030
FXUS66 KMFR 280957
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
257 AM PDT Sun Apr 28 2024

.DISCUSSION...Satellite imagery this morning shows some scattered
cloud cover west of the Cascades with some cirrus streaming over
the region. Radar shows some light showers along the coast, into
the Umpqua Basin, along the Cascades north of Lake of the Woods
and into the Douglas County Foothills. These showers are generally
light with only a few hundreths being reported at observation
sites. Onshore flow will maintain a 30-60% chance of showers north
and west of the Umpqua Divide today, with PoPs diminishing
quickly south and east of there. It looks like a mainly dry, at
least partly sunny day elsewhere (including here in the Rogue
Valley) with gusty breezes (25-35 mph) developing in the
afternoon.

An upper trough will swing through Monday morning and this will
bring a shot of showers (60-90% chance) to the coast eastward to the
Cascades. We can`t rule out a shower or two around the Rogue
Valley/Medford area Monday, but most of the time should be rain
free. Snow levels will drop to as low as 3000 feet by Monday
morning, but any snow accumulations will be confined to the
mountains generally above 4500 feet. Highest amounts will be from
about Crater Lake northward, where 2-5" could accumulate. Up to an
inch of snow is possible over Highway 140 near Lake of the Woods
with a skiff also possible on parts of Highway 97 north of
Chiloquin. So, if traveling early Monday morning, be aware of the
potential for some slick spots in those areas. South of the OR/CA
border, we don`t think much precipitation will make it over the
mountains and it will just be partly cloudy. As such, it`ll be cold
first thing Monday morning with some frost in the lower Klamath,
Scott and Shasta valleys.

This system exits to the east Monday evening, so shower chances
diminish, but it will be followed by another upper disturbance that
will swing through northern Oregon Tuesday and into Idaho Tuesday
night into Wednesday. Once again, we`ll be on the southern fringes
of this system, so PoPs (for showers) remain highest across the
north, lowest across the south. Snow levels bottom out near 2500
feet Tuesday morning, but again most, if not all, snow accumulation
will be in the mountains north of Crater Lake. Overall, temperatures
will remain near to below normal. Frost/freezing conditions west of
the Cascades are becoming more likely given the main area of precip
potential is north of the Umpqua Divide. Frost (lows 33-36F) chances
(50-80% chance) are highest for a few hours in the typically colder
locations (Illinois/Applegate Valley/Grants Pass areas) both Tue/Wed
mornings. Freezing conditions (<=32F) are possible (20-30% chance)
in the Illinois Valley as well, but much will depend on how much
cloud cover lingers during the overnight hours. Clearing looks more
widespread Tuesday night/Wednesday morning, providing a better
chance for frost/freeze for the Illinois/Applegate Valley and Grants
Pass areas.

As the upper trough shifts to the east, things dry out on Wednesday
with some sunshine and a slightly milder afternoon (high temps back
closer to seasonal normals). Models maintain some degree of
uncertainty after Wednesday with NBM still showing some PoPs (20-
30%) across NW portions of the CWA. This stems from a smaller
percentage of model members (GEFS/Canadian and to an even lesser
extent ECENS) showing a flat upper ridge and a weak trough, you
guessed it, skimming over the top Wednesday night into Thursday.
More plausible scenarios feature a bit stronger ridge and no precip
along with a more significant warm up. We`ll see how it shakes out,
but it does appear that temperatures should rebound to above normal
levels Thu/Fri. Models are showing a potentially more substantial
trough moving in next weekend, but confidence in the details is low
at this point. -Spilde/BR-y

&&

.AVIATION...28/06Z TAFs...A front will continue some light rain
showers from the coast to the Cascades overnight into early Sunday
morning. VFR will be the predominant condition, though areas of
ceilings/visibilities could lower to MVFR (perhaps even local IFR)
at times at the coast and into the Umpqua Valley. Higher terrain
will also be occasionally obscured.

For Medford and areas to the south and east, expect mostly VFR
through Sunday evening. Breezy westerly winds will be locally gusty
(20-25 kt) again during the afternoon into the evening. These winds
will be strongest east of the Cascades, including at Klamath Falls.

-DW

&&

.MARINE...Updated 220 AM Sunday, April 28, 2024...Weak high pressure
southwest of the waters will result in light to moderate west winds
and calmer seas. A weak front will move into the waters Monday with
increasing west winds, with low end small craft conditions possible.
The pattern will remain active Tuesday with an increasing northwest
swell between 8-10 feet moving into the waters, but all indications
suggest this will be short lived with seas diminishing Tuesday
night.

Calmer conditions are expected by mid week and could last into the
end of the week with light to moderate winds. -Petrucelli

&&

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

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$

MNF/MAP/MAS