Area Forecast Discussion
Issued by NWS Medford, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS66 KMFR 191150

Area Forecast Discussion
National Weather Service Medford OR
350 AM PST Sun Feb 19 2017

.DISCUSSION...Deep low pressure over the northeast Pacific will
continue to usher in wet and windy weather at times to the region
through Tuesday. Thereafter through late week the weather will
turn colder as the trough migrates across the Pacific Northwest
and a cold northerly flow sets up.

The trough passing through this morning is accompanied by
unstable conditions over the coastal waters north of Cape Blanco
where several lightning strikes are being observed in cell
clusters moving onshore around Florence. Conditions will remain
similar there through the day with the instability moving off to
the north by evening. Meanwhile, moist onshore flow and ample
dynamics will provide widespread moderate shower activity inland
across the west side and Cascades. A winter weather advisory
continues through the morning with snow levels between 3000-3500
feet. 2 to 5 inches of additional accumulation looks likely today
across the Cascades and Siskiyous but precipitation rates will
taper off by afternoon as snow level rise in flow transitioning to

The GFS and ECMWF are somewhat similar in advertising a deep
surface low to move from south to north through the coastal waters
late tonight through Monday morning. A gale warning has been
issued for this event. In addition, high wind watches have been
issued for the Shasta Valley and Summer Lake areas as southwest
flow between 700-500 millibars increases to 60 to 85 kts.
Increasing precipitation rates will occur with heavy rain mainly
on tap for the coast through Josephine county and Siskiyou

Yet another short wave will roll through Monday night into early
Tuesday with a period of heavy rain and mountain snows. Will need
to watch the surface low forecast as the GFS is indicating another
fairly strong surface low to move up the coastal waters with a
potential high wind event. Not seeing a lot of agreement in the
operational solutions or ensembles so confidence is marginal at
this time. Despite the wind uncertainties, confidence on
precipitation amounts is pretty good.

The Scott River at Fort Jones and the Klamath River at Seiad
Valley are forecast to get close to flood stage by Tuesday morning.
A hydrologic Outlook is in effect for these areas and flood
watches may be required later this morning or this afternoon after
coordination with the River Forecast Center in Sacramento. Storm
total precipitation amounts from Curry through southern Josephine
and Siskiyou Counties will range from 2 to 6 inches from this
morning through Tuesday.

The pattern transitions to a cool and showery regime later in the
week with snow levels dipping to valley floors across the west
side Thursday through the weekend. Some low elevation snow
accumulations look possible, but details are fairly uncertain at
this time. Have knocked down some of the temperature forecasts in
this time frame several degrees.


.AVIATION...19/06Z TAF CYCLE...Areas of MVFR/IFR cigs with higher
terrain obscured will persist through Sunday morning with widespread
showers, breezy south winds, and freezing levels of around 3000 to
4000 feet above sea level. Late Sunday morning and into the
afternoon, expect conditions to improve somewhat mostly VFR with
areas of MVFR, and showers gradually decreasing in coverage and
intensity. -BPN


.MARINE...Updated 800 PM PST Saturday 18 February 2017...Winds
will become southerly ahead of a front that will move through the
waters tonight into Sunday morning. Winds will rise to very briefly
to near gales around midnight tonight. High long period swell will
build over the waters late Sunday. Two storms could impact the
waters Sunday night through Monday night with the potential for
gales and very steep seas before conditions improve toward


OR...Wind Advisory from 10 AM this morning to 10 PM PST Monday for
     Winter Weather Advisory until 1 PM PST this afternoon ABOVE 3000
     FEET for for ORZ025>028.

CA...Winter Weather Advisory until 1 PM PST this afternoon for
     Winter Weather Advisory until 1 PM PST this afternoon for
     Wind Advisory from 10 AM this morning to 4 PM PST Monday for

Pacific Coastal Waters...Small Craft Advisory until 7 AM PST Monday for
     Gale Warning from 7 AM to 4 PM PST Monday for
     Hazardous Seas Warning from 7 AM to 4 PM PST Monday for


MTS/MTS/SBN is the U.S. government's official web portal to all federal, state and local government web resources and services.