Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 251118

Area Forecast Discussion
National Weather Service Medford OR
418 AM PDT Thu Apr 25 2024

.DISCUSSION...The main update this morning was to issue a Winter
Weather Advisory for elevations above 5000 feet in the southern
Oregon Cascades from noon today through 2 PM Friday afternoon.
Snow levels will begin at 6000 to 6500 feet this afternoon into
this evening, then diminish to 5000 feet accompanying the highest
snowfall rates from around 2 AM Friday into Friday afternoon.
Amounts of 5 to 15 inches are forecast with highest amounts for
the back country. 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.

This is quite a shift in the weather given our most recent
conditions resembling early summer. Elsewhere, the cold frontal
passage and post-frontal showers is about to begin rain at the
coast, and will spread across the west side during this morning.
With a westerly flow and the downslope influence of the Cascades,
precipitation amounts and coverage accompanying the front will be
substantially less east of the Cascades during the afternoon.

As is often the case in our region, higher amounts will accompany
the passage of the axis of the trailing, cold, upper level low
early Friday into Friday afternoon.

Lingering showers and snow showers will gradually diminish through
all of Friday evening. A brief break between systems follows late
Friday night into Saturday morning.

The next, weaker front will bring (again) mainly west side
precipitation Saturday afternoon through Saturday evening.

Late Saturday night through all of Sunday into Monday morning, a
couple of additional, weak fronts will be focused north of our
area. But, they will bring scattered light showers to the coast
and Douglas County.

Monday afternoon through Tuesday, possibly into Tuesday evening,
is most likely to be a break in the action, allowing high
temperatures on Tuesday to rebound to slightly above normal...for
the first time since yesterday.

Another vigorous (for this time of the year) cold front is likely
to bring precipitation across the region, arriving at the coast
late Tuesday night then spreading inland Wednesday through
Wednesday night. The trailing upper trough is then anticipated to
bring showers and lower snow levels (around 4000 to 5000 feet)
Thursday/Day 7 into Friday night/Day 8.


.AVIATION...25/06Z TAFs...The currentMVFR conditions at the coast
are expected to remain through much of tonight, but with higher
level clouds moving in, the ceiling could lift just into the VFR
category. For the rest of the region, VFR conditions should remain
through the TAF period. With a front expected to move in Thursday
morning at the coast, the current cloud cover will at least remain
the same or increase through the night; making terrain obscuration
more common. The front is expected to arrive tomorrow afternoon.
This front will bring rain to the whole region, including east of
the Cascades, but it is unlikely to be heavy enough to restrict


.MARINE...Updated 215 AM Thursday, April 25, 2024...Seas remain calm
ahead of a weak front that will arrive this morning. Guidance
suggests enough fresh swell to bring steep seas to all waters will
precede the front, with elevated southerly winds arriving later this
morning and continuing into the evening. There will be 70-100%
chances of widespread showers over marine waters through Friday
evening, but thunderstorms are not expected. An existing Small Craft
Advisory in place from today at 5 AM through Saturday at 2 AM has
been expanded to cover all marine waters.

There are some small chances of more chaotic conditions during the
Small Craft hazard. The combination of fresh swell and gusty winds
as the front approaches may build occasional isolated areas of very
steep seas in waters north of Cape Blanco through Friday morning.
Additionally, wind gusts of 30 to 35 kts are forecast north of Cape
Blanco through this evening. Probabilistic guidance suggests a 10%
chances of wind gusts nearing gale strength over inner waters north
of Bandon this afternoon. There is not enough confidence in a steady
area or exact timing for these higher level of hazards, but the
possibility is worth acknowledging.

Seas are expected to calm during the day Saturday before active
weather returns on Sunday and looks to continue into next week as a
series of fronts and systems affect the area. Longer term guidance
suggests only occasional 10-40% chances of total seas exceeding 9
feet through next week, with the 40% chances associated with a low
pressure system settling near the Canadian coast on Tuesday. Future
further steep seas look likely at times during next week, but more
chaotic conditions are not expected. -TAD



PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM early this
     morning to 2 AM PDT Saturday for PZZ350-356-370-376.


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