Flood in California, February 10, 2017

Area Forecast Discussion
National Weather Service Medford OR
833 PM PST Thu Feb 9 2017

.SHORT TERM...Tonight, rainfall is decreasing over the area with
mainly lighter showers behind a front. Heavy rainfall that fell
over portions of the area and rain combined with snow melt has
resulted in elevated river flows and several rivers in flood.
River flood warnings remain in effect for portions of the
Coquille, South Fork Coquille, Sprague, Klamath, Scott, and Pit
rivers. Please see the FLSMFR for details. Models continue to show
that a weak front and upper trough will move into the area on
Friday bringing additional showers. Widespread showers are
expected from the Cascades west. East of the Cascades, shower
activity may be more scattered. Shower activity will peak tonight
into Friday morning along the coast and Friday morning into
Friday afternoon for inland areas. High snow levels will lower
tonight and Friday, lowering down to between 3500 to 4500 feet
elevation for most areas by Friday morning. Higher snow levels of
around 5000 feet may persist into Friday afternoon for some east
side areas, such as in Lake and Modoc counties.

On the weekend, dry weather is likely with models showing an
upper ridge developing over the region. This dry pattern may
continue early next week into Monday and Tuesday.

&&

.AVIATION...10/00Z TAF CYCLE...A frontal system is moving well east
of the Cascades this evening. Winds are still gusty along the
coast and over the east side, but are easing across most of the
rest of the area. Even so, turbulence could still be an issue
for the next several hours. Overall, expect a mix of MVFR and VFR
with showers and terrain obscured tonight. Showers should diminish
in coverage overnight, but another front will move onshore Friday
morning bringing more widespread showers into afternoon. Conditions
will once again vary from VFR to MVFR with mountain obscurations
likely. -Spilde

&&

.MARINE...Updated 300 PM PST Thursday 9 February 2017...Winds have
veerED to southwest and subsideD to advisory strength in most areas
this afternoon. Low pressure moving northeast toward Washington will
bring an increase in winds tonight with occasional gale force gusts
into early Friday morning...mainly north of Cape Blanco and beyond
20 NM from shore. Seas will remain high and very steep into Friday
then will ease below 10 feet but remain rather steep this weekend.
Overall, expect light to moderate northerly winds this weekend into
early next week. The next cold front has the potential for gales on
Wednesday with seas becoming high again. -Spilde

&&

.PREV DISCUSSION... /Issued 353 PM PST Thu Feb 9 2017/

SHORT TERM...

The mature low off shore continues to weaken as shown my pressure
gradients from major airports in the region. The Medford and
Redding pressure gradient has diminished down to 3 from 8 earlier
this morning. Still kept the wind warning in the Cascades out to
0z because the front is a little slower than expected. Squaw peak
is still gusting to 60mph, so the westward facing Cascades should
still see some of the strong elevated winds ahead of the front.
Eventually later this evening, these winds should continue to
diminish as the low continues to weaken.

As the front pushes further onshore and eventually diminishes,
post frontal showers and rain will continue along the coast and
for some inland areas. The upper level energy aloft will then
drift south and pull up some more moisture for Friday giving us
additional rainfall at the coast and along the Cascades primarily.
As cooler temperatures move inland, we are expecting snow along
the Cascade range during Friday. Some of the snow fall totals from
5000 to 7000 feet will be around 6 inches over 18 hours, which is
right on the cusp of winter weather advisory criteria.

As for additional flooding, it looks like the bulk of the heavy
rain is over for most of the inland areas. We're expecting more
rain along the coast and near the Brookings area into Friday with
no major impacts expected. As the trough to the south passes late
Friday evening, high pressure will gradually begin to build into
the weekend bringing rather pleasant weather.

The only other mention left is fog with dewpoints currently
sitting at 52 degrees in Medford. If we get a little bit of
clearing tonight and calm enough winds, some patchy fog is
possible. Didn't add it to the weather grids right now as
confident was a little to low.

CZS

LONG TERM...(Monday through Thursday)...Strong ridging will
maintain dry weather across the forecast area Monday and Tuesday
although by Tuesday mid and high level clouds will be spreading into
the area. The coastal waters could see light rain ahead of the next
system. Both the ECMWF and the GFS are close in timing and bring the
next front inside 130W Tuesday night. Rain chance increases across
the west side of the Cascades Wednesday, and by Thursday both models
spread precipitation into all of our forecast area. Snow levels
during these two days will be in the 6500-7000 foot range but are
expected to lower 5000-6000 foot range Thursday night. The pattern
looks wet beyond Thursday with the snow levels falling to around 400
feet next weekend. /FB

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

Pacific Coastal Waters...Hazardous Seas Warning until 4 PM PST Friday for
     PZZ350-356-370-376.
     Gale Warning until 7 AM PST Friday for PZZ370.

CC