Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 251600
AFDMFR

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

.Discussion...A minor update to precipitation chances was made
this morning to reduce rainfall chances over the Umpqua Basin this
afternoon. Morning drizzle and light rain was observed this
morning at the coast north of Cape Blanco and in the Umpqua Basin,
and this will be a feature that persists the next few mornings
under the influence of onshore flow, marine clouds, and weak
shortwaves aloft. Drier northwest flow will prevent showers from
forming over much of the area today, but there is a slight chance
of showers and thunderstorms mainly over southern Lake and Modoc
counties. High temperatures will be near to just below normal.

Tonight, the aforementioned onshore flow is expected again,
bringing clouds to much of the west side, but clear skies are
expected at the coast in Curry County due to offshore flow there.

Cool conditions will continue through Thursday before a warmup
just in time for Memorial Day weekend. We`ll be taking a look at
forecast low temperatures for the Klamath Falls area because
near-freezing temperatures are a good bet there, and we may need
some freeze products to bring attention to potential garden and
agricultural impacts.

Please see the previous discussion below for more details on the
mostly warm and dry weekend forecast.

&&

.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. -Wright

&&

.Marine...Updated 230 AM PDT Wed 25 May...High pressure well
offshore and lower pressures over land will 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/BPN

&&

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
night.

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.

&&

.MFR Watches/Warnings/Advisories...
OR...None.

CA...None.

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 until 11 PM PDT Friday
     for PZZ350-356-370-376.

$$

NSK/DW/TRW


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