Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 290317
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
817 PM PDT TUE JUN 28 2016

.UPDATE...NO major changes were necessary this evening, as the
forecast appears to be mostly on track. However, some of the sky
conditions were changed to bring them more into line with current
observations, mainly in regards to the lack of cloud cover across
much of the inland areas. Otherwise, clear and dry remain the
rule, aside from marine layer clouds along the coats north of cape
blanco. -BPN

&&

.AVIATION...


&&

.MARINE...


&&

.PREV DISCUSSION... /Issued 504 PM PDT TUE JUN 28 2016/

DISCUSSION...Temperatures are generally within a few degrees of
yesterday`s temperatures 24 hours ago as a persistent weather
pattern remains over the forecast area. Dry southwest flow in the
upper levels will gradually shift towards more of a westerly flow
toward the weekend, pushing temperatures slightly lower and
preventing any significant chances for precipitation.

The marine layer will deepen slightly over the next several days
as an upper trough moves closer from the west and temperatures
aloft cool some. The approaching upper trough will push marine
stratus clouds back into the coast and coastal valleys this
evening, while offshore northeasterly flow keeps most areas south
of Cape Blanco clear. Clouds should reach close to Roseburg
tonight, with guidance mixed on that forecast point.

Tomorrow and Thursday will feature similar weather, but Thursday may
feature enough moisture and instability ahead of a weak upper trough
to bring a few lightning strikes to mainly the Winter Ridge area in
Lake/Klamath Counties. The GFS shows some H5-H7 moisture, though
The NAM suggests too little moisture even on Thursday, so I would
not be surprised to see these slight chances of thunderstorms
removed in subsequent forecasts. We have removed thunderstorm
chances for Siskiyou County because of the expected very dry
conditions aloft.

The upper trough axis will move through Friday and Saturday,
though the trough will be fairly weak so we`re not expecting much
precipitation at all. Drizzle is possible at the Coos County coast
Friday night into Saturday morning as the marine layer deepens and
energy aloft moves overhead.

Dry westerly to southwesterly flow continues into next week, and
temperatures will warm back up slightly, with slightly above
normal readings early next week. Again, the dry flow should
prevent any significant thunderstorm outbreaks through at least
the middle of next week. ./NSK

&&

.AVIATION...For the 28/18Z TAF cycle...Primary focus for the next
24 hours will be cloud cover over the coast and umpqua valley. Upper
air forecast soundings suggest low level moisture pushing inland and
forming a stratus deck like we`ve been seeing over the last few
days.  Thinking we should see MVFR conditions and stay away from IFR
conditions with the strong coastal winds.

Eventually, offshore flow will resume tomorrow and we will mix out
cloud cover over land by the late morning.

-Smith

&&

.MARINE...Updated 800 AM PDT Tue 28 June 2016...
High pressure offshore and a thermal trough along the coast will
continue to bring gales and steep seas south of Port Orford and 10nm
or farther from shore.  As for the inner zones, current observations
show winds only around 10 knots. Thinking that the gradient is
weaker over the inner waters for this event so the winds won`t
increase in the inner waters unless the thermal trough moves farther
inland.

The thermal trough is expected to weaken slightly Friday into
Saturday.
-Smith

&&

.FIRE WEATHER...Updated 200 PM PDT Tue 28 June 2016...

Hot and dry conditions will continue this week underneath a
moderately strong ridge. The steering flow aloft is southwesterly
and this will bring a few disturbance inland. Moisture is very
limited and moderate cumulus build-ups are all we can muster.
However one side effect from these disturbance is cooler air aloft
that works to destabilize the atmosphere. As a result, part of our
fire weather zones in the east, such as eastern zone 625 from Hwy
395 east into Harney County, will see Haines Index climbing to 6. SE
Modoc County will also see Haines Index of 6 this afternoon and
Wednesday afternoon.

Moisture increases a bit on Thursday and may be enough to produce
isolated thunderstorms over the higher terrain. Currently it looks
like eastern Klamath County from Chemult southeastward to Lakeview,
and the Marble Mtns of northern California will be the most
unstable.

There will be a subtle change in the weather from Friday to the
weekend. The Low Pressure in the Gulf of Alaska will drop south and
sends a dry cold front inland. The front could weaken to a trough by
the time it drops this far south but should still have enough punch
to generate breezy conditions for areas west of the Cascades. The
eastern zones could see sustained winds 15-20 mph this weekend which
when coupled with min RH in the 15-20% could present fire weather
concern. /FB

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Friday for
     PZZ350-356-370-376.
     Gale Warning until 5 AM PDT Friday for PZZ376.

$$

BPN/NSK/CZS/FB


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