362
FXUS66 KMFR 160451
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
951 PM PDT Sat Jun 15 2024

.UPDATE...Updated the aviation and marine sections.

&&

.AVIATION...16/06Z TAFs...VFR is expected to remain the predominant
condition through Sunday evening. But, patches of stratus are
expected along northerly facing slopes, including the Umpqua Divide,
late tonight into early Sunday morning. The next front will move
across the area Sunday afternoon through Sunday night with skies
becoming cloudy and a slight chance to chance of showers, mainly in
Oregon. -DW

&&

.MARINE...Updated 830 PM Saturday, June 15, 2024...North winds
with a weak thermal trough will peak late this evening, building
steep seas south of Port Orford that will persist into Sunday
morning.

Relatively low, short period seas are expected later Sunday
into Sunday evening. Then, north winds strengthen late Sunday night
with steep seas expected south of Port Orford again, at least into
Tuesday morning, and possibly for much of the week.

The week will be filled with persistent north winds over the coastal
waters. Areas north of Cape Blanco are looking at north winds of 10
to 20 knots while south of Cape Blanco is looking at 15 to 25 knots.
Overall seas are expected to remain under 10 feet but areas south of
Port Orford is likely to see some steep wind driven wave action at
times due to the north winds approaching 25 knots. -Sargeant/DW

&&

.PREV DISCUSSION... /Issued 236 PM PDT Sat Jun 15 2024/

SHORT TERM...Through Tuesday morning...Scattered cloud cover
remains from a low pressure system passing to the north this
morning. While this system was mostly as unimpactful as expected,
the Roseburg Airport had 0.20 inches of rainfall today. Meanwhile,
a rain gauge about 3 miles west of the airport got 0.02 inches
while another gauge 3 miles to the east got 0.05 inches.

A cold air mass associated with the low pressure system will remain
over the area tonight, bringing below seasonal low temperatures
across the area. A Freeze Warning remains in place for Sunday from 1
AM to 8 AM for areas east of the Cascades for areas that will drop
to 32 degrees or below. Areas covered by this Watch include eastern
Klamath County, most of Lake County (Summer Lake and Adel are
forecast to be 3 to 4 degrees too warm), as well as parts of Modoc
and northeast Siskiyou County. Other areas east of the Cascades will
still see chilly temperatures, even if they don`t quite reach
freezing level. Sensitive plants and animals may require some
planning overnight.

The low pressure system will move away to the northeast during the
day Sunday, but a cutoff low will develop in its wake. That cutoff
will swing over east side areas, bringing slight (10-30%)
precipitation chances. Most of the measurable rainfall is expected
over Lake County, but some of those lower 10-15% chances are over
Klamath County as well as Mount Ashland and Mount Shasta. Amounts
are forecast to be light, with 0.15 inches possible over higher
elevation terrain in Lake County and less in other areas. Gusty
evening winds will cover wider areas east of the Cascades than
normal, but nothing approaches Advisory levels.

Sunday night will be chilly again as the cold air mass remains in
place. A Freeze Watch is in place for areas east of the Cascades
from late Sunday into early Monday morning, this time including more
areas of Modoc County. An upgrade to a Freeze Warning is likely,
but additional guidance will help to determine the best area for
the final product. Probabilistic NBM guidance had 20-50% chances
of freezing temperatures in Modoc and eastern Lake counties,
which isn`t generally enough confidence for a Warning this far
out. The absence or presence of cloud cover during the day could
further change expected nightime temperatures in this period.

With both the main and cutoff low off to the east, Monday will be a
transition from active to likely stable atmospheric conditions.
While west side valleys will warm up a few degrees from Sunday`s
daytime highs, temperatures across the area will remain below
seasonal norms. Monday night into Tuesday will remain cooler as
well, but the current forecast has a greatly reduced area of
freezing concerns. Forecast overnight temperatures of 32 degrees
or below are currently limited to the Chemult, Crescent, and Fort
Rock areas for Monday night into Tuesday morning. -TAD

LONG TERM...Tuesday through Saturday night.

Gusty breezes and cool temperatures continue Tuesday. But, the
spring-like weather will then come to an abrupt end. The outlook is
for a warming trend with dry and much warmer/hot weather inland for
the rest of the week. Meantime, northerly winds will result in
persistent night and morning coastal low clouds and patchy fog.

With that said, there are some minor model differences in the
strength of ridging that will affect the extent of heating, and more
importantly will make the difference between a stable air mass or a
weakly unstable air mass that would allow the introduction of
modest, slight chances of afternoon/evening thunderstorms over some
portion of the area. For now, the forecast reflects the large
majority of ensemble members, supporting a persistently stable air
mass.
-DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Freeze Warning from 1 AM to 8 AM PDT Sunday for ORZ029>031.

     Freeze Watch from late Sunday night through Monday morning for
     ORZ029>031.

CA...Freeze Warning from 1 AM to 8 AM PDT Sunday for CAZ084-085.

     Freeze Watch from late Sunday night through Monday morning for
     CAZ084-085.

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 PM Sunday to 5
     AM PDT Tuesday for PZZ356-376.

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

&&

$$