Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 261148
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
448 AM PDT Sun Mar 26 2017

.Updated Aviation Discussion.

.DISCUSSION...Yet another system brings snow to the already
healthy snow pack in the higher elevations. Although the 700 mb
winds are slightly more west from the south to southwest direction
normally desired, the gradient briefly peaks around 7 mb from RDD
to MFR and this should bring winds to advisory levels in the
southern Shasta valley today, and the winds are already gusting to
near 30 mph at the Weed airport at this time. With the gradient at
the coast not tightening as much as we look for and a slightly
offshore component to the winds am not expecting winds to reach
warning levels there. A cold air mass moves in behind the front
this afternoon with 500 mb temperatures moving over the region,
lowering to near -28 C this evening into Monday morning. East of
the Cascades the edge of this cold air mass combines with the warm
flow from the south, bringing LI`s down to near -2 in Lake and
Klamath counties and possible thunderstorms. The strong lapse
rates keep healthy shower activity with snow levels down to the
Cascade passes and over Siskiyou summit. With warmer road
temperatures with the higher sun angles however, snow should melt
quickly and travel impacts should not be long lasting. With the
colder air mass moving in towards Monday morning the impacts may
last a little longer. The cold air mass aloft will shift east
Monday afternoon as an upper level ridge builds into the region.

Tuesday will see a break in the action before the upper ridge
shifts east ahead of the next system that moves in Tuesday night.
the axis of this vigorous jet is well north of the area, but moves
south with the left exit region of the jet over the forecast area
Wednesday evening. Sven


&&

.AVIATION...26/12Z TAF CYCLE...A cold front will arrive at the coast
early this morning and weaken as it spreads inland through the day.
Ahead of this front, a stronger SW winds aloft could lead to low
level wind shear at North Bend early this morning, then mid morning
at Roseburg and Medford. Low level wind shear should not be a
concern by this afternoon and kept it out of the TAF, but will need
to be reevaluated. The front will also bring increased coverage of
MVFR for areas west of the Cascades with local IFR over the coastal
range. Snow levels will be around 5000 to 5500 feet MSL.
-Petrucelli

&&

.MARINE...Updated 230 AM PDT Sunday 26 March 2017...South winds are
already increasing and are approaching small craft ahead of the next
front that is still west of the waters. South winds will ramp up
further to Gales in the next few hours with gales expected to last
into the afternoon. Steep seas are also expected. The models are in
pretty good agreement pushing the front onshore this evening at
which point winds will decrease and become southwest. However seas
will remain steep through this evening. Seas will decrease tonight
into early Monday morning, then a combination of a longer period and
shorter period west swell is due to move in Monday afternoon
resulting in combined seas between 10-13 feet. Steep seas could
linger through at least Wednesday night. -Petrucelli


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 11 AM PDT Monday for ORZ027-028.

CA...Wind Advisory from noon today to 8 PM PDT this evening for
     CAZ081.

Pacific Coastal Waters...Small Craft Advisory until 6 AM PDT early
this morning for      PZZ350-356-370-376.      Gale Warning from 6
AM this morning to 5 PM PDT this afternoon      for PZZ350-356-370-
376.      Hazardous Seas Warning from 6 AM this morning to 5 PM PDT
this      afternoon for PZZ350-356-370-376.

$$

SBN/SBN/SBN



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