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fxus66 kmfr 212131 

Area forecast discussion
National Weather Service Medford or
231 PM PDT Sat Sep 21 2019

Discussion...don't be fooled by the clear skies and warmer
temperatures today, as the next front will arrive tomorrow,
bringing cool and wet weather back to our area once again.
Precipitation should begin moving into the coast by sunrise, then
spread inland through the rest of the day before ending late in
the evening and overnight. Models, especially higher resolution
suites, continue to show a later arrival of the precipitation
than previous runs, so there have been some forecast changes to
accommodate this trend.

By Tuesday morning, high pressure will once again build into the
region, resulting in dry, mostly clear weather and a gradual
warming trend until the next significant system arrives Thursday.
Until then, morning valley fog may be a common sight in the
region, especially in the coastal valleys. While high pressure
will be in control over the forecast area and offshore winds are
likely over the South Coast, a zone of swift mid to upper level
northwest flow is expected over far northern Oregon and
Washington. Some weak impulses within the flow could produce a
period or two of increased clouds and perhaps even a light shower
along the north coast, but the vast majority of the area should
see little in the way of impacts from any such feature.

The next front is expected to arrive late Thursday or Friday, but
there is wide enough spread in the GFS and ECMWF, along with
their respective ensembles, that confidence in arrival time and
strength of the system is highly uncertain. The overall pattern,
however, does suggest that wet weather and cooler temperatures
will arrive just in time for next weekend. -Bpn


Aviation...for the 21/18z tafs...the stratus has cleared with VFR
conditions across the area remaining into this evening. Low clouds
will return again late tonight at the coast and into the Umpqua
basin around Roseburg with fog at the coast. -Sven


Marine...updated 130 PM PDT Saturday 21 September 2019...high
pressure offshore and a thermal trough along the coast will persist
through this evening. Gusty north winds will lead to steep seas
hazardous to small craft south of Port Orford.

Conditions improve tonight into Sunday as the thermal trough pattern
gets interrupted ahead of the next front. The front is expected
Sunday. Winds will briefly turn southerly ahead of this front, but
are expected to remain below advisory level. Expect a period of
showers and the possibility of thunderstorms as the front moves
inland Sunday afternoon and evening. Seas will also build with this
frontal passage as northwest swell moves into the waters. Monday
into Wednesday, the thermal trough quickly redevelops, bringing the
return of northerly winds (possible gales) and steep wind driven
seas, especially south of Cape Blanco. The next disturbance is
expected around Thursday and may be accompanied by a building, large
northwest swell. -Spilde/sven


Mfr watches/warnings/advisories...


Pacific coastal waters...Small Craft Advisory until 5 am PDT Sunday for pzz356-376.

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