Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 081655

Area Forecast Discussion
National Weather Service Medford OR
855 AM PST Thu Dec 8 2016

.DISCUSSION...Precipitation is starting to decrease from southwest
to northeast this morning. However still could not rule out light
snow and pockets of freezing rain this morning. This is especially
east of the Cascades where the warmer air loft has not quite moved
in and it could take a while for that to happen. A quick look at
some of the short range models show the bulk of the precip moving
north later this morning with showers starting to move in along
the coast later this afternoon. However by then snow levels will
be higher and the colder air should already have been scoured out
in the deeper valleys west of the Cascades, so were not expecting
any concerns on that front.

The end time for the ice storm warning and winter weather
advisories west of the Cascades in Oregon look good and we`ll let
them expire. Elsewhere the end times also look good.

The pattern will remain rather active for the foreseeable future.
We may get relative breaks in the action, but confidence of when
and how long they will be is low. -Petrucelli


.AVIATION...08/12Z TAF CYCLE...A warm front lifting north of the
area this morning is causing widespread MVFR with local IFR across
northern California and over the East Side with occasional light
snow. An airport weather warning is out for KLMT until 10 am for
snow (2 to 4 inches) before snow changes to mixed precip this
morning, then rain showers as temperatures get above freezing
this afternoon. North of the Siskiyous and west of the Cascades,
overall, a mix of VFR/MVFR ceilings with terrain obscured today
through tonight. IFR is expected in the valleys late tonight. A brief
period of low-level wind shear is possible 16-22z at KOTH with light
southeast surface winds and south-southwest winds of 40-45 kt about
2000 ft AGL. Winds will be gusty in the Shasta Valley and over the
East Side this afternoon into tonight. -Spilde


.MARINE...Updated 300 AM PST Thursday 8 December 2016...A warm
front will lift northward through the waters this morning into
early this afternoon. East to southeast winds will become south
and increase to gales with seas becoming steep to very steep and
wind dominated. A cold front will follow tonight with winds shifting
to southwest and easing below gales. Seas will remain steep
south of Cape Blanco and very steep north of Cape Blanco tonight
through Friday.

Seas are expected to transition to west swell Friday night into
Saturday. 00z guidance has backed off on the swell with
significant wave heights about 3-5 feet lower compared to 24 hours
ago. The storm generating the swell is forecast to be weaker and
farther north, which would keep the largest swell off to the
north. Since this is a relatively new development, have only lowered
the seas slightly and maintained the hazardous seas watch. Will
allow day shift to see the new 12z model guidance to determine if
the downward trend continues and any adjustments are necessary.

Calmer conditions are expected Sunday into early next week, but the
storm track may become active again later next week. -Spilde


.PREV DISCUSSION... /Issued 550 AM PST Thu Dec 8 2016/

DISCUSSION...Freezing Rain potential still exists this morning
for most of our forecast area except the coastal counties.
Overnight snowfall was heaviest in Siskiyou County, especially in
the interstate 5 corridor. Spotters reported in 3 to 4 inches of
snow until around midnight. Roadcams also show snow over the
Cascades and Siskiyous as well as Klamath and Lake Counties. This
morning sounding shows the a warm layer above freezing temperature
is starting to push into southern Oregon. Temperatures at the
Rogue Valley airport has moved above freezing but there were
reports of freezing rain earlier in the Jacksonville area. There
are still pockets of cold air in the area, especially in the
Illinois Valley and Douglas County, but by mid morning we expect
surface temperature to warm above freezing.

As of 4 AM temperatures in the Scott Valley and northern half of
the Shasta Valley were still a few degrees F below freezing. Those
areas and the Klamath River Valley are still under threat for
freezing early this morning.

Elsewhere south winds are starting to increase at Weed and we
expect winds to continue to increase this morning, peaking early
to middle afternoon. The stronger winds will help scour out cold
air in the southern end of the Shasta Valley.

The warm front is expected to lift north into central Oregon this
evening but the cold front will be slow to move inland. This
allows H700 mb winds to mix down and will be felt mainly east of
the Cascades. The High Wind Watch for the east side has been
upgraded to a High Wind Warning. The cold front is forecast to
move inland Friday and through our forecast area into western
Nevada Friday night. Onshore flow and instability will keep
showers in the area but snow levels will rise to around 5500-6000


OR...High Wind Warning from 1 PM this afternoon to 1 AM PST Friday
     for ORZ030-031.
     Winter Weather Advisory until 4 PM PST this afternoon for
     Winter Weather Advisory until 9 AM PST this morning for
     Winter Weather Advisory until 1 PM PST this afternoon for
     Winter Weather Advisory until 1 PM PST this afternoon for

CA...High Wind Warning from 1 PM this afternoon to 1 AM PST Friday
     for CAZ085.
     Winter Weather Advisory until 1 PM PST this afternoon for
     Winter Weather Advisory until 1 PM PST this afternoon for
     Ice Storm Warning until 9 AM PST this morning for CAZ080.
     Wind Advisory until 4 AM PST Friday for CAZ081.
     Winter Weather Advisory until 1 PM PST this afternoon for
     Winter Weather Advisory until 10 AM PST this morning for CAZ085.

Pacific Coastal Waters...Small Craft Advisory until 4 PM PST Friday for PZZ350-356-376.
     Hazardous Seas Watch from Friday afternoon through Saturday
     afternoon for PZZ350-356-370-376.
     Gale Warning until 4 PM PST this afternoon for
     Small Craft Advisory for hazardous seas from 4 PM this afternoon
     to 4 PM PST Saturday for PZZ356.
     Hazardous Seas Warning from 4 PM this afternoon to 4 PM PST
     Friday for PZZ350-370.

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