Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 181801

Area Forecast Discussion
National Weather Service Medford OR
1001 AM PST Fri Jan 18 2019

Corrected to clarify that a Flood Watch is in effect, not a
Flash Flood Watch.

.DISCUSSION...18/12Z NAM in. 18/12Z GFS in through
bits and pieces.

The hemispheric view shows a wave number of four around the globe.
Normally this is a progressive pattern, and initially it will be.
However, the pattern will stall in the extended period.

In the near term it will be very wet and occasionally windy with
high snow levels. An upper level ridge will break to the east of
the area today. A surface warm front will move in from the
southwest, bringing precipitation to most of the area later today
into tonight. Initial rain rates will be light to moderate.

However, that will change as the upper ridge moves out and
southwest winds aloft increase over the area. The trailing cold
front will move into the area tonight, but it will stall as it
becomes parallel to the steering flow. Weak waves will form and
move northeast along the frontal boundary.

This will make for a long period of significant precipitation
tonight into Sunday, occasionally enhanced as the frontal waves
move through. The heaviest amounts will fall over western
Siskiyou county and extreme southwest Oregon. Precipitation totals
from this afternoon through Saturday night will be impressive.
From the Cascades west, totals will range from around an inch in
the Rogue and Shasta valleys to nearly 10 inches in the Coast
Range above Brookings. A Flood Watch is in effect for portions of
the west side. See PDXFFAMFR for details.

Winds will be a factor as well this afternoon into Saturday
morning, and many areas will see Wind Advisory level winds. There
is also a High Wind Warning for the coast, mostly from around Cape
Blanco south. See PDXNPWMFR for details.

On top of all that, there will be heavy surf as well today. See
PDXCFWMFR for details.

The upper level trough will approach the coast Sunday, and this
will unstall the front and force it inland. The heavy
precipitation will diminish, but post-frontal showers will
persist until the upper trough, and the waves diving down the
backside of it, clear out to the east Monday evening.



.AVIATION...For the 18/18Z TAFs...Low level wind speed shear will be
the main concern today for North Bend, Roseburg and Medford. Wind
shear could start out at 1500 at the coast and Medford later this
morning, then 2000 feet this afternoon. In the umpqua Basin,
including Roseburg, it is expected to be at 1500 feet later this

The freezing level on the sounding at medford was 4,900 feet, but
it`s expected to rise to around 7000 feet later this morning and
8500 feet this afternoon.

East of the Cascades, we`re expecting snow to continue this morning,
but a change over to rain is likely within the next 3 hours.  Given
the warmer road temperatures and the freezing level around 4900
feet, we`re not expecting over 1 inch of snow in Klamath Falls.
LIFR will prevail until 1 pm or so as snow continues to fall, but
a mix of MVFR and IFR are expected in the afternoon.

 As for CIGS and visibilities today,  MVFR and IFR will remain
dominant in the valleys and along the coast.  All the added moisture
in the valleys will likely result in more IFR fog Friday night and
Saturday morning.



.MARINE...Updated 800 AM PST Friday 18 January 2019...Gales will
persist in the waters this morning through Saturday morning.  The
strongest winds will occur 5 to 15 nm away from shore and north of
Cape Blanco.  Waves will also remain hazardous through this weekend
as fresh swell and a high and steep west swell combine to create
hazardous seas.  Eventually high pressure will build Sunday and seas
will begin to settle around that time.  They may remain hazardous to
smaller crafts at times as storm systems still remain present well
to our west.

Hazardous surf conditions will continue into early this morning.
Surf heights will slowly drop, and fall below advisory thresholds
this afternoon as wind waves become dominant. Please CFWMFR for more



OR...Wind Advisory from 4 PM this afternoon to 10 AM PST Saturday for
     High Wind Warning until 4 AM PST Saturday for ORZ021-022.
     Flood Watch from 4 PM PST this afternoon through late Saturday
     night for ORZ021-022-024.
     High Surf Advisory until 1 PM PST this afternoon for ORZ021-022.
     Wind Advisory until 4 AM PST Saturday for ORZ023-024.
     Wind Advisory until 4 AM PST Saturday for ORZ026.

CA...Flood Watch from 4 PM PST this afternoon through late Saturday
     night for CAZ080.
     Wind Advisory until 10 AM PST Saturday for CAZ081.

Pacific Coastal Waters...Gale Warning until 4 AM PST Saturday for PZZ350-356-370-376.
     Hazardous Seas Warning until 10 AM PST this morning for

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