Area Forecast Discussion
Issued by NWS Medford, OR
FXUS66 KMFR 270300
Area Forecast Discussion
National Weather Service Medford OR
800 PM PDT THU MAY 26 2016
.DISCUSSION...27/00Z NAM in.
Marine stratus persists over the coastal waters and the Umpqua
Basin. Over the remainder of the Medford CWA mostly clear skies
prevail...except for some east side stratocumulus that will either
dissipate or move out of the area in the next few hours. The
marine inversion is high enough to allow some of the marine stratus
to move over some of the remaining west side valleys later tonight.
The models continue to to trend north with the storm track...and
now the Medford CWA is forecast to remain completely south of it
from Saturday on.
Between now and then two more short waves will move through...one
late tonight and another Friday afternoon. The associated fronts
will be quite weak and little in the way of precipitation is
expected other than some drizzle along the coast and in the Umpqua
Basin. It will bring an onshore marine push to the area Friday so
there may be some increased cloud cover over the remainder of the
west side and some gusty winds in the afternoon. Inland highs will
be around 5 degrees below normal.
Mostly clear skies will make for some cold temperatures east of
the Cascades and a Freeze Warning remains in effect for the
Klamath Basin. Saturday morning still looks to be the coldest one
of the string...so it will freeze there Saturday morning as well.
Flow aloft will turn from northwest to west Saturday and stay that
way through Sunday. Expect mostly clear skies except in the areas
affected by marine stratus. Saturday highs will be near normal
over most of the area and Sunday highs will be around 5 degrees
above normal. The warming trend will continue into the extended
Long Term discussion from the Thursday afternoon AFD. Monday
through Thursday Night...Upper level ridging will be in control of
the area throughout much of the extended term. As typical of the
warmer season, thermal troughing will develop to our south, and
this will produce an extended period of offshore easterly flow.
Monday will be the warmest day at the coast, then when the trough
shifts inland, temperatures there will cool Tuesday into
Wednesday. Inland, warming will continue, with the warmest day
likely to be Tuesday or perhaps Wednesday before slight cooling by
the end of the term. Thursday, a large scale trough over the
eastern Pacific will approach the West Coast, shifting winds to a
more onshore southwesterly flow.
This pattern usually results in a dry period. However, models
solutions are showing a weak shortwave within the upper level flow
during the afternoon Wednesday, and this may be enough to produce
some convection along and west of the Cascades. Have introduced a
slight chance for afternoon and evening thunderstorms to cover this
thinking. Thunderstorms and showers are also possible Thursday
afternoon under a similar pattern, although the focus should be
slightly closer to the coast. Confidence in convection both days is
low, but should increase if models continue with this trend over the
next several runs. -BPN
.AVIATION...For the 27/00Z TAF cycle...High pressure and
nocturnal cooling will cause winds to turn a bit northeasterly
tonight through early friday along the coast and into the Umpqua
Basin. This net flow toward offshore areas should keep coastal
areas mostly vfr. In the Umpqua Basin mvfr is expected in the
06z-18z time frame, with moderate confidence that Roseburg will
be affected during a portion of this time period. Radiational
cooling is likely to again result in some patchy fog around
sunrise in portions of the upper Klamath Basin. All areas should
see mostly clear skies by noon local time. BTL
.MARINE...Updated 515 PM PDT Thu 26 May 2016...Strengthening high
pressure over the eastern Pacific and low pressure inland is
bringing strong north winds and steep to very steep seas to most
of the coastal waters area south of Cape Blanco. These winds will
peak this evening with Gale and Hazardous Seas Warning conditions
for a portion of the area south of Cape Sebastian. This pattern
will remain in place through the holiday weekend with steep seas
continuing south of Cape Blanco, but winds will be slightly weaker
It should be noted that nearly all of the current sea state now
and through the weekend is and will be comprised of wind wave and
very fresh swell. Thus, while seas are fairly steep in all areas,
they are only 3-6 feet north of Cape Blanco. We expect similar sea
conditions Friday as compared to today. On Saturday winds will
diminish and the strongest winds and highest seas will shift a bit
more west of the coast. Additionally, conditions are expected to
fall below warning levels to advisories south of Cape Blanco for
Saturday and Sunday with no advisories expected north of the Cape
after Friday evening. Numerical models do generally indicate winds
and seas will ramp upward again from the north Sunday and Monday in
the southern coastal waters area beyond 5 nautical miles of the
OR...Freeze Watch from late Friday night through Saturday morning for
Freeze Warning from 3 AM to 8 AM PDT Friday for ORZ029.
CA...Freeze Watch from late Friday night through Saturday morning for
Freeze Warning from 3 AM to 8 AM PDT Friday for CAZ084.
Pacific Coastal Waters...Small Craft Advisory for hazardous seas until
11 PM PDT Friday for PZZ350-356-370-376.
Small Craft Advisory until 11 PM PDT Sunday for PZZ356-376.
Gale Warning until 11 PM PDT this evening for PZZ356-376.
Hazardous Seas Warning until 11 PM PDT Friday for PZZ356-376.