Seiad Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

746
FXUS66 KMFR 270641
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1041 PM PST Thu Dec 26 2024

...Updated the aviation section...

.PREV DISCUSSION... /Issued 811 PM PST Thu Dec 26 2024/

DISCUSSION...Satellite imagery is showing the next fast-movnig
disturbance offshore heading toward the coast this evening. Low
pressure and a warm front are spreading widespread clouds and
precipitation into SW Oregon and northern California at this
time. The Coquille River at Coquille is currently rising and is
very near bankfull (20.0 feet) at this time. We have issued a
Flood Warning with the river expected to rise above flood stage
(21.0 feet) late tonight into Friday morning. The river could
subside below flood stage Friday night into Saturday, but with
the next surge of rainfall expected Saturday night into Sunday,
it is expected to go into moderate flood Sunday night into Monday
(>23.0 feet).

Rain rates have increased this evening as the low offshore
develops, and will continue to be moderate to heavy at times
overnight. Generally, we`re looking at rates of along the coast
and coast ranges of 0.10-0.30"/hour where the deep moist plume is
directed into the terrain through about 4 am. Some of the locally
favored areas could see rain rates a bit higher than that, but
probably less than 0.50"/hour. Expect additional rises on area
creeks, streams and rivers along with ponding of water on
roadways.

Models are showing a decent mid-level (850 mb) jet coming in
after 06Z, probably between 07-09Z with OTH-ACV pressure gradient
nearing -9 mb. This could bring a surge of wind to the coast,
especially south of Bandon and also the headlands from Cape Blanco
southward. We`ve upgraded to a High Wind Warning there for the
potential of 70 mph wind gusts. While still quite hazardous, we
are NOT expecting a repeat of last night. The strongest winds
should only last 1-2 hours at most and will subside quickly once
the low moves onshore, by 2 am PST. Wind advisories are out for
most of the remainder of the area, but especially the Shasta
Valley, southern Rogue Valley and Klamath Basin where gusts could
be 45-55 mph. Mid-level winds are very strong over the east side
overnight into Friday, so higher terrain over there from Winter
Rim (Summer Lake) could have warning levels gusts. As such, we
upgraded to a High Wind Warning in those areas as well.

After a break during the day Friday, the next impulse will arrive
at the coast Friday evening. While it will be windy there again,
gradients peak around -6 mb OTH-ACV, so peak gusts of 45-55 mph
remain below warning levels. This impulse will move across SW
Oregon and NorCal, but stall, keeping periods of at least moderate
precip over a large part of the area. Snow levels during this time
surge (at least briefly to 7000-8000 feet, so there will be a mix
of rain and snow for the higher elevations, including at Crater
Lake Rim/Mt A. As such, winter impacts appear minimal.

The main story continues to be Saturday night into Sunday as the
next deep moist plume with solid IVT arrives from the SW. This
will bring a renewed risk of heavy rainfall. With already
saturated soils, runoff will be high and the risk for flooding
goes up. Be on the lookout for additional potential flood products
as we get closer to this event. -Spilde

&&

.AVIATION...27/06Z TAFS...The next strong front has reached the
coast and will bring another round of strong winds, low level wind
shear, mountain obscuration, and light to moderate precipitation
with mainly IFR to MVFR. The front will spread inland overnight into
Friday morning, then conditions briefly improve during the late
morning into the afternoon. Gusty winds and precipitation look to
ending by early afternoon on the east side.

After the precipitation becomes less widespread late Friday morning,
mainly MVFR is likely to linger with a few light coastal and
mountain showers, and areas of mountain obscuration. The next
strong, warm system will reach the coast around 00Z early Friday
evening, spreading slowly inland Friday night through Saturday. It
will bring another round of low level wind shear to each of the
terminals by Friday evening with mountain obscuration, mainly light
to moderate rain, and mainly MVFR conditions.
-DW

&&

.MARINE...Updated 800 PM PST Thursday December 26, 2024...A series of
strong fronts will bring south gales tonight, Friday evening, and
Saturday night into early Sunday morning. There will be lulls in
wind speeds between fronts, but seas will remain very high and steep
to very steep from now into Sunday morning. Improving conditions
follow early next week. -DW

&&

.BEACH HAZARDS...Updated 200 PM PST Thursday December 26, 2024...
Swell dominated seas will continue to produce dangerous surf through
the weekend. Surf conditions will be occasionally worsened by high
winds and seas as fronts pass each day through Sunday. Breaking
waves in excess of 30 feet remain possible through the weekend.

