199
FXUS66 KMFR 140549
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1049 PM PDT Thu Jun 13 2024

Updated AVIATION Section

.SHORT TERM...Thursday afternoon into Saturday evening...An upper
ridge remains influential for current conditions this afternoon,
with continuing clear skies and above seasonal daytime highs for
inland northern California and southern Oregon. Temperatures along
the Oregon coast as well as the Umpqua and Illinois valleys will
be a little cooler than other areas.

Friday will see zonal flow aloft ahead of a pattern change over the
weekend. Patchy fog will be possible Friday morning over parts on
inland Coos county and the northern Umpqua basin. Daytime
temperatures will be near seasonal averages, and a shortwave will
bring periods of cloud cover Friday afternoon and evening. Low
temperatures across areas east of the Cascades will approach frost
concerns on Friday night into Saturday morning. Temperatures in
northern Klamath County look to be in the low 30s, with mid 30s
expected for southern Klamath and northern Lake counties. While this
isn`t a huge hazard given the dry conditions, these low temperatures
can be harmful to animals or vegetation.

The first and weaker of two weekend troughs will pass over the area
on Saturday morning. The main effect of this trough will be
supporting below seasonal temperatures during the day. Modest
precipitation chances (20-40%) will be limited to northern
portions of Coos and Douglas counties. Any rain that does manage
to fall will be measured in the hundreths of inches, at most. -TAD

.LONG TERM...Models are showing the potential for a wet and cool
period Sunday and Monday  with another low pressure center and
frontal system approaching the area Saturday night and moving into
the area from the west Sunday and Monday. This is followed a trend
towards warmer and drier weather Wednesday and Thursday.

Ahead of the low on Sunday, expect cool air to be in place. The
National Blend of Models supports overnight temperatures (Saturday
night and early Sunday morning) in the lower to mid 30s east of the
Cascades. This along with mainly clear skies would bring frost to
these areas. However, the track and timing of the frontal system
moving into the area will be a factor, especially in whether cloud
cover moves overhead. Cloud cover would result in slightly warmer
temperatures Saturday night and early Sunday morning.

Then, models and ensembles are favoring the low pressure system
moving into the region on Sunday and Monday. The track and timing on
this low is still uncertain. The variability in the strength and
track of the low as it moves inland, ranging from southern/central
Oregon to central California, will play a role in whether southern
Oregon and northern California see widespread precipitation or more
limited areas of showers. With an overall colder air mass in place,
expect temperatures below normal Sunday and Monday, as well as lower
snow levels (around 4500 to 6500 feet). These snow levels combined
with precipitation may result in some light snow in the mountains
but expect limited accumulation, except potentially at higher peaks.
Gusty winds late Sunday and Monday will be a potential as well,
especially for areas east of the Cascades and in the Shasta Valley.
Stronger winds are expected if the low tracks into southern Oregon
versus further south. Current models support winds gusting to 25 to
35 mph with a 10 to 15% chance for winds to gust to 40 mph.

The upper low is expected to gradually move eastward Monday night
into Tuesday. Late Tuesday through Thursday, models indicate weak
trough to near zonal flow over the region with a high pressure ridge
offshore. With this pattern expect temperatures to trend warmer and
mainly dry conditions.

&&

.AVIATION...14/06Z TAFs...MVFR ceilings are affecting the coast
north of Cape Blanco, including North Bend, this evening. Expect
MVFR to prevail there tonight, though ceilings could go back and
forth from MVFR to VFR (SCT) at times. Local IFR is possible closer
to sunrise and some IFR/LIFR could also develop along the south
coast near Brookings. The lower conditions should go back to VFR by
late morning. Inland, expect VFR to prevail the next 24 hours,
though there will be a fair amount of high cirrus Friday compared to
today. Winds won`t be as gusty in Roseburg or North Bend on Friday
(compared to Thursday). However, gusty (mostly NNW) breezes will
develop Friday afternoon at Medford and Klamath Falls with peak
gusts of 20-25 kt and 25-30 kt, respectively. Low ceilings probably
return to coastal areas Friday evening and some lower ceilings could
bank up against north and west-facing terrain then as well. -Spilde

&&

.MARINE...Updated 830 PM Thursday, June 13, 2024...North winds
and steep seas will linger overnight, highest south of Cape Blanco.
The small craft advisory north of Cape Blanco has been cancelled.
Conditions will improve Friday, especially north of Cape Blanco, as
a cold front approaches. The front passes on Friday night. A thermal
trough over northern California may produce advisory strength north
winds near shore south of Gold Beach Saturday afternoon and evening.

By Sunday, there is a lot of uncertainty with model guidance, and
there is the potential for a strong low to pass later Sunday into
Monday. This could bring in a strong fresh swell in addition to
stronger wind speeds than we currently have forecast. We essentially
have a scenario where either an upper level low takes a northern
track or a southern track through the region. As the track becomes
clearer, we should have a much better idea of potential hazards (or
lack thereof) early next week. -DW/Spilde

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this
     evening for PZZ350-370.

Small Craft Advisory until 8 AM PDT Friday for PZZ356-376.

&&

$$

TAD/CC/DW/MAS