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Area forecast discussion 
National Weather Service Medford or
307 PM PDT Thursday Oct 8 2015

Added fire weather discussion.

Discussion...the upper ridge axis is centered east of the Cascades
with a west to southwest flow aloft bringing a few high clouds
into the area. Generally we'll continue to have mostly clear skies
through tonight. Temperatures have been warming up, but as is
normal for this time of the year the amount of warming has been
slow. Still we should see reading in the lower to middle 80s for
Westside valleys and upper 70s to lower 80s east of the Cascades.
With skies remaining mostly clear tonight, we expect temperatures
to fall off quickly after dark with cooler readings expected
Friday morning.

The main concern ahead is the remnants of oho which has been drawn
into the upper trough to our west and is rapidly accelerating
northeastward towards southern b.C. This will bring an increasing
long period southwest swell tonight through Friday night with high
and steep seas Friday night through the weekend. Please see the Special Weather Statement
mws for details on the impact and precautions that should be

The GFS and NAM show a weak front moving into the area Friday
afternoon. Precipitation should be very light and most will be along
the coast and northwest Douglas County. Further inland we
probably won't get anything. Temperatures Friday could end up a
little cooler north of the Umpqua Divide and coast, but expect
similar readings elsewhere. The upper trough is expected to dig
further on Saturday and move inland Saturday night. At the
surface, a stronger front will reach the coast Saturday afternoon,
then move inland Saturday night. This front will bring a better
chance at measurable rainfall for the coast, coastal mountains,
north Cascades and north of the Umpqua Divide. Rainfall amounts
will be higher, but nothing significant.

Meanwhile 700mb winds will increase Saturday and could peak out
between 40-50 kts Saturday afternoon and evening. Therefore gusty
winds are a good bet along and east of the Cascades, especially over
the higher terrain and near Summer Lake and will be strongest in the
afternoon and early evening. Its possible a few of the higher ridges
could get close to advisory criteria, so its something that will
need to be watched closely.

The upper trough will swing through the area Saturday night followed
by weak upper ridging Sunday. Any rainfall will end early Sunday
morning with drying and milder temperatures in the afternoon.

The ec and GFS show similar solutions for the first half of next
week showing a dirty ridge scenario. The position of the ridge is
such that the storm track should remain north of our area and we'll
continue to have dry and warm conditions with varying amounts of
high and middle level clouds moving through. One fly in the ointment is
both models show a cutoff upper low moving near or over southern cal
next Wednesday, then slowly moving inland Thursday. The models
differ with the position of the upper low but keep it far enough
south to have any impact in our area. Of note, several members of the
ensemble mean also have the low positioned just off the coast of
southern cal. For now we'll keep the extended dry with low probability of precipitation
confined to Modoc County. -Petrucelli


Aviation...current visible image shows the marine stratus
offshore, but has been slowly advancing towards the coast. Its
possible it could reach North Bend with MVFR and local IFR ceilings
developing. Current taf keeps VFR conditions through the night, so
it will need to be watched closely. A front will approach the
coast Friday and south winds will increase with a chance for wind
speed shear near or above 1500 feet from the surface from Cape
Blanco north. Elsewhere VFR conditions will continue for the next
24 hours. A middle cloud deck will move into the Umpqua bringing
cloud bases of 4-6 kft at krbg around 16z. -Petrucelli


Marine...updated 1100 am PDT Thursday, 8 Oct 2015... high pressure
will continue south winds and low seas through this afternoon. Winds
will increase and southwest seas will build this evening through
Friday night as the first front in a series arrives from the west. A
Small Craft Advisory for winds has been issued for portions of the
area associated with this first front. Late Friday afternoon through
Saturday long period southwest swell 11 to 14 feet at 16 seconds
will arrive from the remnants of central Pacific hurricane oho. This
is likely to result in 15 to 20 foot breaker heights. Swell of this
magnitude is unusual for this area, so an marine weather statement
at mwsmfr has been issued to highlight potential impacts to
mariners. A Special Weather Statement at spsmfr has also been issued
to discuss probable impacts to beach goers. Saturday into Sunday a
slightly stronger front is expected to bring rain and gusty south
winds, while southwest swell becomes westerly and remains elevated.


Fire weather...updated 300 PM PDT Thursday, 8 Oct 2015... the first
in a series of frontal systems will reach coastal areas with some
light rain or drizzle on Friday and dissipate as along the coast
late Friday. This front will have little impact inland though and
expect inland areas to remain dry on Friday. Saturday into Sunday a
stronger frontal boundary will push onto the coast with some wetting
rainfall possible on the west side, primarily along and near the
coast and across Douglas County. Other than the coast and Douglas
County, there is low confidence in how much rainfall may occur and
models vary from little rainfall in west side valleys in southern
Oregon to 0.10 to 0.20 inches of rainfall. Southwest winds are
likely to be gusty Saturday afternoon and evening, especially from
the Cascades eastward, but relative humidities are not expected to
be critical. Temperatures today and Friday will be 10 to 15 degrees
above normal and are likely to fall to only 5 to 10 degrees above
normal this weekend. /Cc


Mfr watches/warnings/advisories...


Pacific coastal waters...hazardous seas warning from 5 am to 5 PM PDT Friday for
Small Craft Advisory for winds from 2 am to 5 PM PDT Friday for


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