High Wind Watch 17, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
941 AM PST Sat Nov 11 2017

.AVIATION...11/18Z TAF CYCLE...General onshore (southwest) flow
ahead of an approaching front will keep a fair amount of clouds
over our area today. There are some low clouds and fog around this
morning, especially over inland valleys, but that will break up
through the morning with VFR conditions prevailing this afternoon
and evening. We can't really rule out a passing shower today,
especially along the coast and over the mountains, but most TAF
sites are unlikely to see much. The front approaches the coast
late tonight and Sunday morning, and this should keep conditions
mixed enough to prevent fog formation tonight. However, the
airmass is quite moist, so any clearing could quickly result in
fog over inland valleys. -Wright

&&

.PREV DISCUSSION... /Issued 929 AM PST Sat Nov 11 2017/

UPDATE...A weak ridge built into the area overnight, which has
cleared up showers and supported formation of valley fog/low
clouds. The ridge is moving quickly; the axis is mostly east of
the CWA, and light showers in have returned to the coast. Today
will be a quiet weather day with highs in the mid 50s west of the
Cascades and mid 40s east of the Cascades. We'll see clearing this
afternoon, then by late afternoon/evening mid to high clouds from
the next system will start rolling in, bringing rain as early
this evening along the coat, and tonight in west side valleys. The
wettest periods still look to be Sunday night into Monday for
most areas. Winds will be a concern as early as Sunday evening and
winds Sunday into Monday will be given a close look before the
afternoon forecast package is sent out. Otherwise, made some
morning updates to adjust wind direction and speed for today, but
in general the current forecast is on track. See previous
discussion for further information. -MSC

PREV DISCUSSION... /Issued 538 AM PST Sat Nov 11 2017/

SHORT TERM...Today (11/11) through Tue (11/14)...The pattern for
the next week will remain seasonably cool, and frequently wet and
breezy to windy. Model agreement remains very good into Wednesday.
The focus is on a few frontal systems...Sunday night into Monday,
Monday evening ,and especially late Tuesday through Wednesday
night.

There will be a relative break in the weather today through Sunday
with the exception of a saturated onshore flow continuing a few
light coastal showers today that will become numerous on Sunday.

Inland, morning low and mid level clouds are thickest from the
Cascades westward. These clouds will dissipate at least partially
into the afternoon as a fast moving ridge with drier air aloft
briefly moves across the area.

Low and mid level clouds will be on the increase again tonight in
advance of a cold front. Rainfall will increase in coverage and
intensity at the coast early Sunday evening but the bulk of
coastal precipitation will be accompanied by gusty southerly
winds late Sunday night into Monday morning. The snow level Sunday
night will be around 6500 feet with precipitation spreading to
the Cascades by Monday morning. Winds will also be gusty inland
with the potential for advisory strength gusts up to 50 mph late
Sunday evening through Monday afternoon over the higher terrain,
southern Shasta Valley, and near Summer Lake in Lake County.

A surface trough associated with the parent upper low will follow
on Monday night with light to locally moderate precipitation and a
snow level falling from 5500 feet to 4000 feet.

Tuesday looks to be mostly dry inland from the coast, but a wet
frontal system will likely bring rain to the coast by late
afternoon and heavy rain at the coast with strong southerly winds
during Tuesday night. -DW

LONG TERM...Wed (11/15) through Fri (11/17)...The front still
looks to be a good soaker for our area through Wednesday, but
especially the normally wetter locations like the south coast and
coast range which could easily see 2 to 4 inches of rain. Models
are showing snow levels a little lower than they had been, but
they are still expected to stay just above Siskiyou Summit during
the heaviest precipitation, so snow impacts may be minimal. That
said, it is close, so those planning to travel along I-5 mid next
week should pay attention to updated forecasts as we get closer.
There will likely be snow impacts (possibly significant) over the
Cascades on Wednesday. The other potentially significant impact
with this front will be the strong south winds in the usual windy
locations like the Shasta Valley, East Side, and possibly portions
of the coast. We may even see breezy winds into the Rogue Valley.

The front moves east of the area early on Thursday morning
leaving us with residual showers and snow showers from a surface
trough as the axis of the upper level low swings through. Snow
levels are expected to be around 3500 feet.

Model differences increase beginning Thursday with a wide range of
solutions into the weekend. There may be a break between systems
on Friday but the overall pattern is likely to remain active.
-Wright/DW

MARINE...Updated 915 AM PST Saturday 11 November 2017...Low
pressure will move through the waters west of Coos Bay this
afternoon and evening with increasing south wind and some gusts
around 30 kts. Meanwhile moderate west swell will combine with
wind chop to maintain steep hazardous seas over all areas through
tonight. Winds and seas will increase Sunday into Sunday night
ahead of a strong front bringing very steep seas and areas of gale
force winds. The front moves onshore late Sunday night. More
fronts will follow Monday through Wednesday morning, then
conditions relax Wednesday afternoon into Thursday. MTS

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

Pacific Coastal Waters...Hazardous Seas Warning from 10 AM Sunday
     to 10 PM PST Monday for PZZ350-356-370-376.
     Small Craft Advisory for hazardous seas until 10 AM PST Sunday
     for PZZ350-356-370-376.