Hazardous Seas Warning 9, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
239 PM PST Sat Feb 4 2017

.DISCUSSION...A moist west to southwest flow aloft with embedded
shortwaves will continue into tonight. Therefore we can expect
showers to persist with most of them concentrated along the south
coast, Coast Range and Cascades.

Gusty winds are still in the cards, especially east of the Cascades
where wind advisories remain in effect. In fact the models suggest
it will remain windy into early this evening, therefore have
extended the end time until 7 pm pst.

The models suggest a brief break is possible early Sunday morning,
but confidence is low on how long or if we get any break. The reason
is a frontal boundary is expected to remain nearly stationary over
our area tonight into Sunday morning. This front should lift north
some during the day Sunday as low pressure develops along the front
near 30 N and 135W and tracks through our northern coastal waters
Sunday afternoon. The low will then move onshore Sunday evening. As
a result, the focus for heavy precipitation should be just to our
north, but if the surface low ends up tracking further south, then
heavy rain could impact areas mainly from Cape Blanco North.

Meanwhile inland away from the coast and east of the Cascades,
precipitation will decrease and could end altogether from around mid
morning Sunday into Sunday afternoon and there's a chance we could
see some brief clearing. This could allow south to southeast winds
to surface and much like last Thursday allowing temperatures to jump
up. The forecast high of 61 for Medford is not unreasonable if the
above mentioned scenario pans out. Also snow levels should remain
high (between 5000-5500 feet), therefore any road snow impacts
should be limited to Diamond Lake and Crater Lake.

Of bigger concern will be moderate to strong winds at the coast,
Shasta Valley and east of the Cascades. Confidence is high we'll
reach high wind criteria for these areas and have upgraded the high
wind watches to a warning for these areas. In addition we also
issued a wind advisory for portions of the Shasta Valley, eastside
and south end of the Rogue Valley. Confidence is not as high in
terms of the coverage area in the Rogue Valley, especially in White
City and Eagle Point, but it is higher from around Talent south to
Ashland. Please see NPWMFR for details.

The upper trough will push southeast towards the Oregon coast Sunday
night and this will send a strong cold front in the northwest part
of the forecast area early Monday morning, then moving onshore
during the day with snow levels falling quickly. Just about everyone
across the CWA will have a period of rainfall with the front Sunday
night into Monday morning. Since the front will be moving through
fairly quickly, we're not expecting more than some minor rises on
area creeks, streams and rivers. In the higher passes like Lake of
the Woods, Siksyou Summit could experience snow covered roads by the
early morning commute early Monday morning with snow levels expected
to be around 3500-4000. Meanwhile snow levels will fall to around
2000-2500 feet west of the Cascades Monday morning. However due to
the quick nature of the front, snow amounts for the above
mentioned passes should be minor.

We'll catch a relative break in the weather Monday night into early
Tuesday morning, then warm frontal precipitation is expected to move
up from the southwest Tuesday morning into Tuesday afternoon. The
models are in disagreement with the details. it's possible snow
levels could start out around 2500 feet Tuesday morning, then
jumping up to 5000 feet Tuesday afternoon, but it's all going to
come down to timing. If the warmer air is slower to move in, then we
could be dealing with significant snow for the mountains in Siksyou
County, Mount Shasta region and cascades. As we move closer to this
time period, we'll be monitoring the potential for this.
-Petrucelli

Long term...Wednesday morning through Saturday night...Overall, the
models are in fairly good agreement throughout the extended, with
the exception of Thursday. By Wednesday morning, a warm front is
expected to have passed through the area in advance of a short lived
upper level ridge. This will maintain high snow levels as the upper
ridge temporarily builds over the area through Wednesday.
Precipitation will be scattered and light during the morning, before
picking up in intensity as an atmospheric river event moves into the
coast by Wednesday afternoon. Snow levels will be high during this
event, to the tune of 8500 feet, so moderate to heavy rain on snow
will be a concern. However, the AR event is expected to be short
lived as cold air is expected to move in Thursday afternoon, and
this should minimize flooding concerns.

Thursday seems to be the one day that the models disagree
significantly. By Thursday morning, the GFS spins up a surface low
inside of 130W, moving it north along the PacNW coast and into
towards Vancouver Island. The EC does not show this and instead
maintains a broad surface low centered out near 140W. The difference
in solutions leads to significant differences in winds for the area.
If the GFS is right, winds would be quite strong along the coast and
over the waters, with breezy to gusty conditions inland. The EC on
the other hand, would still have breezy and gusty winds, just not as
significant. Confidence is low in the GFS solution at this point as
it is only the second model run to show this. Also, looking at the
GFS Ensembles, there are only a few members to show this solution.
For now, went with a blend of the two models with more of a lean
towards the EC and previous forecast. Either way, it will be windy
and wet Thursday with heavy rain expected along the coast and into
western Siskiyou county.

