Area Forecast Discussion
Issued by NWS Medford, OR

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388
FXUS66 KMFR 310320
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
820 PM PDT MON MAY 30 2016

.DISCUSSION...No updates needed this evening. An upper ridge is
centered right over us this evening with a low level thermal
trough underneath. The axis of both features is roughly just west
of the Cascade crest, and this is where the warmest conditions
reside. The flow is slightly onshore at the coast, and the models
are starting to hint at some stratus developing there tonight.
However, we`ll just keep an eye on that, because with north winds
and a temp/dewpoint spread of 7F at North Bend, stratus is not
imminent. Elsewhere, skies remain mostly clear through the night
as the ridge/thermal trough very gradually shifts east. -Wright

&&

.AVIATION...For the 31/00Z TAF cycle...VFR conditions will continue
through Tuesday evening. Gusty, moderate to strong north winds along
the coast this evening will diminish overnight. These winds will
then increase again Tuesday afternoon but will not be quite as
strong as they were today. -DW

&&

.MARINE...Updated 520 PM PDT Mon 30 May 2016...Offshore high
pressure and a thermal trough along the coast will continue to
produce gusty north winds this week with short period wind waves and
fresh swell continuing to dominate the waters. Winds will be
strongest in the outer waters south of Cape Blanco. Winds will reach
a peak this evening then trend weaker into Thursday as the high
weakens and moves closer to shore. Gales in the southern outer
waters this evening will taper to advisory strength late tonight
through Tuesday evening and may remain at advisory strength into
Wednesday evening. Wind speeds will be at a minimum on Thursday but
the decrease will not last long. North winds are likely to increase
again Friday into the weekend. -DW

&&

.PREV DISCUSSION... /Issued 216 PM PDT MON MAY 30 2016/

DISCUSSION...

Short Term...Tonight through Thursday Night...Upper level
ridging and the thermal are combining to produce clear skies and
very warm temperatures, which should persist through nearly the
entire short term. THe warmest days of the short term will be
tomorrow and Wednesday, with high temperatures of 5 to 10 degrees
above normal along the north coast and up to 20 degrees above
normal along the south coast and for all areas inland. Newer model
runs have pushed up temperatures slightly in some areas, and this
has brought triple digit forecast highs to some localized areas in
the Klamath/Salmon valleys of western Siskiyou County and in the
Illinois valley in Josephine County. Other areas in the West Side
valleys could get really close to that mark as well. The thermal
trough will shift inland Wednesday, and while this will bring
cooler temperatures to the immediate coastline, there will be
little change otherwise, with the West Side on average slightly
cooler and the East Side slightly warmer. Thursday will be a near
clone of Wednesday, in terms of temperature, but onshore winds
later in the day should start a slight, although brief, cooling
trend heading into the extended.

Despite the warm temperatures and mostly clear skies, there is
the possibility for some convection to develop Wednesday
afternoon. Model solutions have backed off on the areal coverage
of precipitation, which is not unexpected given the lack of a
lifting mechanism over the past several runs. However, all of the
model suites are producing some very small areas of convection
Wednesday in the Mt Shasta to Medicine Lake region, probably more
due to terrain influences than any shortwave or other lifting
feature. Therefore, confidence remains low, but have kept the
slight chance of showers and/or thunder in the forecast for the
afternoon and evening Wednesday, with some modification of areal
coverage to more coincide with the latest model guidance. Thursday
should remain dry, aside from some light drizzle in the morning
along the coast north of Cape Blanco, as onshore flow encounters
the coastline. -BPN

Long Term...Friday through Monday Night...Friday into the
weekend, models continue to show agreement that the ridge will
strengthen over the area while a closed low to the south gradually
moves inland into the central California coast. This pattern is
expected to bring warming temperatures to the area Friday and
Saturday. Peak temperatures are expected on Saturday with highs in
the 90s to near 100 in western inland valleys and in the upper 80s
to near 90 for valleys east of the Cascades.

For Sunday, the GEFS, GFS and ECMWF have trended further north with
the track of the closed low, bringing it into central to south
central California. This low is forecast to send southerly mid level
moisture into the area as well as shortwave activity. Although
temperatures are expected to be slightly lower on Sunday, compared
to Saturday, daytime heating will provide plenty of instability.
Have expanded the chance for thunderstorms over inland areas on
Sunday. Moisture, instability and shortwave activity continue
overnight Sunday into Monday morning so have kept a slight chance
for thunderstorms in during this period. On Monday, models show the
low gradually moving inland to the east-northeast into Nevada.
Continued moisture around this low will bring additional chances for
showers and thunderstorms to the area. Of note, the track of this
low remains the main factor in determining which areas will see the
best chance for thunderstorms and model ensemble solutions continue
to show variability with the track as it moves inland. /CC

Fire Weather...Next week will be warm and dry with a rapid
warming from Tuesday onward. Confidence is high that the valleys W
of the Cascades will see high temperatures in the 95 to 100 degree
range as the thermal trough shifts inland and remains W of the
Cascades on Tuesday and Wednesday. Expect minimum RH for western
valleys to be in the mid teens with fair to poor recovery Tuesday
night and Wednesday night. The thermal trough is expected to shift
east of the Cascades Wednesday but onshore push will be confined
mainly to Douglas County of Oregon.

Around Wednesday we will have to contend with thunderstorm chances
as southerly flow aloft strengthens and allows more moisture and
instability to spread north. Right now we see only the higher
terrain such as the Cascades/Siskiyous, Marble Mountains, the
mountains of the Fremont-Winema Forest being the most likely area
to see lightning strikes. Confidence is not high on how much rain
these storms will produce. By Friday instability appears to be
shunted to central California and we have removed thunderstorm
chance from the forecast. Hot temperatures inland will continue into
the end of the week. /FB

&&

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

CA...None.

Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT Tuesday
     for PZZ356-376.
     Small Craft Advisory for hazardous seas until 11 PM PDT Tuesday
     for PZZ350-356-370-376.
     Small Craft Advisory until 11 PM PDT this evening for
     PZZ350-370.
     Gale Warning until 11 PM PDT this evening for PZZ376.
     Hazardous Seas Warning until 11 PM PDT this evening for PZZ376.

$$



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