Witter Springs, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

899
FXUS66 KEKA 261357
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
454 AM PST Thu Dec 26 2024

.SYNOPSIS...Series of atmospheric river storms will continue
to bring periods of heavy rain, possible flooding, strong winds
and dangerous surf through the weekend.

&&

.DISCUSSION...Strong winds have been diminishing early this
morning. Peak wind gusts to 66 mph occurred at Crescent City
Airport. 58 mph was recorded at the Crescent City Harbor Tidal
gage. Surface trough was still just offshore and gusty winds will
continue through early morning before diminishing by mid morning.
Winds will increase again late in the day and early evening as
another potent front/low pressure system approaches the PacNW coast.
Winds do not appear quite as strong per NBM 90th percentile peak
gusts. HREF probability for gusts more 58 mph is 50% and 30% for
more than 60 mph. Winds to 50 mph are sufficient to cause damage
or bring trees down. A wind advisory has been hoisted for coastal
Del Norte and interior mountains of Humboldt and Del Norte tonight.
Winds should diminish below advisory threshold on Friday, but it
will remain breezy. Frontal boundary will approach over the weekend.
There are indications of surface wave development and potential for
strong winds. Right now it looks like a solid wind advisory event,
but if a frontal wave develops or a surface low spins up, a high
wind warning and damaging winds may be the final outcome. ECMWF
ensemble and NBM guidance has been honing in on Saturday night or
early Sunday morning. Breezy westerly winds are expected on the
backside of the front on Sunday and damaging wind gusts are
possible. This will need to be watched closely.

Longer duration moderate to heavy rain and potential for flooding
increases Friday into Sunday as at least 3 more IVT plumes
intersect the coastal terrain. See hydrology section below. A
break in the active and wet weather is expected on Monday after
large scale trough passage. Surface high pressure will build and
promote drying offshore flow on Monday. After multiple days of
rain, fog and low clouds will form in the interior valleys. Low
probabilities for light rain return on Tue and increase Wed-Thu
next week. Exact magnitude and timing of rain remains uncertain,
though AR landfall diagram indicates a 50% chance for IVT`s over
250 kg/m/s with a frontal system mid week. Stay tuned. DB

&&

.AVIATION...Biggest problem is low-level wind shear potential. Low-
level jet will be strong enough, despite gusty surface winds, to
warrant the mention of LLWS in the forecast. Overall chances of
lowest ceilings and visibility arrive rather late in the forecast,
peaking at 65-85% chance of ceilings below 3K feet between 02Z and
09Z Friday, with MVFR visibility reaching 55-75% chance shortly
before the timing of the greatest probability ceilings less than 3K
feet. Both KCEC and KUKI stand a better than 50% chance of ceilings
in the 1-2K range. Strongest winds along the coast actually arrive
in the 05Z-08Z time frame, with mean peak gusts for KCEC near 34KTS
and 24KTS for KACV. /MH

&&

.MARINE...High confidence that we will need to convert the Hazardous
Seas Watch to a Hazardous Seas Warning from 11Z Thursday (this
morning) through at least 04Z Friday with the large swell that has
built in and as south winds begin to subside a bit. Winds will
hardly be considered light, however with still a 100% chance of
gusts above 22KT tonight. NBM solutions point toward potentially
continuing the Hazardous Seas Warning through Thursday night for the
northern outer waters as seas subside a bit temporarily (although
small craft conditions will almost certainly be met at this time due
to primarily winds). Hazardous Seas may return to all waters for
Friday if trends continue. Expect another large northwest swell to
build in by Friday night into Saturday. /MH

&&

.HYDROLOGY...Rivers, streams and creeks will rise sharply again
by early Friday morning as another front/IVT plume generates a
bout of moderate to heavy rain tonight. IVT plumes have been
progressive with sufficient time in between each period of heavy
rain for water levels to drain. Soils remain saturated and run off
responses have been quick. The next IVT plume will follow Thu
evening and overnight and rivers will once again rise rapidly.
Longer duration moisture flux with sustained (24-48 hours) of
moderate-to-heavy rain for the northern basins raises concerns for
more significant areal flooding and main stem river flooding this
weekend. Ensemble hydrograph plumes indicate low probabilities,
generally less than 20%, for flood stage exceedance. The Eel
River at Fernbridge has about a 45% chance of exceeding minor
flood stage of 20 ft this weekend and the Russian River at Hopland
about a 39% chance of exceeding minor flood stage of 15 feet. DB

&&

.BEACH HAZARDS...An incoming large, long-period westerly swell
is expected Thursday morning with similar wave dimensions and
resulting beach oriented surf around 20 to 23 feet, lasting well
into Sunday with a brief lull late Thursday night. A high surf
advisory has been issued for this initial s well before a lull in
breaking waves and subsequent return of large breaking waves shore-
side. Beachgoers, please be aware. These large waves can be erratic
and unpredictable, and will be capable of sweeping people into the
frigid and turbulent ocean water. Stay safe by remaining off
jetties, rocks, wet sand )where waves have previously broken) and
steep beaches. If you end up going to the beach, be on high alert
and never turn your back to the ocean.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     High Surf Advisory until 11 PM PST this evening for CAZ101-
     103-104-109.

     Wind Advisory from 6 PM this evening to 3 AM PST Friday for
     CAZ101-102-104>106.

     Winter Weather Advisory until 8 AM PST this morning for
     CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Hazardous Seas Warning until 8 PM PST this evening for
     PZZ450-455-470-475.

&&

$$

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