253
FXUS66 KMFR 021550
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
850 AM PDT Thu May 2 2024

.UPDATE...The main belt of precipitation within the area today
lies just south of the ORegon/California state line, with
scattered showers across the rest of the area. This precipitation
will continue to move to the southeast and dissipate through the
rest of the morning, with the area becoming almost entirely dry by
afternoon. Some updates were made to the forecast to bring it in
line with these current obs and the latest high resolution models,
with the main effect of ending precipitation a bit earlier than
previously thought. Otherwise, there were no significant changes.
The previous discussion below contains more information on the
rest of the forecast. -BPN

&&

.AVIATION...02/12Z TAFs...Wind speeds along the coast have turned
westerly with the front moving inland now. This will lead to rain
showers diminishing through the morning hours with relief
expected later today for ceilings. In fact, VFR could become
common across the region with skies generally clearing through the
afternoon and evening. North Bend may be the exception here with
MVFR sticking around. Timing of MVFR and rainfall will be tricky
this morning, but generally looking at the "roughest" conditions
this morning with noticeable improvements later today.


&&

.MARINE...Updated 230 AM Thursday, May 2, 2024...A weak front
will continue to move through the waters this morning with a modest
increase in short period west-northwest swell. A break later today
will bring calmer conditions this afternoon and evening; however,
the active pattern resumes Friday morning with rain over the waters
likely (90% - 100%) and small craft advisory conditions in place
through Saturday morning. Weak winds and a slight increase in short
period west-northwest swell dominated seas are expected during the
weekend with rainfall (no thunder) chances (60%-90%). The next in a
series of fronts is likely to arrive on Monday with conditions
hazardous to small craft possible Tuesday.

-Guerrero

&&

PREV DISCUSSION... /Issued 326 AM PDT Thu May 2 2024/

DISCUSSION...The pattern continues to be progressive into the
next week, with several fronts bringing wet and cool weather with
brief dry breaks in between. The first system moves through
overnight today with light showers lingering into the evening,
followed by a stronger front Friday into Saturday. Showery weather
continues into next week, with another weak front moving through
Monday.

A broad precipitation shield associated with a frontal system is
moving quickly ESE through southwest OR. Radar returns are
indicating some pretty good areas of precipitation, with areas of
40-50 dbZ embedded in the main band. This front will pass through
the region early this morning, followed by light, scattered
showers which will bring on-and-off again precipitation for the
remainder of the day, mostly over the higher terrain. With
seasonably mild temperatures, snow levels will remain at or above
5,000 feet and snow restricted to the higher mountains.

After a brief break in the weather, the next front arrives Friday
and slowly pushes inland into Saturday. Similar to the frontal
system today, this front will move in from the west, resulting in
much less downsloping for western valleys than in other patterns.
Precipitable water associated with this front, however, will be
greater with a stronger inflow of moisture, resulting in greater
precipitation amounts. Rain amounts of a half inch or more are
almost guaranteed for almost all areas in southern Oregon and far
northern California, with up to 2 or even 3 inches of rain
possible along the coast.

Snow levels will initially be quite high at the beginning of the
event, rising to above 7,000 feet, before decreasing overnight
Friday into Saturday to 3,000 to 4,000 feet as the cold front
passes and precipitation becomes more intermittent/showery. This
will result in snow lowering down to area passes, including those
over the Cascades on Hwys 140 and 138 (where we`re expecting 3-6
inches early Saturday through early Sunday) and Siskiyou Summit on
I-5 (likely less than an inch). As road surfaces are still quite
warm, a lot of this will melt on paved surfaces, but lower
visibilities could still make travel over the mountains difficult.

Showery, on-and-off again precipitation continues late Saturday
into Sunday as low pressure lingers aloft. Shower coverage will
shrink and taper off through the day Sunday as the low moves SE
and another transient ridge moves into the area. Another front
moves in Monday, this one much weaker with the majority of light
to moderate precip falling over northwest portions of the region.
Snow levels will generally be 4,000 to 5,000 feet. Onshore flow
and lingering moisture will lead to light, scattered showers
continuing into Tuesday. About a third of models included in the
National Blend indicate periods of precipitation are possible into
the mid-week, but the outlook for the late week/following week is
for warmer, drier conditions per the Climate Prediction Center.
-CSP


&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 8 AM Friday to 11
     AM PDT Saturday for PZZ350-356-370-376.

&&

$$