Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 251239

Area Forecast Discussion
National Weather Service Medford OR
539 AM PDT WED MAY 25 2016

.AVIATION...For The 25/12Z TAF Cycle...Areas of stratus with MVFR
cigs is present mainly over the coast and Umpqua basin this
morning, and this will likely continue much of the day. Elsewhere,
conditions generally remain VFR and will through the TAF period.


.PREV DISCUSSION... /Issued 404 AM PDT WED MAY 25 2016/

DISCUSSION...There is little change in the expected weather
during the short term and increased confidence in the long term
portion this weekend into early next week.

The GFS and ECMWF solutions have trended toward each other
regarding the Memorial Day weekend and the forecast highs have
been raised by a few degrees in accordance with the updated model
data. It looks to be mostly though not entirely rain-free with
high temperatures near normal on Saturday trending warmer at least
into Tuesday. There will be an even wider than normal diurnal
range of temperatures with cool morning lows in the 40s in most
west side valleys and cold morning lows in the 30s at ridges and
across the east side.

First, a few showers are lingering in Lake, Siskiyou, and Modoc
Counties early this morning as a shortwave moves southeast across
southeast Oregon. Shower activity looks to increase slightly into
the early afternoon with a majority of the showers and also a
slight chance of thunderstorms over the Warner Mountains of Lake
and Modoc Counties. The probability of showers will diminish late
today into tonight as low pressure moves into the Great Basin and
a shortwave ridge builds into the west coast. This will strengthen
a thermal trough at the coast with weak easterly winds expected to
result in reduced cloud cover in southern Curry County Wednesday

Our weather from Thursday through Sunday will be affected by a
series of very weak disturbances moving through the southern edge
of a longwave trough that will persist over western Canada. This
will produce an onshore flow at the coast with a few light day-
time showers and patches of late night and morning drizzle at the
coast north of Cape Blanco and into Douglas County. The
probability of light showers will be higher north of our area. It
warrants emphasis that any showers will not amount to much...a
likely only a trace to a few hundredths of an inch in all. More
notable is the expectation of Coastal and Douglas County night and
early morning low clouds. Otherwise...skies look to be mostly
sunny to sunny. Temperatures will remain very slightly below
normal through Friday then reach normal on Saturday and continue a
warming trend early next week.

There does remain some uncertainty regarding the possibility of
weak instability developing east of the Cascades on Sunday
afternoon and evening as a shortwave trough moves east across
northern Oregon. Once again, the best chance for a light shower
will be across the northern fringe of our area.

The models now show a strengthening ridge and thermal trough on
Memorial Day into Tuesday. There is moderate uncertainty in the
forecast for Tuesday and Wednesday. Both days still are likely to
be warmer than normal but the timing and track of the west coast
ridge and an approaching trough over the eastern Pacific are in
question. This could introduce instability into the air mass with
a possibility of showers and thunderstorms as early as Tuesday
afternoon...though possibly holding off until Wednesday afternoon
or even day 8/Thursday afternoon.

MARINE...Updated 230 AM PDT Wed 25 May...High pressure well
offshore and lower pressures over land will remain in place and
continue to drive north winds and mainly wind driven seas over the
waters through at least the next week. Winds will ramp up today
and peak on Thursday. Then, winds remain north but weaken a bit
Friday into the weekend as weak fronts move by to the north. Winds
are expected to increase substantially and may reach gale force
early next week as a strong thermal trough develops. Winds will be
strongest and seas highest over the southern waters throughout the
forecast period. -Wright


.MFR Watches/Warnings/Advisories...


Pacific Coastal Waters...Hazardous Seas Warning from 5 PM this
     afternoon to 11 PM PDT Friday for PZZ356-376.
     Small Craft Advisory for hazardous seas from 11 AM this morning
     to 11 PM PDT Friday for PZZ350-356-370-376.

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