Flood in Oregon, January 10 to 13, 2017

Area Forecast Discussion
National Weather Service Medford OR
810 PM PST Mon Jan 9 2017

.DISCUSSION...10/00Z NAM in. 10/00Z GFS in through 84hr.

Another busy evening weatherwise around the Medford CWA. A strong
band of showers and isolated thunderstorms moved onshore Monday
afternoon and is moving slowly through the area. It brought
periods of heavy rain to the west side and earlier this evening
there were a lot a reports of snow as low as 1000 feet or so. Now
it is bringing snow to the east side as well. Snow levels will
rise to 3000 feet later tonight...so the snow will change to rain
over the west side valleys.

The next system will move in Tuesday morning and there is
uncertainty with the trajectory of the surface low, which will be
critical for the wind forecast along the coast. The 10/00Z NAM and
10/00Z GFS solutions have converged a bit with this feature, and
it now appears that there will an area of south gale force winds
over the coastal waters south of Cape Blanco, but winds onshore
will not meet High Wind Warning criteria.

There is a lot more coming at us over the next week, and it was
covered pretty well by the day shift. Their discussion follows
below with some light editing.

&&

.AVIATION...10/00Z TAF CYCLE...Conditions will vary from VFR to MVFR
west of the Cascades this evening with terrain obscured in
widespread showers and snow showers. Gusty low level southerly winds
are expected along the coast and over the east side. Freezing levels
will be 3000 to 3500 feet. Showers and snow showers will continue
tonight and freezing levels will rise reaching to around 5000 to
6000 feet on Tuesday.

East of the Cascades....Mainly VFR but MVFR with occasional light to
moderate snow showers and areas of higher terrain obscured. Snow
showers will increase tonight.

The next storm will arrive Tuesday morning along the coast with
increasing south winds and moderate to heavy precipitation spreading
inland from southwest to northeast. Expect mostly MVFR/vfr
conditions through the remainder of the TAF period. -Spilde/BPN

&&

.MARINE...Updated 800 PM PST Monday 9 January 2017...A
combination of southwest wind waves and fresh swell is producing
high and very steep seas. There will also be numerous showers with
a chance of thunderstorms through tonight. Thunderstorms could
produce gale force winds and small hail, as well as frequent
lightning. Seas will build tonight while a front brings an
increase in advisory strength southwest winds that may briefly
gust to gale force for a few hours late tonight. Seas will peak at
around 17 feet at 12 seconds early Tuesday morning.

A strong area of low pressure will bring gales to the northern
California and far southern portion of the Oregon waters for a few
hours during late Tuesday morning into the afternoon. The track of
the low is uncertain but it will bring shifting winds with a period
of easterly winds likely over the northern portion of the waters
while the strong southerly winds occur over the far south.

Conditions will slowly begin to improve Tuesday night though the
next in the series of fronts will likely continue small craft
advisory winds and very steep seas into Wednesday. High pressure
will then move in late Wednesday with diminishing seas and calmer
winds at least into Friday. -DW/BPN

&&

.PREV DISCUSSION... /Issued 347 PM PST Mon Jan 9 2017/

DISCUSSION...Snow levels rise to 3000 feet over most areas
tonight, and our Winter Storm Warnings are generally for areas
3000 feet and higher. Some of the highest impact areas will be the
High Cascades and the Mount Shasta City area where heavy snow will
continue into tomorrow. The heaviest periods of snow in the
Cascades are expected to be Tuesday afternoon as an atmospheric
river pushes into the forecast area. One added point of concern
will be strong winds accompanying some of the heavy snow in the
Cascades, leading to the possibility of downed trees.

Snow levels will push above 3000 feet tomorrow, and some areas
like Mount Shasta City and Union Creek will transition to rain in
the late morning or afternoon. The east side will see moderate to
heavy snow, with the highest impacts expected along Highway 97
near Chemult where about 18 inches of snow is forecasted.
Moderate to strong winds will impact areas east of the Cascades,
and blowing and drifting snow is expected.

Lots of flood products have been issued as well, and we have Flood
Warnings out for the Coquille at Coquille, the South Fork of Coquille
at Myrtle Point, and the Rogue River at Agness. Additionally, we
have an Areal Flood Watch for the Curry County Coast for expected
high rainfall rates on Tuesday. Lastly, we have flood advisories
out for much of the West Side and over Northern California. With
reports of flooding (high water on roadways and rising streams) already
having been reported yesterday and today, we expect flooding
impacts to only increase tomorrow with periods of heavy rain.

Snow levels drop Tuesday night behind a cold front, but
precipitation should diminish as well. Still, there could be
winter weather impacts and lingering flooding concerns before
precipitation comes to an end later in the week.