During these events, extremely large breaking waves will create very
hazardous conditions along beaches and area shorelines. Waves will
inundate beaches and surge into normally dry areas, especially at
times of high tide. Infrastructure damage and significant beach
erosion can be expected. Stay away from area beaches during this
period of active weather. -Wright

&&


PREV DISCUSSION... /Issued 235 PM PST Thu Dec 26 2024/

SHORT TERM...Overview:

Our active weather continues today with hazards from the coast
through the Cascades over into the eastside. Our current Winter
Weather Advisory will expire late tomorrow morning. A new Wind
Advisory is in place across the forecast area as wind speeds are
expecting to ramp up again tonight through Friday morning. We are
also looking at higher elevation snowfall and heavy rainfall
potential along/near the coast. Snow levels start to quickly rise
Friday afternoon into Saturday and the flood potential may start to
ramp up with snow melt and moderate to heavy rainfall on top of
already saturated soils.

Further Details:

Lingering precipitation will continue through the short term.
Frontogenesis is progged to weaken through the day with snow levels
rising, but we are still expecting snowfall to occur at elevations
mainly above 5000 feet, but it would not be out of the question to
see very light amounts elsewhere on the eastside at even lower
elevations. Another period of increased frontogenesis will occur
tonight around 10pm and continue through late morning on Friday, so
we could see another peak in snowfall rates between 10pm and 2am for
those locations within the advisory. Thereafter we will likely see
snowfall rates quickly diminishing. In fact, we may be able to
cancel the advisory early by a few hours or so depending on how the
500mb wave progresses through the region. Rainfall will then become
our main issue which could lead to flooding, especially areas near
the coast on/near the Coquille. We are currently highlighting this
threat in the Hydrologic Outlook, in addition to river forecast from
the River Forecast Center. The peak in the flooding will be in the
long term forecast, but we are currently looking at impacts starting
around the 29th and continuing through the 30th. Please see long
term discussion for more details.

LONG TERM...The long term will begin with light to moderate rain
mainly in northern California and in southern Oregon west of the
Cascades at the coast. A cold front will be moving in and by the
late afternoon Saturday, there will be heavy rain in the forecast.

The heaviest rain will fall late Saturday afternoon and continue
through Sunday morning. There is a 50-60% probability for eastern
Curry County and far western Josephine County to see 1 inch of
rainfall in 6 hours Saturday night. Climatologically, PWATs are
around 0.45" near the end of the year at Medford. Forecast PWATs
with this system are forecast to be double that. 6 hour rainfall
forecast for the Rogue Valley could reach 0.25"-0.50" Saturday
night. More westerly upper level flow will help support the moisture
intake for the area with RHs forecast to stay above 80% until Sunday
night.

The probability for 4 inches of snow to fall in 6 hours in the
Cascades, including the Crater Lake area, is near 60-70% Sunday
morning. Between Sunday morning and Monday morning, 8 to 15 inches
could fall.

The heavy rain along with snow melt will bring a concern for
flooding for small streams and rivers. As of this afternoon the
forecast calls for the Coquille River at Coquille to reach action
stage tonight and will reach minor flood stage by Sunday morning
before peaking in to Moderate Flood Stage Sunday night into Monday.
The Rogue River at Agness is forecast to reach Minor Flood Stage
Sunday morning and crest at ~21 feet Sunday afternoon. Please see
ESFMFR for more information on the Flood Potential Outlook.

The introduction of ridging to the PNW Monday will bring calmer
conditions through the day Monday into Tuesday. This will also means
the chance for lighter winds. The threat of fog will need to be
evaluated those mornings as forecast soundings are favoring
inversions to set up at least in the Umpqua Basin. Temperatures will
return to near normal for this time of year by early next week.
After the quieter start to the week the next system will come just
in time for the New Year, but they will be lighter and focus on
areas west of the Cascades. -Hermansen

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 AM PST Friday for ORZ027-028-
     030.

     Wind Advisory until 4 AM PST Friday for ORZ023-024-026-029.

     High Wind Warning until 10 AM PST Friday for ORZ021-022-030-031.

     High Surf Warning until 7 AM PST Sunday for ORZ021-022.

CA...Winter Weather Advisory until 10 AM PST Friday for CAZ080-082-
     083.

     Wind Advisory until 4 AM PST Friday for CAZ081-084.

     High Wind Warning until 10 AM PST Friday for CAZ085.

PACIFIC COASTAL WATERS...Gale Warning until 7 AM PST Sunday for
     PZZ350-356-370-376.

&&

$$