Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 211140

Area Forecast Discussion
National Weather Service Medford OR
440 AM PDT Mon Oct 21 2019

.DISCUSSION...The only exception to warmer and drier weather this
week will be a chance of very light showers for Coos and Douglas
Counties early Tuesday morning into Tuesday afternoon accompanying
a dissipating cold front.

A couple more weak shortwaves will skirt past in a northwest flow
aloft this morning, while a warm front pushes into British
Columbia and high pressure persists offshore of California. The
high will weakly and briefly build into our area today with
dissipating clouds and noticeablely warmer temperatures.

Attributes emblematic of the weakness of the aforementioned cold
front on Tuesday will be the limited coverage of a chance of
showers north of the Umpqua Divide, the briefness of an increase
of clouds (mainly afternoon and evening for a majority of the
area), and generally just a few degrees of cooling of high
temperatures on the west side compared to today. Meantime, highs
on the east side may not be any cooler at all.

High pressure will more strongly build into the west coast
Wednesday into early Friday with warmer and drier than normal
weather. This will include easterly ridge top winds from Tuesday
night into Thursday evening, with a downslope warming/Chetco
Effect for Brookings on Wednesday and Thursday with highs in the
lower 70s to lower 80s.

Precipitation looks to remain mostly or entirely north of our area
as a cold front moves southeast into the Pacific Northwest late
Friday into Friday night. Of more impact, is that this will
likely usher in a colder northerly flow this weekend into early
next week.


.AVIATION...For the 21/06Z TAFs...Coast, Offshore, and Umpqua
basin...MVFR ceilings are expected through the morning. Patchy IFR
ceilings, especially near the coast are possible and more widespread
mountain obscuration into Monday morning. No LIFR conditions were
included in the TAFs despite MOS guidance showing this. Isolated
pockets of LIFR are certainly possible but are not common in
climatology, visible in model soundings, nor LAMP guidance. Some
improvement to VFR is expected late Monday morning or early Monday

Elsewhere, Mountain obscuration and a mix of VFR/MVFR ceilings will
continue into the morning. Patches of valley MVFR are likely mid-
Monday morning. Soundings did show IFR at Klamath Falls but does not
match any other guidance. Improvement is expected late Monday


.MARINE...Updated 830 PM PDT Sunday 21 October 2019...West
swell will continue to lower slowly today. But, south winds will
remain moderate through the morning. The combination of wind waves
and swell will produce steep seas north of Cape Blanco and within 10
NM from shore. These conditions should diminish below those
hazardous to small craft by early morning.

High pressure builds over the offshore waters and will build in
Monday, weakening a front that will brush the waters north of Cape
Blanco late Monday night into Tuesday.

High pressure aloft will strengthen mid-week with a thermal trough
deepening over the south coast. This will result in gusty north
winds and likely steep to very steep wind driven seas, with the
strongest winds and highest seas south of Cape Blanco. This pattern
will persist into Thursday. -Keene/Miles




Pacific Coastal Waters...None.


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