815
FXUS66 KMFR 052149
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
249 PM PDT Sun May 5 2024

.SHORT TERM...Through Wednesday morning...Upper flow aloft around a
low pressure system to the east of our area counties to bring
showery activity across northern California and southern Oregon. For
this afternoon, radar indicates that a wide area of showers remains
over Lake, Modoc, and eastern Klamath counties with generally
scattered showers elsewhere. This activity will decrease steadily
overnight, with 20-40% chances of showers remaining over the Coos
County coast and the Cascades through this evening.

Cold overnight temperatures remain in the forecast for Monday
morning. There is high confidence in the temperatures for the Shasta
and Scott valleys returning to at or below freezing tonight. A
Freeze Warning has been issued for these areas from 2 AM through 9
AM on Monday morning to communicate this expected hazard. Similar to
Sunday morning, the chance for near or at freezing temperatures in
the southern Rouge and Illinois valleys remains, but is slight (5-
10%) and is not enough to support additional warnings for those
areas.

A warm front will bring another round of activity on Monday, with
showers arriving on the Oregon coast in the early hours of the
morning and moving eastward through the day. Amounts look
inconsequential, with a quarter to half an inch of rain over coastal
areas and 2 to 6 inches of snow over the Cascades through Monday.
This front will also bring gusty winds, especially to areas east of
the Cascades. A Wind Advisory will be in effect on Monday from 11 AM
to 8 PM for northeast Lake County as gusts exceeding 40 mph are
expected in this area.

Post-frontal showers will continue over the Oregon coast and the
Cascades through the day Tuesday, but conditions look to be stable
otherwise. Temperatures will start to warm as the upper trough moves
away to the east. Afternoon gusty winds will be present east of the
Cascades again, but are not forecast to reach Advisory levels.
-TAD

.LONG TERM...Wednesday through Sunday night.
The boundary between the short term and the long term is very
appropriate today, with the the slow-moving trough exiting our
region, and broad high pressure centered offshore building in for an
extended stay. Lingering low level moisture is expected to produce
early morning stratus in Douglas and Josephine counties, including
Roseburg, Cave Junction, and Grants Pass. Otherwise, after another
chilly morning, a pronounced warming and drying trend will get
underway during Wednesday.

This warming will be most significant in southern Curry County with
a Chetco effect of downslope warming expected to produce highs in
the lower 70s for Brookings on Wednesday, lower 80s on Thursday, and
lower 70s into Friday morning before the low level flow turns
onshore. The peak of this warming trend at the coast is expected on
Thursday. Elsewhere, today`s highs at 20 to 25 degrees below normal,
in the lower 50s on the west side and lower 40s on the east side,
will seem a distant memory with Wednesday highs near normal at other
portions of our coast, and several degrees below normal for inland
sites. The warming will be kicked up a notch or two for the
remainder of the long term, Thursday through Sunday, with lows above
normal, and highs around 10 to 20 degrees above normal. The swing in
temperatures from this weekend to next weekend will be in excess of
30 degrees, with the peak of this very strong warming trend expected
at inland locations on Saturday.

A trough is likely to approach the area on Sunday, Day 7, with only
slight cooling.  The speed and position of this trough will be the
main determinants in whether a risk of showers and thunderstorms
develops on Sunday or holds off until Monday/Day 8.

&&

.AVIATION...05/18Z TAFs...The worst conditions today will be along
and east of the Cascade Crest as MVFR/IFR conditions can be expected
due to snow showers reducing visibility and from lower Ceilings.
Klamath Falls  and other areas east of the Cascades will have some
gusty west winds (up to 30 kt at times).

West of the Cascades, expect mostly a mix of VFR/MVFR, with MVFR
ceilings/visibilities most likely in heavier showers primarily along
the coast and in Douglas County. Area wide, higher terrain will
experience obscuration at times.

A lessening in shower activity is expected from 00z to 06z, before
another front moves onshore during the 06z TAF window. Gusty
southerly winds and renewed shower activity should be expected when
the front moves through.
-Miles

&&

.MARINE...Updated 130 AM Sunday, May 5, 2024...Fresh swell
dominates the sea state right now. Seas will become more chaotic as
another front moves through late tonight into early Monday morning.
The resulting southwest winds should build near, but remain under,
gale force. Moderate swell-dominated seas follow Monday into
Tuesday. A thermal trough will develop Tuesday afternoon with gusty
north winds and steep wind-driven seas, strongest south of Cape
Blanco. Wind speeds will peak late Wednesday, but strong northerly
winds will persist into Thursday night. The thermal trough will
weaken Friday into next weekend. -DW/Miles


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 11 AM to 8 PM PDT Monday for ORZ031.

CA...Freeze Warning from 2 AM to 9 AM PDT Monday for CAZ080-081.

PACIFIC COASTAL WATERS...Small Craft Advisory until 8 PM PDT Monday
     for PZZ350-356-370-376.

&&

$$

TAD/DW/MCB