Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Medford or
353 am PDT Sat Oct 25 2014
Updated marine discussion.
Marine...updated 344 am PDT Sat 25 Oct 2014...strong surface low
pressure has moved inside 130w this morning and will move north
along the coast skirting the western edge of our waters. This puts
the strongest pressure gradients over our waters this morning into
early afternoon, and as a result, south winds will continue to
increase. Winds peak just as the low moves to our north late this
morning, with high end gales and storm force gusts over much of the
area. Seas will also be very steep and chaotic today. Winds shift to
the west and begin to diminish later this afternoon, but seas will
continue into the evening before subsiding. We'll see a relative
break in the storminess Sunday and Monday, but another front will
bring strong south winds and very steep seas Tuesday. More fronts
are expected through the week as this active pattern continues over
the northeast Pacific. -Wright
Previous discussion... /issued 321 am PDT Sat Oct 25 2014/
Discussion...low pressure is now moving inside of 130 west. Near the
center of the low there have been a few lightning strikes which
suggest there is plenty of energy with this. The models are in good
agreement tracking the low northeast just west of the Oregon coast
today, then moving inland near Grays Harbor Washington this evening.
This track is going to be favorable for moderate to strong winds for
most of the forecast area. Winds have been on the increase during
the overnight hours over most of the forecast area. This past hour
Wednesday had sustained wind at 36 miles per hour with gust to 52 miles per hour. It's blowing
pretty good at Ashland and it has picked up here recently at the
Airport. Expect winds to pick up in the Medford during the morning
and continue into this afternoon. The strongest winds will be east
of the Cascades near Summer Lake...Shasta Valley...mountains and
the southern end of the Rogue Valley. In fact models are
suggesting winds could reach warning criteria there and have
issued a High Wind Warning. Also south winds could mix down into
the Umpqua basin and have expanded the Wind Advisory to include
much of Douglas County. Details on these can be found at npwmfr.
In addition, to wind impacts, this strong low will bring rain to the
coast early this morning. In fact it's already pushing into the
South Coast. Precipitation will move inland today, but we'll
continue to get downslope in the Rogue Valley, so it's possible we
do not get anything measurable until late this afternoon. Cold air
aloft will push in immediately behind the front and associated
instability will bring a chance for thunderstorms with the best
chance at the coast this morning, then inland late this morning
through the afternoon. Of note is that any thunderstorms that occur
may bring strong gusty winds due to the strong winds aloft.
Precipitation amounts will be highest along the coast and coastal
mountains with 2-4 inches possible and up to 2 inches elsewhere in
Curry, Coos, Josephine and western Siskiyou County. Up to an inch is
possible along the Cascades and 0.25 to 0.50 of an inch elsewhere
west of the Cascades with most of that coming in tonight.
Post frontal Sowers will continue tonight into Sunday with most
showers expected to be along and west of the Cascades. Snow levels
will drop to around 5000 feet with 3-6 inches possible over the
higher elevations along the Cascades by Sunday morning. Winds will
also decrease tonight east of the Cascades and are not expected to
be a concern on Sunday.
Post frontal showers in a moist northwest flow continue Sunday
morning. 500 mb heights increase in the afternoon which should
result in decreasing showers from south to north. A break in the
weather is still expected Monday with dry conditions and milder
temperatures. Another front will impact the area Monday night into
Tuesday bringing another round of moderate to heavy precipitation to
the coast and coastal mountains. The GFS and European model (ecmwf) suggest the front
could stall Tuesday night through Wednesday before lifting north as
a warm front Wednesday night. -Petrucelli
Aviation...based on the 25/06z taf cycle...along the coast and in
the Umpqua basin...initially there will be areas of IFR ceilings with
local MVFR visibilities. Precipitation and strong winds will develop along
the coast later tonight and spread inland...and those areas will
lift to areas of MVFR ceilings with higher terrain obscured. Low level wind shear may
affect koth and krbg operations. Areas of IFR ceilings will return
Saturday evening. Over the remainder of the area...VFR ceilings will
prevail into Saturday...but higher terrain will become obscured.
Local MVFR ceilings will develop in the afternoon and evening...becoming
more widespread Saturday night. Strong winds will develop later
tonight...diminishing Saturday evening.
or...High Wind Warning until 11 PM PDT this evening for orz029>031.
High Wind Warning until 5 PM PDT this afternoon for orz021-022.
Wind Advisory until 5 PM PDT this afternoon for orz023.
High Wind Warning until 5 PM PDT this afternoon for orz028.
High Wind Warning until 5 PM PDT this afternoon for orz026.
California...High Wind Warning until 5 PM PDT this afternoon for caz082.
High Wind Warning until 5 PM PDT this afternoon for caz080.
High Wind Warning until 5 PM PDT this afternoon for caz081.
High Wind Warning until 11 PM PDT this evening for caz083-085.
Pacific coastal waters...Gale Warning until 2 PM PDT this afternoon for
Hazardous seas warning until 8 PM PDT this evening for