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000
FXUS66 KMFR 252207
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
307 PM PDT Thu Apr 25 2024

.DISCUSSION...

.Short Term...Tonight through Saturday Night...Currently,
widespread showers cover much of southern Oregon and far northern
California, with snow levels currently around 6000 feet. Shower
activity will continue through this evening, then will reintensify
as the upper level trough axis swings overhead tonight and tomorrow.
As this occurs, snow levels will lower to 5000 feet, and snowfall
rates will peak between roughly 2 AM through midday Friday.
Amounts of 5 to 12 inches are forecast with highest amounts for
the back country and highest elevations. Recent warmth is sure to
limit amounts on roadways, but at the very least those traveling
around Crater Lake, Diamond Lake, and Willamette Pass should be
prepared for reduced visibilities. The highest peaks of the
Siskiyou Mountains, Warner Mountains, and Siskiyou County can also
expect to receive measureable accumulations.

Precipitation will taper off Friday evening into Friday night,
then after a short break Saturday morning as weak ridging passes
overhead, the next shortwave arrives Saturday. This will be a
quick moving and somewhat weak wave, but it will be the leading
edge of sustained zonal onshore flow that will persist through at
least Saturday night. This pattern is known to produce ongoing
light showers, and this is no exception, although most
precipitation will remain confined mainly along and west of the
Cascades. Snow levels are expected to remain fairly consistent,
throughout this time, hovering roughly around 5000 feet.

Temperatures throughout the short term will remain right around
normal for this time of year. -BPN

.LONG TERM...Sunday morning through Thursday night.

This cool unsettled flow will continue into Sunday with the best
chance of precipitation west of the Cascades and within Oregon.
However, locations east of the Cascades and in northern California
are anticipated to be dry.  This is most likely due to weak forcing
and a lack of moisture farther to the south under this zonal flow.
This synoptic pattern will likely continue into Monday as short
waves move through this zonal flow.

Heading into Tuesday,  500 mb heights appear more zonal over Oregon
as another short wave swings through the state of Washington.  This
appears to be the driest day as the chance of rain is generally
below 15% everywhere except along the coast near Cape Blanco and Coos
Bay. Given this drier trend, temperatures should push into the 70`s
in Medford, Grants pass and the upper 60`s in other locations across
our forecast area.

Eventually, an upper level low out of the Gulf of Alaska will likely
push into the Pacific Northwest around Wednesday. This should result
in another round of wetting rain, although the NBM probability of
precipitation of 0.01 inches over 12 hours only show a 50 to 60%
chance of rain. Therefore, some of the ensemble members might show
different times of arrival of the front on Wednesday night and
Thursday morning or it is drier than what some of the deterministic
data show.


The other thing that this low will bring is some cooler more
unstable air behind the cold front. This can be seen in the snow
levels falling down to 4000 feet behind the front, which should
eventually pass through sometime around Thursday.  Even with plenty
of solar heating, high temperatures are still anticipated to push
into the lower 60`s in many cities east and west of the Cascades.

Overall, the extended forecast looks active yet with little to no
impacts. We`re lacking significant moisture or forcing to bring
impactful rain or snow to the region. One may say it is very Spring
like for our forecast area.

-Smith



&&

.AVIATION (18Z TAFs)...

VFR will be the more dominate category through this cycle, but
low level moisture and rainfall could bring ceilings down to MVFR
for mainly North Bend. The inland terminals are more likely to
remain in VFR through this cycle. However, there will be no
shortage of cloud cover as we are expecting plenty of it through
this cycle, so mountain obstructions will be common across the
region. Additionally, light rainfall will also be common across
the area today, but pinpointing these exact moments at the
terminals will likely be difficult.

-Guerrero

&&

.MARINE...Updated 200 PM Thursday, April 25, 2024...A small craft
advisory remains in effect for all of the waters as a front
continues to make its way onshore today. The northern waters will
experience the strongest wind speeds with a couple isolated areas
perhaps seeing gales this afternoon. The front also brought
widespread rainfall to the area earlier today, but rainfall over the
waters has diminished quite a bit. In fact, satellite is indicating
some clearing in our western waters, and we are likely to see a lull
in activity over the waters until later tonight into Friday morning
when the next round of rainfall is anticipated.

While wind speeds diminish tomorrow, swell remains over the waters
and will keep seas hazardous to small craft. These conditions are
likely to last into Saturday morning. By Saturday afternoon, another
front will push into the area, and seas may become chaotic once
again. Additionally, we are going into a rainy pattern with chances
over the waters nearly every day in the forecast through middle next
week.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 2 PM PDT Friday above 5000 feet
     for ORZ027-028.

CA...None.

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

&&

$$