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000
FXUS66 KMFR 141754
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1054 AM PDT Sun Apr 14 2024

.UPDATE...UPDATED AVIATION SECTION

.AVIATION...14/18Z TAFs...Plenty of stratiform rain remains on the
radar scope this morning with a a mixture of ceilings in MVFR and
VFR ranges. The upper level low will continue to bring showers to
most of the TAF sites this morning with VFR ceilings most likely,
although periods of MVFR are in the forecast near Roseburg(KRBG) and
North Bend(KOTH). The atmosphere still has some potential
instability and lightning will be possible. There is a 40% chance
of more cloud to ground lightning in Lake County later this
afternoon with a 20-30% chance expanding to eastern Klamath
County.

Eventually, this low will start to move east this evening and the
shower activity will be on the downtrend. VFR ceilings remain most
likely with some MVFR ceilings east of the Cascades. There is also
the low potential of fog in the valleys given dew points in the
upper 40s. However, the statistical guidance is not as excited about
fog development Sunday night as probabilities are maxing at ~40% for
fog west of the Cascades.

-Smith/Hermansen

&&

.PREV DISCUSSION... /Issued 517 AM PDT Sun Apr 14 2024/

DISCUSSION...The main change this morning was to extend the
Winter Weather Advisory that is in effect for a significant
portion of Siskiyou and Modoc counties by a few hours, through the
early afternoon. It is in effect for western and south central
portions of Siskiyou County above 4000 feet, and for eastern
Siskiyou County and Modoc County above 4500 feet. An accumulation
is apparent at Snowmans Summit already this morning, and will also
accumulate at elevations as low as 3500 feet early this morning.
Accumulations will be most significant for southern portions of
Siskiyou and Modoc counties. Heating of the day is expected to
modestly increase snow levels. Normally, the coldest air is in the
far northern portion of our area, but snow levels will be lowest
in the far southern portion of our area...in the vicinity of a
closed upper level low.

The cold upper level low pressure over northern California will
move into Nevada today. This will continue rain and snow over the
area today with a slight chance of thunderstorms in south central
Oregon, focused upon the Winter Rim area, and secondarily, more
broadly across northeast Klamath and northern Lake counties.

Precipitation will gradually end from west to east across our area from
this afternoon into early Monday morning. Roughly, ending at the
coast by this afternoon, at the Cascade crest by this evening,
Highway 97 and the Klamath Basin around 7 PM, then lastly over
the Warner Mountains by sunrise Monday. Lingering low level
moisture will result in areas of valley stratus on Monday morning,
and a trend of gradually lesser amounts from day-to-day on
Tuesday morning into Thursday morning. This will result in
freezing morning lows for the east side and many of the normally
coldest west side valleys (including the vicinities of Cave
Junction, eastern Douglas County, and the Shasta Valley near
Yreka.

Dry weather with a warming trend of above normal afternoon highs
will follow Monday into Friday, with our region in a seasonably
typical pattern between low pressure north and east of our region,
and high pressure extending from the eastern Pacific into
California.

Model agreement is very good into Friday. A weak front is
possible late in the week. The blended model solution was utilized
to include a slight chance to chance of mainly west side showers
late Friday into Saturday. Looking at the situation another way, a
majority of ensemble model solutions do indicate a weak,
dissipating front which would result in little more than a slight
cooling trend and a modest increase in mid and upper level cloud
cover. The outlook favors continued dry and warm conditions during
day 8 through 10.

MARINE...Updated 500 AM Sunday, April 15, 2024...Low pressure
will continue affecting the region through Sunday, bringing gusty
northwest winds to the waters. These gusty winds combined with a
westerly swell will maintain steep seas with conditions hazardous to
small craft for all areas beyond 5 nm from shore through the weekend.

Conditions improve briefly by Monday morning as the upper low moves
further south and atmospheric stability builds. Improved conditions
will be short lived, however, as a thermal trough develops on Monday
afternoon and could remain in place through midweek or longer. This
pattern would bring another round of gusty north winds, along with
steep to very steep seas, especially south of Cape Blanco by Monday
afternoon. These conditions will likely be hazardous to smaller
Crafts during Monday afternoon and evening.

-Smith/BR-y

&&

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

CA...Winter Weather Advisory until 2 PM PDT this afternoon above 4000
     feet for CAZ080-082.

     Winter Weather Advisory until 2 PM PDT this afternoon above 4500
     feet for CAZ083-085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 AM PDT Monday
     for PZZ350-356-370-376.

     Small Craft Advisory from 2 PM Monday to 2 AM PDT Tuesday for
     PZZ356-376.

&&

$$