Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 231615
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
910 AM PDT Thu Mar 23 2017

Updated Aviation section...

.UPDATE...No significant changes are necessary this morning, as
conditions across the area are coming along well in regards to he
forecast. The exception is fog, which has developed in some of
the valleys of the West Side and along the coast. Have updated to
add fog, but have left the remainder of the inherited forecast as
it was. Major forecast efforts today will focus on the upcoming
system for this evening and tonight, and the next system due in
late this weekend. For more information, see the previous
discussion below. -BPN

&&

.AVIATION...23/12Z TAF CYCLE...Updated 9am PDT...
IFR to MVFR low clouds and patchy IFR to LIFR fog has formed since
sunrise across many valley areas this morning. Expect this to
dissipate over the course of the morning leading to VFR as a frontal
system approaches. Southerly winds will increase ahead of the cold
front today, so expect increased turbulence, especially over and
near high terrain and east of the Cascades. Winds at the coast will
also become gusty late this afternoon. Ceilings will gradually lower
this evening, from west to east across the forecast area, and expect
mountain obscuration to follow. BTL/SK

&&

.MARINE...Updated 300 AM PDT Thursday 23 March 2017...A strong front
offshore will move toward the coastal waters late this morning.
Widespread gales can be expected early this afternoon through this
evening, especially beyond 10 NM from shore, but also closer to
shore near Cape Blanco. A few gusts to storm force are possible.
Seas will become steep to very steep during this time period and
persist through tonight. Winds and seas will decrease Friday into
Saturday...but seas likely remain quite steep. Another strong front
is due to arrive on Sunday. -Spilde/SK

&&

.PREV DISCUSSION... /Issued 604 AM PDT Thu Mar 23 2017/

DISCUSSION...A frontal boundary will bring gusty winds to our
forecast area this afternoon. Wind advisory continue for the
Shasta Valley and part of east side of the Cascades along with the
Warner Mountains of Modoc County this afternoon through tonight.

Wind forecast at the coast is a little trickier. We generally look
at OTH to ACV pressure gradient and the character of the Low
Pressure as well as how the low level winds align against the
coastal range. In this case, while winds at H925 and H850 HPA are
in the 50-60kt range, the gradient is only 6.0 and the Low is
farther offshore and not deepening. Also H925 wind direction is
more out of the South and Southeast and does not have the SW
direction that forces mass onto the coastal range. I feel that the
coastal headlands and the higher terrain in the coastal range
could see the very strong winds and the High Wind Watch was
canceled. The coast will still be very windy but the strongest
winds will be mainly at the headlands.

The front is expected to spread precipitation into SW Oregon this
afternoon with snow levels around 5000 feet. The front is
expected to move inland tonight and somewhat stalls over the
Cascades not exiting until Friday. Crater Lake, Mt Ashland and Mt
Shasta could see around a foot of new snow by Friday morning.

Precipitation is expected to taper off to light showers by Friday
evening. Scattered showers will continue into Saturday except for
the coast and the Umpqua Basin where precipitation is expected to
be steadier. Saturday night could be dry but both the GFS and the
ECMWF bring another front inland on Sunday. /FB

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 11 PM this evening to 11 AM PDT
     Friday for ORZ030.
     Winter Weather Advisory from 11 PM this evening to 11 AM PDT
     Friday for ORZ027.
     Wind Advisory from 2 AM to 5 PM PDT Friday for ORZ031.

CA...Wind Advisory from 2 AM to 5 PM PDT Friday for CAZ081.
     Wind Advisory from 2 AM to 5 PM PDT Friday for CAZ085.
     Winter Weather Advisory from 11 PM this evening to 11 AM PDT
     Friday for CAZ082-083.
     Winter Weather Advisory from 11 PM this evening to 11 AM PDT
     Friday for CAZ080.

Pacific Coastal Waters...
- Gale Warning until 4 AM PDT Friday for PZZ350-356-370-376.
- Hazardous Seas Warning until 11 AM PDT Friday for PZZ350-356-370-
  376.
- Small Craft Advisory for hazardous seas from 11 AM to 5 PM PDT
  Friday for PZZ350-370.
- Small Craft Advisory for hazardous seas until 11 AM PDT this
  morning for PZZ370-376.

$$

BPN/BTL/FB/NSK


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