Snow levels will come down to around 4500 feet Thursday night and
showers are expected to continue through Saturday as the upper level
trough passes to the east. Current model runs are showing a drying
trend Saturday afternoon as an upper level ridge nudges into the
area. /BR-y

&&

.AVIATION...04/18Z TAF Cycle...Showers will be widespread across the
area today. Expect a variety of VFR/MVFR cigs across the area with
mostly VFR prevailing away from the coast where IFR cigs are likely
through tonight. Widespread terrain obscurations are also likely
through tonight. Cigs/vis could temporarily lower to IFR conditions
in heavier showers today.

A low pressure approaches from the southwest late tonight. Low level
wind shear is expected along the coast and over the waters.
Depending on the exact track, low level wind shear could be possible
for KRBG as well. Confidence was not high enough to include in the
KMFR TAF, but it's not completely out of the question and depends on
how soon winds increase at the surface early Sunday morning. Either
way, there will be gusty low level southerly winds across the whole
area with higher gusts at the coast, over the mountains, in the
Shasta Valley, and across the east side. /BR-y

&&

.MARINE...Updated 245 AM PST Saturday 4 February 2017...
Today southerly winds will remain near or above advisory strength
while seas remain high and very steep at 10 to 12 feet at 9 seconds.
Seas may briefly lower to 9 to 10 feet this afternoon then build
again this evening and tonight.

As a Pacific low approaches the waters from the southwest on Sunday,
winds and seas are expected to increase. Storm to gales force south
winds are possible across most the waters. The strongest winds with
storm force gusts possible are expected for the waters beyond 5 nm
from shore from Cape Arago southward to Port Orford and beyond 12 nm
from shore south of Port Orford. Far northwest portions of the
waters may see west to northwest winds of 20 to 25 kt on Sunday,
mainly north of Winchester Bay and beyond 40 nm from shore from
Bandon north. Gales force winds may continue Sunday evening from
Cape Blanco south. Seas are expected to build Sunday morning through
Sunday evening with very steep seas of 15 to 20 feet possible. Then
highest seas are expected from Cape Arago south.

Seas will lower on Monday. However an active pattern will continue
through week and additional fronts may bring increased winds and
periods of steep to very steep seas Tuesday and Wednesday. Then a
very strong front is possible late in the week and may bring another
round of strong winds and very steep and high seas. /CC

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 10 AM Sunday to 1 PM PST Monday for
     ORZ029>031.
     Wind Advisory until 7 PM PST this evening for ORZ030-031.
     Wind Advisory from 10 AM Sunday to 1 PM PST Monday for
     ORZ029>031.
     Winter Weather Advisory until 4 AM PST Sunday for ORZ027.
     High Wind Warning from 4 AM to 10 PM PST Sunday for ORZ021-022.
     Wind Advisory from 10 AM to 10 PM PST Sunday for ORZ026.

CA...High Wind Warning from 10 AM Sunday to 1 PM PST Monday for
     CAZ085.
     Wind Advisory until 7 PM PST this evening for CAZ085.
     Wind Advisory from 10 AM Sunday to 1 PM PST Monday for CAZ085.
     High Wind Warning from 4 AM Sunday to 1 AM PST Monday for
     CAZ081.
     Wind Advisory from 4 AM Sunday to 1 AM PST Monday for CAZ081.

Pacific Coastal Waters...Storm Warning from 4 AM to 7 PM PST Sunday for
     PZZ350-356-370-376.
     Gale Warning from 4 AM to 7 PM PST Sunday for
     PZZ350-356-370-376.
     Hazardous Seas Warning until 4 AM PST Sunday for PZZ350-356.
     Hazardous Seas Warning from 7 PM Sunday to 4 AM PST Monday for
     PZZ350-356.
     Hazardous Seas Warning until 4 AM PST Monday for PZZ370-376.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1013 AM PST SAT FEB 4 2017

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

0930 AM     HEAVY RAIN       5 NNE SELMA             42.35N 123.57W
02/04/2017  M1.38 INCH       JOSEPHINE          OR   TRAINED SPOTTER

            . THE DURATION OF THE HEAVY RAIN EVENT WAS
            24 HOURS.

&&

BS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1014 AM PST SAT FEB 4 2017

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

1000 AM     HEAVY RAIN       2 SSW OBRIEN            42.05N 123.71W
02/04/2017  M1.04 INCH       JOSEPHINE          OR   TRAINED SPOTTER

            RAINFALL SINCE MIDNIGHT. THE DURATION OF THE
            HEAVY RAIN EVENT WAS 10 HOURS.

&&

BS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
1037 AM PST SAT FEB 4 2017

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

0800 AM     HEAVY RAIN       2 SSE PISTOL RIVER      42.26N 124.39W
02/04/2017  M1.50 INCH       CURRY              OR   TRAINED SPOTTER

            . THE DURATION OF THE HEAVY RAIN EVENT WAS
            24 HOURS.

&&

BS