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FXUS66 KMFR 260607
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1107 PM PDT Tue Apr 25 2017

The Marine and Aviation sections have been updated...

.UPDATE...
Updates have been sent for the overnight and Wednesday forecast.
These updates have been to refine the QPF forecast, snow levels,
and snow amounts. BTL

&&

.DISCUSSION...
A steady plume of moisture continues to extend from a tropical
storm in the Western Pacific Ocean all the way into the Pacific
Northwest. Rain has been fairly light across the forecast area,
thus far, today, though Brookings and Red Mound are indicating 24
hour totals in the 1-2 inch range.

Rain is expected to pick up substantially overnight into Wednesday
morning as the triple point of the incoming low pressure system
approaches and moves through. Short range models are really
keying in on the precipitation maximum being in the Cascades near
Mount McLoughlin to the southern portion of Crater Lake National
Park with this frontal system, with over 2 inches of water
expected there. Due to the higher precipitation rates expected
late tonight through Wednesday morning I decided to lower snow
levels a few hundred feet. They still should remain above 5500
feet, which is the base elevation for issuing advisory and warning
products in the Cascades. However, above 6500 feet another 1-2
feet of snow is expected to fall, especially above 7000 feet. For
lower elevations rain is expected, and the Rogue Valley from
Medford to Ashland is expected to get 0.25 to 0.50 inches of rain
in the next 24 hours. Northwest flow in the Ashland area Wednesday
afternoon and evening is likely to make it a soggy afternoon and
evening for the south end of the valley.

Suffice it to say that spring will kick into a warmer gear
beginning Thursday into next week. There are now indications in
the guidance that the Medford area will probably reach or surpass
80 degrees for the first time this season around the middle of
next week. BTL

&&

.AVIATION...26/06Z TAF CYCLE...A cold front will move toward the
area tonight. Widespread IFR ceilings and visibilities will impact
coastal areas tonight into Wednesday morning with moderate rain and
local LIFR. Conditions there will begin to improve after 14z
Wednesday after the cold frontal passage, but a mix IFR and MVFR is
still expected through Wednesday afternoon. The coastal mountains
will remain obscured through late afternoon.

Inland, conditions will deteriorate to mostly MVFR with occasional
rain and higher terrain obscured overnight into Wednesday. Areas of
VFR are expected early in the night ahead of the front, and IFR is
possible with the front late tonight into Wednesday morning.
Precipitation will become more showery Wednesday afternoon with a
mix of MVFR and VFR. Gusty west to northwest winds will develop east
of the Cascades Wednesday afternoon. Wind gusts to 30 kt are
expected at KLMT, which will likely lead to some bumpiness on
takeoffs and approaches. -Spilde

&&

.MARINE...Updated 835 PM PDT Tuesday, 25 April 2017...
Steep southwest seas will continue tonight into early Wednesday.
Southwest winds will turn west to northwest around sunrise as a cold
front moves through. Offshore high pressure is expected to build in
from the southwest on Thursday and then persist through the weekend.
Northerlies are then expected to become gusty Friday and Saturday
with the strongest winds and steepest seas likely to be south of
Gold Beach. BTL

&&

.PREV DISCUSSION... /Issued 508 PM PDT Tue Apr 25 2017/

DISCUSSION...

Short Term...Tonight through Thursday...Onshore flow earlier
today had deeper moisture than expected thus portions of the East
Side have already seen rain. Precipitation will increase over our
entire forecast area tonight. Expect overnight lows 5 to 10
degrees above normal given precip and cloud cover. The heaviest
precipitation will be late tonight into tomorrow morning, ahead of
a cold front. Areas along the coast can expect 1 to 1.5 inches of
precipitation over the next 24 hours... with highest amounts
along the Curry County coast and mountains. Expect around a third
of an inch in the Rogue Valley... with one half to one inch in the
Umpqua Valley. Gusty winds in strong westerly flow will impact
the East Side tomorrow afternoon... with sustained winds around 25
mph and occasional gusts of 40 mph in Paisley and Christmas
Valley.

Snow levels are above 7000 feet now... and will generally stay above
6500 feet tomorrow. Snow levels will drop to 3500 to 4500 feet late
Wednesday night behind the cold front, and overnight lows Wednesday
into Thursday will be below freezing over most of the East Side...
and between 30 and 40 degrees in west side valleys. Since the
heaviest precipitation will be ahead of the cold front, snow impacts
are not expected. Some showers will continue into Thursday in
continued moist onshore flow, but accumulations likely won't be more
than a few hundredths of an inch. -MSC

Long Term...Friday through Tuesday...A broad, high amplitude ridge
will build in over the West Coast by the weekend and is expected to
stay in place through the first half of next week. This should keep
the area dry and warm for the remainder of the forecast period. The
models are depicting a few systems riding up and over the ridge, but
these should be deflected well to our north, and aside from some
periods of increased cloudiness, there will be little to mark their
passage. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 11 AM to 8 PM PDT Wednesday for ORZ030-031.

CA...Wind Advisory from 11 AM to 8 PM PDT Wednesday for CAZ085.

Pacific Coastal Waters...
- Small Craft Advisory until 5 AM PDT Wednesday for PZZ350-356-370-
376.


$$

BTL/MSC/BPN
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