Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Medford or
810 am PST sun Mar 1 2015
Discussion...01/12z NAM/GFS in.
Mostly clear skies prevail across the Medford County Warning Area this morning
with moderate offshore low level flow. The exception is patchy fog
in the Coquille...Umpqua...and Illinois valleys. There is also
some low clouds around Grants Pass. Those areas will clear later
It is difficult to determine a wave number around the hemisphere
this morning but it doesn't appear to be a factor with an Omega
block in place over the eastern Pacific. The coldest air remains
over northeast and far northern Canada.
A strong ridge remains in place along 135w and it isn't going
anywhere anytime soon. The anchor lows for The Block are currently
over California and out near 40n 160w. Currently there is dry
northeast flow aloft over the area. All of this supports the dry
offshore low level flow pattern.
However...a strong short wave will move down the frontside of the
ridge tonight into Monday...and this wave does spend some time
over the water...so it may bring some precipitation to the area
along the coast and over the coastal waters tonight into Monday.
After that...offshore low level flow and dry weather will return
to the area Monday night. The ridge will gradually weaken in
place through Thursday...so the offshore flow will weaken as well.
Eventually some high level moisture will make it over the ridge
and over the County Warning Area around the middle of the week...but no additional
precipitation is expected.
Extended discussion from the early Sunday morning afd...the
models remain in good agreement showing the upper ridge near 130 west
shifting east over the Pacific northwest the latter part of the week and
remaining there through next weekend. Confidence is high we'll
remain flat out dry with temperatures above normal in the
afternoon. Nights will be cool, but they will trend higher later
in the week into next weekend. -Petrucelli
Aviation...for the 01/12z taf cycle...VFR conditions with
mostly clear skies will prevail through this evening. Late tonight
into Monday morning, a weak low will move south with increasing
clouds for the area. Skies will mainly remain VFR but near the coast
areas of MVFR ceilings with a chance of light rain are expected after
Marine...updated 0500 PST Sunday 1 Mar 2015...there is high
confidence that moderate northerly winds will persist through
Wednesday and will be strongest in the outer waters south of Cape
Blanco. A thermal trough along the coast and high pressure
offshore today will be followed by a low with light rain late
tonight into Monday morning. The pattern of a thermal trough at
the coast and high pressure offshore will develop again later
Monday and continue through Wednesday. The 00z GFS and European model (ecmwf) now
indicate that winds over the waters will remain northerly but
weaken late in the week as the high builds east. /Dw
Pacific coastal waters...Small Craft Advisory for winds from 1 PM
this afternoon to 10 PM PST this evening for pzz356.
Small Craft Advisory for hazardous seas until 10 PM PST
Monday for pzz350-356-370.
Small Craft Advisory for winds until 1 PM PST this afternoon
Small Craft Advisory for winds from 10 PM this evening to
10 PM PST Monday for pzz370.
Small Craft Advisory for winds until 4 am PST Tuesday
Small Craft Advisory for hazardous seas until 4 am PST
Tuesday for pzz376.