Small Craft Advisory 106, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
312 PM PST Fri Nov 24 2017

.SHORT TERM...Today through Monday night...
It's been a seasonably cool day across the area today with some
low clouds trapped in the west side valleys and high clouds
streaming in from the southwest. These high clouds are the
leading edge of a warm front that will move through the forecast
area from south to north during the next 24 hours.

We expect all areas will remain precipitation free through about
sunrise Saturday morning. If high clouds are patchy or thin
tonight, we'll see a return of low clouds and patchy fog for some
of the valleys west of the Cascades tonight, but expect this will
be mitigated by the cloud cover coming in and an increasing east
to west pressure gradient.

Saturday south and southeast winds will become breezy in the
Shasta Valley, southern portion of the Rogue Valley, mountains,
and east side. This will result in better vertical mixing and
some downslope warming Saturday, which will persist through
Sunday morning. Please see the wind advisories and high wind
warning as well as the detailed hazards link for further
information on the wind.

The warm front on Saturday will bring light precipitation amounts
to the area, but, as is typical with warm fronts, it's likely to
be more widespread with less upslope enhancement and downslope
rain shadowing as compared to cold fronts. Snow levels initially
near 7000 feet are expected to rise to 8500-9000 feet.

Saturday night into Sunday the cold front will move into the area
with stronger southerly winds and increasing precipitation. Snow
levels will begin to lower, with most of the precipitation
occuring with snow levels 7kft or higher.

Model guidance has trended drier for the Sunday night through Monday
time frame, when snow levels fall from 6500 to 3500 feet. Thus,
while the upper slopes of Mount Shasta are likely to receive 20-30
inches of snow above 7.5kft from this storm, areas below 6500
feet are expect to get less than 6 inches. Rainfall amounts in the
Mount Shasta area are expected to be 1-2 inches, and Curry County
should be 1.5-2.5 inches from Saturday through Monday morning.
BTL

.LONG TERM...Tue (11/28) through Fri (12/01)...
The 21/12Z EC and GFS start off the extended in good agreement.
They both show a long wave ridge over the Pacific Northwest with
the ridge axis just to the east of the Medford CWA.

Previous runs showed this ridge remaining over the area into
Wednesday, but the new runs are going with a more progressive
pattern, bringing another long wave trough onshore Tuesday. The
associated front, which will be fairly weak in terms of wind and
precipitation, will move onshore Tuesday. The upper level support
for this front will move on out and an upstream long wave ridge will
then build into the area. Therefore, the front will pretty much
dissipate over the area, and precipitation will end Tuesday night
into Wednesday.

In response to the building ridge, the low level flow will turn
offshore Wednesday night, and this will dry out the area. The ridge
axis will break to the east of the area Thursday night, but the
upstream trough will be slow to come in, so there won't be any
fronts moving onshore until Friday afternoon at the earliest, more
likely Saturday. Will go with a dry forecast Wednesday afternoon
into Thursday night, then bring in some slight chance to chance POPs
Friday, mostly along the coast.

&&

.AVIATION...25/00Z TAF CYCLE...VFR will prevail through this
evening. Patchy low clouds and fog will produce LIFR cigs/vsbys in
portions of the coastal valleys, Umpqua Valley, Illinois, Applegate,
Rogue, and lower Klamath Valleys between around 06Z tonight and 18Z
Saturday morning. The lower conditions will clear to VFR by 18Z
Saturday. Low level southerly winds will increase on Saturday ahead
of a strong front, and build to a peak Saturday night.

&&

.MARINE...Updated 250 PM PST Friday 24 Nov 2017...Weak high
pressure will bring diminishing seas through this evening. A strong
front will bring strengthening south winds Saturday, with gales and
very steep seas developing by the end of Saturday afternoon and
continuing into early Sunday morning. Seas will remain high and
steep to very steep on Sunday. High and steep seas will continue
into early next week. On Tuesday night into Wednesday, a high long
period west swell is expected to build into the waters. Seas on
Wednesday may build into the 15-20 foot range. /DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 2 PM Saturday to 4 AM PST Sunday for
     ORZ030-031.
     Wind Advisory from 2 PM Saturday to 4 AM PST Sunday for
     ORZ029>031.
     High Wind Watch from late Saturday night through Sunday
     afternoon for ORZ030-031.
     Wind Advisory from 2 PM Saturday to 4 AM PST Sunday for ORZ026.

CA...High Wind Warning from 2 PM Saturday to 4 AM PST Sunday for
     CAZ085.
     Wind Advisory from 2 PM Saturday to 4 AM PST Sunday for
     CAZ084-085.
     High Wind Watch from late Saturday night through Sunday
     afternoon for CAZ085.
     High Wind Warning from 2 PM Saturday to 4 AM PST Sunday for
     CAZ081.
     Wind Advisory from 2 PM Saturday to 4 AM PST Sunday for CAZ081.
     High Wind Watch from late Saturday night through Sunday
     afternoon for CAZ081.

Pacific Coastal Waters...
- Hazardous Seas Watch from late Saturday night through Sunday morning
  for PZZ350-356-370-376.
- Gale Warning from 4 PM Saturday to 4 AM PST Sunday for
  PZZ350-356-370-376.
- Hazardous Seas Warning from 4 PM Saturday to 4 AM PST Sunday
  for PZZ350-356.
- Small Craft Advisory from 10 AM to 4 PM PST Saturday for
  PZZ370-376.

BTL/15/DW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1107 AM PST FRI NOV 24 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 AM     HEAVY RAIN       6 E GOLD BEACH          42.42N 124.31W
11/24/2017  M1.59 INCH       CURRY              OR   TRAINED SPOTTER

            THE DURATION OF THE HEAVY RAIN EVENT WAS 24
            HOURS.

&&

BPN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1109 AM PST FRI NOV 24 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 AM     HEAVY RAIN       BROOKINGS               42.06N 124.29W
11/24/2017  M1.06 INCH       CURRY              OR   TRAINED SPOTTER

            THE DURATION OF THE HEAVY RAIN EVENT WAS 24
            HOURS.

&&

BPN