Wednesday through Sunday...The long wave trough that brought all
the nasty weather to the forecast area for the last week will
finally push to the south and east of the CWA Wednesday night.
Snow levels will drop to as low as 500 feet west of the Cascades
by Thursday morning, but this will be just in time for
precipitation to end from northwest to southeast, so west side
impacts from snow should be minimal. Water levels from the early
week flooding should begin to recede as colder air moves in aloft.
So, it should be noted that any wet/slushy roads left from the
storminess earlier in the week across the west side will likely
re-freeze, so black ice will remain a concern.

High pressure will build east of the Cascades on Thursday, so it will
be dry area wide, but temperatures will be around 10-15 degrees below
normal. A frigid night is expected Thursday night. We have lowered
minimum temperatures with upper ridging building in providing clear
to partly cloudy skies and great radiational cooling. Some low
clouds and freezing fog are possible over the valleys, especially
the west side late at night and into Friday morning.

Model guidance continues to be at odds with respect to the next
system moving into the area Friday night into Saturday. The GFS is
stronger bringing a period of precipitation to the coast and Umpqua
to the Cascades, but the ECMWF is much weaker with little, if any
precipitation at all impacting our CWA. Have split the difference
here and backed off the previously higher POPs we had in for this
time period.

Models then bring brief ridging back into the area Saturday night
into Sunday morning before the next system arrives at the coast
Sunday afternoon. -Spilde

Sunday afternoon through Tuesday morning...The timing differences among
the models continue, but both generally agree on the progressive
pattern continuing. The EC is faster in bringing the next system
onshore and spreading precipitation inland during the day Sunday, while
the GFS keeps precipitation offshore until late Sunday night. The
faster EC solution would allow for a brief break in the precipitation
Monday afternoon, while the GFS maintains post-frontal showers through
Tuesday morning.

Both models are depicting zonal flow aloft, so not expecting any cold
snaps during this time considering that zonal flow aloft typically
indicates "normal" weather and have adjusted the forecast to reflect
this. Although there were timing differences between the models, went
with a general blend with a lean toward climatology to include higher
POPs along the coast and north of the Umpqua, with lesser POPs south
and east. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 PM PST Tuesday for ORZ029>031.
     Winter Storm Warning until 10 PM PST Tuesday for ORZ029>031.
     Winter Storm Warning until 10 PM PST Tuesday ABOVE 3000 FEET for
        for ORZ025-027-028.
     Flood Watch from 4 AM PST Tuesday through Tuesday evening for
        ORZ022.
     Winter Weather Advisory until 8 PM PST this evening ABOVE 1500
        FEET for for ORZ024.
     Winter Storm Warning until 10 AM PST Tuesday ABOVE 3000 FEET for
        for ORZ024.
     Wind Advisory from 9 AM to 7 PM PST Tuesday for ORZ026.

CA...Winter Weather Advisory until 10 PM PST Tuesday for CAZ084-085.
     Winter Storm Warning until 10 PM PST Tuesday for CAZ084-085.
     Winter Storm Warning until 4 PM PST Tuesday ABOVE 3000 FEET for
        for CAZ082-083.
     Winter Storm Warning until 10 AM PST Tuesday ABOVE 3000 FEET for
        for CAZ080.
     High Wind Warning from 7 AM to 10 PM PST Tuesday for CAZ081.
     Winter Weather Advisory until 4 AM PST Tuesday for CAZ081.
     Wind Advisory from 7 AM to 10 PM PST Tuesday for CAZ081.

Pacific Coastal Waters...Gale Warning from 10 AM to 8 PM PST Tuesday
        for PZZ356-376.
     Hazardous Seas Warning until 10 PM PST Wednesday for
        PZZ350-356-370-376.

15/15/15

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1034 PM PST MON JAN 9 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1032 PM     SNOW             2 SW CHILOQUIN          42.55N 121.90W
01/09/2017  M4.0 INCH        KLAMATH            OR   TRAINED SPOTTER

            4 INCHES OF SNOW SINCE 1600 PST. TEMPERATURE
            30 DEGREES. ELEVATION ABOUT 4400 FEET. . THE
            DURATION OF THE SNOW EVENT WAS 6 HOURS 30
            MINUTES.

&&

JRS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1239 AM PST TUE JAN 10 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 AM     HEAVY RAIN       2 ESE ASHLAND           42.18N 122.66W
01/09/2017  M1.06 INCH       JACKSON            OR   TRAINED SPOTTER

            . THE DURATION OF THE HEAVY RAIN EVENT WAS
            24 HOURS. THE REPORTED OBSERVER LOCATION WAS
            2 MI. S. OF ASHLAND AIRPORT.

&&

FB