Storm Watch 6, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
252 PM PDT Tue Apr 4 2017

.SHORT TERM...High clouds continue to move into the area, keeping
temperatures slightly below normal for this time of year, despite
the long wave ridge situated over the PacNW. Radar returns have
shown virga over the area all day... no observations have reported
rainfall reaching the surface. The area will soon move into a
more progressive pattern as the ridge moves eastward. A frontal
system will move toward the coast tomorrow... bringing the chance
of precipitation over the Coastal Range and west... spreading
towards the Cascades and Siskiyous in the afternoon and evening.

Precipitation will move farther inland Thursday, as the front moves
inland. Maintained around a 50 percent chance of precipitation in
the Rogue Valley, as southeast winds should prevent most rain from
reaching the ground in the valley. Gusty winds will develop over
high elevations on the east side Thursday... and though they will
diminish slightly late Thursday night... this will be short lived,
as the next system will be much stronger.

A stronger low pressure system will develop Thursday night into
Friday, likely bringing rain to our entire area, with several inches
expected along the coast, Coastal Range, and Siskiyous
Friday through Saturday. Expect strong winds over the marine area,
coast, Shasta Valley, east side, and some west side valleys. As this
system moves near the coast, winds will increase over the Cascades,
East Side, and Shasta Valley, coast, and possibly some west side
valleys. Peak wind gusts should occur Friday afternoon.

Winds will diminish Saturday as the main surface low begins to fill
and move north. Snow levels will drop behind the low... to
4000 feet or below. Another system will move in from the
southwest Saturday, bringing more precipitation. -MSC

.LONG TERM...Saturday through Tuesday...The pattern will continue
to remain fairly active through the period. Another storm will
impact the area on Saturday. This one will not be as strong in
terms of winds, but there will be ample moisture with moderate to
heavy rain and mountains snow for the coast and coast Range. Also
moderate to heavy snow is possible for the Cascades and Siskiyous
with snow levels around 3500 feet. We'll catch a relative break on
Sunday with shortwave ridging, then another front will reach the
coast late Sunday afternoon, then move inland Sunday night. Moist
onshore flow with showers mainly along and west of the Cascades
are expected Monday, then we could catch another break in the
weather Monday night into Tuesday. Note, the ECMWF and GFS are in
pretty good agreement with the overall pattern through this
forecast period. -Petrucelli

&&

.AVIATION...03/18Z TAF CYCLE...VFR cigs will continue through the
TAF period. The one concern is the chance for low level wind shear
at the coast, including North Bend late this evening into Wednesday
morning and early Wednesday morning in the Umpqua Basin including
Roseburg and these are reflected in the TAF for these locations.
-Petrucelli

&&

.MARINE...Updated 215 PM PDT Tuesday 4 April 2017...A cold front
will move into the waters tonight...then stall over the area as weak
waves develop on the frontal boundary and propagate north.  The
front will move inland Thursday. Small craft seas will affec all of
the waters...but small craft winds will remain over the outer waters
except near Cape Blanco.  A deep low will move north just west of
the coastal waters Friday. This storm may bring storm force winds to
the outer waters and gale force winds to the inner waters. A weaker
storm will move from the southwest Friday night into Saturday...then
high pressure will build in Saturday afternoon and evening. Yet
another front will move onshore Sunday night. -JRS

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Watch from late Thursday night through Friday
     afternoon for ORZ021-022.
     Wind Advisory from 5 AM Thursday to 11 AM PDT Friday for
     ORZ030-031.
     High Wind Watch from Friday morning through Friday evening for
     ORZ030-031.

CA...Wind Advisory from 5 AM Thursday to 11 AM PDT Friday for CAZ085.
     High Wind Watch from Friday morning through Friday evening for
     CAZ085.
     High Wind Watch from late Thursday night through Friday
     afternoon for CAZ081.

Pacific Coastal Waters...High Wind Watch from late Thursday night through Friday
     afternoon for PZZ350.
     Gale Watch from Thursday evening through Friday evening for
     PZZ350-356.
     Small Craft Advisory until 11 PM PDT Thursday for
     PZZ350-356-370-376.
     Small Craft Advisory for hazardous seas from 5 AM Wednesday to
     11 PM PDT Thursday for PZZ350-356-370-376.
     Storm Watch from Thursday evening through Friday evening for
     PZZ370-376.

MSC/MAP/JRS