Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 201028

Area Forecast Discussion
National Weather Service Medford OR
328 AM PDT Fri Oct 20 2017


Scattered showers will continue across the region this morning
behind a robust cold front. Snow levels have dropped and we have
observed snow falling at Lakeview, Klamath Falls and the Diamond
Lake ODOT camera this morning. We`re still going with 6 to 10
inches to fall above 4500 feet across the Cascade range this
morning through 18z. We also saw plenty of precipitation with one
site near Brookings reporting 2+ inches of rain.

As for the rest of the day, the trough axis swings through our
forecast area with the cold temperatures aloft allowing widespread
showers to continue. The bulk of precipitation will occur during
the morning and early afternoon hours before the trough axis
swings through Friday afternoon/evening. As a result, showers
should be on the down turn Friday evening.

That will be briefly lived as a warm front pushes in from the
west on Saturday morning. Snow levels will still be 4000 to 4500
feet ahead of the front. Therefore, broad synoptic lift ahead of
the front will allow for some pretty intense snow fall between
6z and 15z Saturday along the Cascades. Right now the forecast
calls for an additional 6 to 10 inches along the Cascades.

Once this warm front passes, the focus really is on the zonal flow
and the atmospheric river slamming onto the Cascade range. Right
now Portland`s forecast area is really going to get hit if the
models are on point. 700mb and 850mb winds are 50 to 60 knots
allowing for some solid topographic lift, which can be seen on the
NAM QPF output. More specifically for the QPF fields from 21z
Saturday to 18Z Sunday. That moisture axis will then shift south
briefly Sunday evening bringing more rain to southern Oregon. Wind
products may be needed for higher elevations on east side
Saturday afternoon because of the winds mentioned earlier.



.AVIATION...20/06Z TAF Cycle...From the Cascades west...Areas of
MVFR/IFR cigs/vsbys in showers and extensive obscuration of higher
terrain will persist into Friday morning. Conditions will improve
Friday morning to local MVFR cigs in showers with areas of higher
terrain obscured. This will persist into Friday evening, but
precipitation will end briefly Friday afternoon into Friday evening.
East of the Cascades...Areas of MVFR cigs/vsbys with obscuration
of higher terrain will persist into Friday morning. Conditions will
improve to isolated MVFR cigs by Friday afternoon, but winds will
pick up again Friday afternoon. Precipitation will end briefly
Friday afternoon into Friday evening. -Spilde


.MARINE...Updated 320 AM PDT Friday 20 October 2017...Heavy long
period northwest swell is in the waters. This is creating very high
and steep seas along with dangerous surf and bar conditions.
Northwest swell will slowly subside tonight. However, around that
time another round of strong south gales will develop as a warm
front moves through the area. Gale force winds are likely over most
of the area. Winds and seas will subside again Saturday.

A thermal trough will set up along the coast early next week, and
this will bring strong north winds and steep seas south of Cape
Blanco beginning Monday and continuing through Tuesday. -Sven


OR...High Surf Advisory until 11 PM PDT this evening for ORZ021-022.
     Winter Weather Advisory until 11 AM PDT Saturday for


Pacific Coastal Waters...Hazardous Seas Warning until 11 PM PDT this evening for


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