High Wind in Oregon, May 28 to 29, 2022

Area Forecast Discussion
National Weather Service Medford OR
506 PM PDT Sat May 28 2022

Updated AVIATION Section

.DISCUSSION...

.Short Term...Rest of today through Monday Night (5/30)...An
abnormally cool and wet Memorial Day weekend continues for
southern Oregon and far northern California. A broad upper level
trough is currently drifting just of the coast of British
Columbia, and a strong shortwave orbiting this trough is producing
a vigorous late season storm to periods of rain and wind to the
forecast area today.

A surface low offshore has deepened today as it approaches the
central Oregon coast, where it will move onshore later this
evening and tonight. Gusty winds have preceded the front over the
coastal waters and along the coast itself. As is typical with
systems of this type (although the type is more typical to winter
and early spring than late May) winds over high terrain and across
the East Side will be gusty through tonight, especially in the
more exposed and wind-prone areas. A Wind Advisory remains in
effect for these areas.

Model guidance today, particularly the higher res suites, are
depicting a stronger burst of winds along the north coast (areas
north of Coos Bay) this evening as the compact surface low moves
onshore. With model winds at 925 mb of 50 to 60 kts, wind gusts
along the shore and just inland north of Cape Blanco are likely
to be much higher than earlier thought. This "stinger," highly
unusual for this time of year, has good potential to produce
numerous problems, especially for any campers or other outdoor
recreationists attempting to enjoy the holiday weekend. Also, with
trees now fully leafed, the likelihood for downed trees/branches
and power outages are increased. Given the much increased risk,
have issued a High Wind Warning for the immediate coast, and a
Wind Advisory for the coastal ranges, both within Coos and western
Douglas counties. For more details on this and the previously
mentioned advisory, see PDXNPWMFR.

Otherwise, this event will be primarily a rain producer, with
decent, but not strong, onshore moisture flow and plenty of
upslope production along the coast, the coastal ranges, and
especially the north Cascades. Up to an inch to an inch and a
half of precipitation is expected along the coast and coastal
ranges, as well as the Cascades and western Cascade slopes, with
other areas expecting around a quarter to half an inch, or even
less in the usual downsloping locations of the Rogue and Shasta
valleys. As it is May, thunderstorms will be a concern for most of
the region throughout the afternoon and evening, so even if there
are people who are willing to brave the rain and wind to enjoy
outdoor activities, lighting will be a threat, especially along
and east of the Interstate 5 corridor.

Snow levels will lower sharply behind the front, dropping to 4500
feet by this evening as the front passes and cooler air begins to
move into the region. With vigorous shower activity continuing
well into Sunday morning, this could result in several inches of
new snow for the Cascades, particularly along and north of Crater
Lake. While total snow amounts should remain below 6 inches for
the more well-traveled and populated areas, it is the holiday
weekend, and folks may be trying to hike or camp, or boat in the
area lakes, thus a Winter Weather Advisory was issued, with
details found at PDXWSWMFR. It is worthwhile noting that the
higher peaks could receive up to a foot of snow through Sunday
morning.

Sunday into Sunday night, we will see continuing showers and much
cooler, well below normal temperatures, more on the order of
early March than late May. Shower activity should taper off a bit
as the day goes on, with overall precipitation amounts trending
more towards the lighter side. The upper level trough responsible
for all of this unseasonable weather will finally dig south,
filling as it passes overhead Sunday night, brining most of, but
not all, precipitation chances to an end by Monday morning. A few
showers may linger in Coos and Douglas counties through Monday
afternoon as onshore flow continues, but otherwise the area will
see temperatures increase by about 10 degrees over those of
Sunday, with clearing skies through Monday night. -BPN

Long Term...Tue 31 May through Sat 04 June 2022...The extended
period will begin with a strong long wave ridge offshore and a
trough over the intermountain states. The Medford forecast area
will be under weakening northwest flow between these two features.

Tuesday through Wednesday look to be dry with a warming trend as the
ridge moves toward the west coast. The ridge will weaken as it moves
onshore.

The ridge axis will break to the east of the area Wednesday. This
will drive the thermal trough near the coast inland, and Wednesday
looks to be the hottest day of the coming week.

Flow aloft will turn southwesterly. A series of weak disturbances
ejecting from an offshore trough will move through Thursday into
Saturday, but none of these look to be big precipitation generators.
The main concern Thursday will be the possibility of thunderstorms,
as there will still be surface heating, some moisture will be
introduced to the air mass, and there will be weak upper level
forcing. Otherwise, mostly light shower activity is expected.
Temperature wise, a cooling trend will be in place Thursday through
Saturday.

&&

.AVIATION...29/00Z TAFs...A frontal system will continue to move
east of the Cascades this evening. There have been showers and
isolated thunderstorms accompanying this front along with
occasional MVFR ceilings/vis in heavier showers. Gusty winds will
also be an impact with most terminals seeing gusts in the 20-30kt
range into this evening. Some turbulence can be expected on
arrivals/departures. Peak gusts of 35-45kt are possible in some
areas, but highest risk is along the coast and east of the Cascades.
These winds will ease somewhat overnight into Sunday morning, but
will persist over the East Side.

Low pressure will bring an area of enhanced precipitation, lower
ceilings/vis (MVFR/IFR) and wind this evening from the coast to
Douglas County, including North Bend and Roseburg. But, this area
should largely skirt by to the northeast of Medford, getting wrung
out over the Cascades/adjacent foothills overnight into Sunday
morning. Freezing levels will drop to around 5000 feet and this will
lead to widespread snow and terrain obscuration near the Cascades,
mainly from Lake of the Woods northward. -Spilde

&&

.MARINE...Updated 200 PM PDT Saturday 28 May 2022...A potent
late season storm is bringing southerly gales north of Cape Blanco
with very steep and hazardous seas across all areas. Winds will
quickly shift to northwest late this afternoon, and a burst of
strong northwest winds is expected north of Cape Arago into this
evening. High end gales are likely with this burst, and wind gusts
could approach storm force at times. A high and very steep west-
northwest fresh swell peaking at 12 to 18 feet at 10 seconds is also
expected this evening and overnight. Winds diminish overnight, but
seas will remain very steep and hazardous through Sunday morning.

Winds and seas will diminish briefly Sunday afternoon into Monday,
then a developing thermal trough will bring gusty north winds and
steep wind driven seas to the area Monday evening through Tuesday
night, especially south of Cape Blanco. The thermal trough will
weaken Wednesday, and winds and seas will also diminish at that
time. /BR-y

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 2 AM PDT Sunday for ORZ029>031.
     Wind Advisory from 6 PM this evening to 1 AM PDT Sunday for
     ORZ023.
     Winter Weather Advisory from 8 PM this evening to 11 AM PDT
     Sunday for ORZ027.
     High Wind Warning from 6 PM this evening to 1 AM PDT Sunday for
     ORZ021.

CA...Wind Advisory until 2 AM PDT Sunday for CAZ084-085.

Pacific Coastal Waters...
     Gale Warning until 5 AM PDT Sunday for PZZ350-370.
     Hazardous Seas Warning until 5 AM PDT Sunday for PZZ356-376.