952
FXUS66 KMFR 152352
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
452 PM PDT Sat Mar 15 2025

...Updated AVIATION discussion for 00Z TAFs...

.SYNOPSIS...

An impactful winter storm and atmospheric river will hit southern
Oregon and northern California on Sunday with feet of snow in the
central Cascades and inches of rain west of the Cascades. Model data
suggests this will be an unusually wet and snowy storm this time
of year for the region. This system will result in major travel
impacts in the high Cascades due to snow accumulation with minor
to moderate flooding impacts looking likely west of the Cascades
during Sunday and Monday.

&&

.DISCUSSION...

The leading edge of an atmospheric river is starting to hit
southern Oregon and northern California and bring the next wave of
precipitation to the area. Data continues to hint that this will
be a significant event for this time of year with feet of snow in
the Cascades and widespread 1 to 2 inches of rain west of the
Cascades.

With regards to snow, the bulk of it will fall in the high
central Cascades as is usually with most of our snow events.
Ensemble data suggests this could be an extreme event with the
50th to 75th percentiles showing 2 to 3 feet of snow with the 90th
percentile showing up to 4 feet of snow over 48 hours ending at
4pm Monday. This will be a significant snow event for our region,
especially if some of the stronger and snowier forecasts end up
coming to fruition. The 90th to 99th percentile 48 hour snow
forecast shows up to 5 feet of snow around Crater Lake, which
would be testing the 2 day record snowfall for that location.

Once the cold front moves through, we`ll see snow levels begin to
lower down to 2000 feet on average, although there is potential
that snow could make it to the valley floors on Sunday night into
Monday morning as another wave pushes relatively warm moist air
over the cold airmass in place over southern Oregon and northern
California. The probability of a significant snow even in the
valleys is <3%, although there were a few members that did show 1
to 3 inches of snow accumulating down to the valley floors. Again,
this seems the more unlikely solution and the most likely is
plenty of scattered snow shower with 1 to 2 inches of snow
accumulating around 2000 feet.

Aside from all the snow, we`re anticipating some river flooding
along our mainstem rivers and a few of the creeks. We have issued
a few river flood warnings as we have high confidence that these
rivers will at least exceed minor flood rating. The South Fork of
the Coquille at Myrtle Point is the one river that appears to be
coming up just short of minor flood at this time. Therefore, we
decided to keep the watch going for that forecast point. We`ll let
future shifts evaluate the flooding potential there.

Otherwise, all the rivers will see rapid rises given the amount
of rain coming down in such a short amount of time.

Finally, the wind also appears to be significant, especially east
of the Cascades on Sunday afternoon. 850 mb winds, which is close
to the surface over many locations is showing around 45kts to
maybe even up to 50 knots. Even with friction and surface
roughness, we should see widespread sustained winds in the 30 to
40 mph range for most of Sunday east of the Cascades. Wind gusts
up to 70 mph still seem reasonable over high and exposed
locations.

Once this cold front moves through, conditions will still remain
showery with winds on the downtrend by Monday evening into
Tuesday morning. High pressure will build in on Tuesday giving us
a brief break in this active weather pattern. It looks like we`ll
see another front pass around mid week and yet another one pass
through towards the end of the week bringing more rain and snow to
the region.

-Smith

&&

.AVIATION...16/00Z TAFs...Widespread showers continue across
northern California and southern Oregon this afternoon. Flight
levels are generally at VFR or MVFR across the area, with lower
ceilings over Brookings and Lakeview.

Rainfall is expected to increase tonight into Sunday morning. With
the amount and consistency expected, flight levels are expected to
be impacted by rainfall through most of the TAF period. Snow showers
will be nearly constant over the Cascades and western Siskiyou
County, possibly obscuring elevated terrain. Winds will be a factor
at and above the surface. Above the surface, low level wind shear is
expected through most or all of the TAF period for area terminals.
At the surface, At the surface, gusty winds will continue to affect
elevated terrain. Periods of gusty winds are possible for Roseburg
and Medford. Klamath Falls is expected to see increasing winds into
Sunday afternoon before speeds start to decrease. -TAD

&&

.MARINE...Updated 130 PM Saturday, March 15, 2025...Seas will
remain very steep and hazardous through this afternoon. A strong
front will approach the waters this afternoon bringing strong
south winds reaching gale force by late this afternoon/early
evening. Wind speeds will significantly diminish by Sunday
morning, and Gales will be confined to the southern waters mainly
south of Port Orford.

The front will move south of the waters later Sunday afternoon and
any south component to the winds Sunday afternoon will be weaker.
However, very steep and hazardous Seas are likely to persist through
Sunday afternoon, followed by Small Craft conditions Sunday night
through Monday. Winds and seas are expected to gradually diminish
Monday with calmer conditions possible Tuesday before south winds
increase again my mid week as another front approaches.

-Schaaf/Guerrero

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning until 11 PM PDT Sunday for ORZ027>031.

     Flood Watch through Sunday evening for ORZ021>026.

     High Wind Warning until 5 PM PDT Sunday for ORZ021-022-031.

     Wind Advisory until 8 AM PDT Sunday for ORZ023-024-026-029-030.

CA...Winter Storm Warning until 11 PM PDT Sunday for CAZ080-082-083.

     Flood Watch through Sunday evening for CAZ080.

     High Wind Warning until 5 PM PDT Sunday for CAZ081-084-085.

PACIFIC COASTAL WATERS...Hazardous Seas Warning until 5 PM PDT this
     afternoon for PZZ350-356-370-376.

     Gale Warning until 11 AM PDT Sunday for PZZ350-356-370-376.

&&

$$