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  Forecast Discussion for Southern Oregon and Northern California  

Forecast: Forecast Discussion | 7 Day Forecast

Forecast Discussion for MFR NWS Office

000
FXUS66 KMFR 250300
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
800 PM PDT SAT SEP 24 2016

.DISCUSSION...25/00Z NAM IN.

A strong long wave ridge has built into the area from the west
with northwest flow aloft. Skies have cleared over the entire CWA
as low level easterly flow sets up over the area. The easterly
flow will peak tonight and a Red Flag Warning is in effect for the
ridges of extreme southwest Oregon and western Siskiyou County for
gusty winds and poor RH recoveries.

The ridge will move very slowly east through the area with the
ridge axis breaking to the east Sunday evening. Dry weather will
continue and temperatures will warm through Monday.

It warmed up quite a bit Saturday with inland high temperatures
10 to 20 degrees warmer than the Friday highs. These values ranged
from near normal to around 5 degrees above normal. Sunday will be
even warmer...generally 10 to 15 degrees above normal. The south
coast will be toasty as well due to the Chetco effect...the
Brookings high will be around 90.

The upper ridge axis will move onshore Sunday...and this will
cause the thermal trough to move onshore. This will end the
easterly wind event. It will be cooler at the coast Monday...but
Monday will be the hottest day over the west side with the thermal
trough overhead. Inland highs will be 15 to 20 degrees above
normal.

A weak front will move onshore Tuesday morning. It will be dry
except for possible drizzle along the coast. The associated
marine push will cool temperatures around 10 degrees on the west
side Tuesday. The east side and northern California will also be
cooler...but only by a few degrees.

Extended discussion from the Saturday afternoon AFD...Wednesday
through Saturday. We`ll remain above normal, but trend cooler
Wednesday into Thursday as an upper level trough dives
southeastward from the Gulf of Alaska. We`ll be in a broad
southwesterly flow aloft which will likely keep us dry, but
heights will lower some.

Shortwave disturbances associated with the upper trough will
rotate onshore Friday into next weekend, the strongest of which
looks to arrive Saturday. Details are likely to change over the
next several days, but it looks like we`re headed for another shot
of cool, wet autumn weather. -Spilde

&&

.AVIATION...25/00Z TAF CYCLE...VFR CIGS will continue for the next
24 hours for all terminals. However, guidance does suggest there is
a chance for patchy shallow fog and possible reduction of visibility
at North Bend around 11z Sunday. Decided to add this into the TAF
because surface winds could become light from the southeast which
sometimes favors low level moisture development. -Petrucelli

&&

.MARINE...Updated 800 PM PDT Saturday 24 September 2016...The
thermal trough is now developing just off the south coast. North
winds are increasing and seas are becoming choppy. Winds will
continue to increase through tonight. Winds will be strongest south
of Gold Beach. Small craft winds will expand north south of Cape
Blanco late Sunday morning through Sunday night and could sneak into
the southern inner waters between 8 and 10 nm from shore. The trough
will weaken briefly Monday with lower winds and seas...but it will
redevelop Tuesday into Wednesday after a weak front moves onshore.
Strong north winds will return...possibly reaching gale force by
midweek south of Cape Blanoc.  Winds will weaken agaian Wednesday
night into Thursday as another weak front approaches the coast.

&&

.FIRE WEATHER...Updated 800 PM PDT Saturday 24 September 2016...
Gusty northeast to east winds and poor humidity recoveries will
impact Fire Weather Zones 618, 619, and 280 tonight. These
conditions are expected only over the upper slopes and ridges of
these areas. Other areas will be breezy with moderate to isolated
poor humidity recoveries tonight and Sunday morning, including the
Siskiyous and Cascades. It should be noted that the 100+ lightning
strikes that occurred on Wednesday could show themselves over the
next 72 hours as conditions become very hot and dry, and windy in
the aforementioned Red Flag Warning areas.

Wind speeds peak tonight and Sunday morning, then humidities really
take a nose-dive Sunday through Monday. Both days will be extremely
dry, and recoveries Sunday night will be moderate to poor again in
many locations. Some of the coastal mountain sites may not get out
of the teens Sunday night. Wind speeds should be generally less
Sunday night compared to tonight and perhaps strongest in the
Cascades, but this is where widespread wetting rains occurred
earlier this week, so conditions should not be as critical there.
Still, it`s a very dry pattern, and we will continue to headline
much of the area for the next few days and watch it closely.

Lastly, models are coming into better agreement with the chance for
wetting rains for much of the area from the Cascades westward this
weekend. SK

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from midnight tonight to 10 AM PDT Sunday for
        ORZ618-619.

CA...Red Flag Warning from midnight tonight to 10 AM PDT Sunday for
        CAZ280.

Pacific Coastal Waters...Small Craft Advisory for hazardous seas
        until 5 AM PDT Monday for PZZ350-356-370-376.
     Small Craft Advisory until 5 AM PDT Monday for PZZ376.

$$

15/15/15

NWS MFR Office Area Forecast Discussion