993
FXUS66 KMFR 041537
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
837 AM PDT Sat May 4 2024

.DISCUSSION...Widespread rainfall continues across northern
California and southern Oregon as a low pressure system moves over
the area. Oregon highway webcams are showing snowfall and low
visibilities at higher elevations. Extra caution is advised for
anyone traveling through the Cascades and western Siskiyou County
today. Additional details can be found in a continuing Winter
Weather Advisory.

Please see the previous discussion for more details about the
short- and long-term forecasts. -TAD


&&

.AVIATION...04/12Z TAFs...Unfavorable flying conditions are
expected through at least 19Z as a potent frontal system moves
through. Widespread MVFR ceilings, terrain obscurations and periods
of moderate rain and mountain snow can be expected. Local IFR/LIFR
can occur as well, especially in times of heavier precip. Some wet
snow could even mix in with the rain briefly later this morning in
Klamath Falls. Precipitation behind the front will become more
showery this afternoon, but we still expect plenty of MVFR along
with areas of higher terrain obscured through this evening. Some
improvement to VFR tonight, though areas of MVFR will remain.
-Spilde

&&

.MARINE...Updated 820 AM Saturday, May 4, 2024...Moderate west
winds and fresh short period west swell will continue today. Rain
showers and a low chance of isolated thunderstorms are expected
today. Southwest winds increase Sunday ahead of another front that
will move through late Sunday night into Monday. This could bring
conditions hazardous to small craft. Seas are likely to remain
elevated Monday night into Tuesday with building west-northwest
swell. After that, we expect high pressure to build in mid-late next
week with a thermal trough strengthening along the coast. This will
bring a return of stronger north winds and steep seas, highest south
of Cape Blanco. -Spilde/Miles


&&

.PREV DISCUSSION... /Issued 401 AM PDT Sat May 4 2024/

DISCUSSION...RADAR is showing rainfall across most of southern
Oregon and northern California -- the dry areas include much of
Lake and Modoc Counties, but even those areas will begin to see
precipitation in the next few hours. This is part of a low
pressure system that is moving across our area. Precipitation
will remain somewhat steady into the late morning hours before
turning more showery in nature in the afternoon with thunderstorms
possible over a relatively large portion of our area.

The bigger issue at the moment is snow levels. While snow levels
are remaining somewhat high at the moment, they are expected to
crash relatively soon as the front continues to move inland. With
the heavier precipitation bands occurring as this happens, there
could be some sloppy conditions, especially in the Cascades and in
Western Siskiyou County, especially above 4000 feet. Will continue
the Winter Weather Advisories at this time.

In addition, winds are expected to pick up later this morning for
the higher terrain of Lake County to include the Winter Rim and
highway 31 between Summer Lake and Paisley. Will continue the wind
advisory for those locations as well.

Showers will continue overnight tonight as colder air filters in
behind a frontal boundary. This will lead to some freezing
temperatures for portions of western and central Siskiyou County
where confidence is high with a 90 percent of reaching freezing
temperatures in the Scott and Shasta Valleys. Have issued a freeze
warning for these areas for tomorrow night. In addition, portions
of the Applegate and the southern Illinois Valley might also reach
freezing, with a 40% chance. Statistical guidance is showing
temperatures a little warmer than freezing. Would like to see one
last model run before making a decision either way for these
areas.

Temperatures will begin to warm up over the next several days as
the low progresses eastward. Showers, however, will remain as
additional weak disturbances pass over the area with zonal (west
to east) flow. Widespread impacts from these showers are
generally not expected. Then, by midweek the pattern changes and a
ridge of high pressure returns. This ridge will help us warm up
and dry out into the weekend.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 11 PM PDT this evening above 4000
     feet for ORZ027-028.

     Wind Advisory until 5 PM PDT this afternoon for ORZ030-031.

CA...Winter Weather Advisory until 11 AM PDT this morning above 4000
     feet for CAZ080.

     Freeze Warning from 2 AM to 8 AM PDT Sunday for CAZ080-081.

PACIFIC COASTAL WATERS...None.

&&

$$