds or more, and this could produce erratic near-
shore currents and hazardous bar conditions through the weekend.
-BPN/Spilde

&&

PREV DISCUSSION... /Issued 251 PM PST Wed Jan 9 2019/

SHORT TERM...

Breezy conditions will continue this afternoon and evening as a
low over the Pacific moves towards the Canadian coastline. Because
of this low moving farther away, winds should be on the down
trend this afternoon and evening west of the Cascades. East of the
Cascades, our usual windy spots like Summer Lake and the Summit
RAWS will still produce gusts up to 50 mph this evening.

As for precipitation, we're expecting more of that to fall along
the coastal range and in southern Siskiyou county. Mount Shasta
has been reporting rain all day with 24 hours accumulations around
2 to 3 inches. We haven't heard of any flooding impacting the
public, but its still within reason that small streams will have
higher flow with the some snow melt added in.

Heading into Thursday and Friday, we'll see high pressure build in
and the return of the valley fog. Right now, our forecast has
above freezing temperatures for most of the valleys, so we're not
expecting freezing fog at this time. Eventually, some upper level
energy will try and break down this ridge, but fail. We'll only
see a slight chance for rain along the southern coast and northern
California Friday night into Saturday morning. We'll likely see
under 0.1 inches of rain during the time period mentioned above.

Overall, no significant weather impacts expected after this
afternoon. The fog has been known to cause driving and flying
issues, but it's not always clear how dense it will end up being.

-Smith

LONG TERM...
Long term discussion from the Tuesday afternoon AFD...Saturday 12
January through Tuesday 15 January 2019. The models are in
excellent overall agreement, both with each other and with their
ensembles, through the extended period. This gives unusually high
confidence to the long term forecast.

A strong upper level ridge will be centered over the rockies on
Saturday. A front will attempt to come onshore Saturday but is
expected to dissipate as it runs into the ridge. The best chance for
rain from the front itself will be over our coastal waters and the
south coast. Even though the front dissipates, moist southerly flow
continues, and this also keeps rain chances going in the upslope
areas of Siskiyou County Saturday. Elsewhere, spotty light
precipitation can't be ruled out. Saturday's front does help bump
the upper ridge slightly further east, which then opens the door for
the next front Saturday night and Sunday. This front also weakens as
it encounters the upper ridge inland, but it should bring some
precipitation to all of the west side. While amounts will not be
anything to write home about, pops were raised. The upper ridge
finally moves far enough east to allow the next system to come in
largely unfettered on Tuesday. This one looks to produce more
significant precipitation and probably some wind impacts as well.
The forecast for Tuesday was adjusted accordingly. Finally, all
guidance, including ensembles, suggests wet and unsettled weather to
continue for the remainder of next week as a very large trough sets
up over the northeast Pacific.

-Wright

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 10 PM PST this evening for ORZ030-031.
     High Surf Advisory until 10 PM PST this evening for ORZ021-022.

CA...Wind Advisory until 10 PM PST this evening for CAZ085.
     Flood Watch until 10 PM PST this evening for CAZ080>083.
     Wind Advisory until 10 PM PST this evening for CAZ081.

Pacific Coastal Waters...Small Craft Advisory until 10 AM PST Friday for PZZ350-356.
     Hazardous Seas Warning until 10 PM PST this evening for
     PZZ350-356.
     Small Craft Advisory until 10 AM PST Friday for PZZ370-376.
     Hazardous Seas Warning until 10 AM PST Friday for PZZ370-376.