Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Medford or
419 PM PDT Sat Oct 25 2014
Short term...tonight through Tuesday night.
The area was impacted by the one-two punch of a cold front early this
morning and a trailing surface trough that has reached the
Cascades and will continue across the east side this evening. The
most notable impacts were due to strong winds and large waves at
the shore. The Cape Blanco buoy(buoy 15) had seas reported at 26
feet and at least one rogue wave with a height of 46 feet.
Winds have diminished behind the surface trough and will continue
to do so tonight. Notable peak wind gusts include 94 miles per hour at Cape
Blanco, 105 miles per hour at Squaw Peak in the Siskiyou Mountains of
southern Jackson County, 44 miles per hour in Medford, 61 miles per hour at Weed, and 53
miles per hour at Summer Lake.
Also, areas of moderate to heavy rain are continuing, but that is
beneficial. There has been a thunderstorm near Highway 66 into
extreme southwest Klamath County and another near Grass Lake in
Siskiyou County. Isolated thunderstorms are possible across much
of the east side early this evening. These thunderstorms and the
heaviest bands of rain are occurring with the surface trough.
Numerous Post-frontal showers are expected this evening with
activity gradually diminishing late tonight before ending
completely early Sunday evening. Snow levels will be dropping from
around 7500 feet now to a shade under 5000 feet by sunrise on
Sunday morning. Tonight through Sunday morning...snow showers of
up to a few inches are expected over the higher terrain with the
greatest accumulation on west facing slopes...especially the
vicinity of Crater Lake. Sunday will be cool and showery with some
breaks in the clouds...especially during the afternoon and on the
east side. The snow level will rise marginally to around 5000 to
5500 feet but there will not be many flurries lingering during
The air mass will stabilize Sunday night which is likely to lead
to areas of west side low clouds and valley fog to start out
Monday morning. The models are in good agreement with weak ridging
building into the area on Monday while the remnants of Tropical
Storm Ana (which earlier brushed past the vicinity of hawaii) move
toward the Washington coast. Clouds will increase in our area
Monday night with rain expected to develop at the southern Oregon
coast around midnight. The GFS and European model (ecmwf) are in good agreement on
the timing and have both trended slightly weaker/less wet with
rainfall amounts but the southern end of the system is still
likely to produce light to moderate rain for the west
side...except heavy rain in the mountains of Curry County Tuesday
through Tuesday night. The east side probability of precipitation will be mainly in the
category of a chance of light rain.
Long term...from Wednesday morning though Saturday.
Models are in very good agreement for pretty much all of the
extended periods. The trailing remnants of Ana are feeding into
the Pacific northwest with the latest runs showing the jet farther
south...yesterday the jet axis was over Seattle and today it is
showing it over the mouth of the Columbia. This still places the
jet support well north of the region and the greatest contributing
factor to heavy rain being low level convergence and orographic lift
with the onshore component of the low level flow.
The weak upper level ridge over the region shifts east ahead of
the next approaching system moving in with a deepening upper level
trough offshore on Thursday. This system has much more dynamic
support with an almost kissing jet pattern indicated as the right exit
region of a southerly jet combines with the nose of a 110 knots jet
from the southwest. This will also combine with good low level
convergence and orographic lift to bring another round of heavy
rain to the region. Models remain in good agreement with an active
showery pattern remaining into next weekend. /Sven
Aviation...for the 25/18z taf cycle...the front has moved out the
east side but a secondary trough is still bringing strong southerly
winds tot he east side with diminishing winds on the west side as
the trough is moving inland. IFR conditions should remain in the
coastal waters and on the coast with MVFR conditions moving for most
of the west side later this evening. Sven
Marine...updated 345 PM PDT Sat 25 Oct 2014...the strong surface
low responsible for gales and heavy seas is moving off to the
northeast. Winds have already turned westerly and are beginning to
diminish. Gales are expected to continue through the afternoon
mainly in the vicinity of Cape Blanco and north. Winds should
diminish below gale criteria by the evening. Although winds will
improve, heavy seas are expected to continue overnight into
Sunday. There will be a break between systems later Sunday
lasting through Monday evening before another front brings the
return of strong southerly winds. This active pattern is expected
to continue through the week. /Mnd
or...High Wind Warning until 11 PM PDT this evening for orz029>031.
High Wind Warning until 5 PM PDT this afternoon for orz028.
California...High Wind Warning until 5 PM PDT this afternoon for caz082.
High Wind Warning until 11 PM PDT this evening for caz083-085.
Pacific coastal waters...Small Craft Advisory for winds until 11 PM
PDT this evening for pzz350.
Small Craft Advisory for hazardous seas from 8 PM this evening
to 5 PM PDT Sunday for pzz350-356-370-376.
Gale Warning until 5 PM PDT this afternoon for pzz350-356-376.
Hazardous seas warning until 8 PM PDT this evening for
Small Craft Advisory for winds until 11 PM PDT this evening for
Gale Warning until 8 PM PDT this evening for pzz370.
Hazardous seas warning until 11 PM PDT this evening for pzz370.