Laytonville, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

814
FXUS66 KEKA 241214
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
414 AM PST Tue Dec 24 2024

.SYNOPSIS...Series of atmospheric river storms will bring
a risk for flooding, strong winds and dangerous surf through
the weekend.

&&

.DISCUSSION...Cold front has been producing heavy rain through
the night with 12 hour totals ranging from 2 to 4 inches. Frontal
band will shift southeastward by mid morning with heavy rain rates
diminishing by noon. Instability trailing behind the boundary may
result in locally heavy downpours by late morning and early afternoon.
A break in the precip is expected by mid this evening, though a
few showers may continue to push onto the North Coast. Activity
is forecast to wind down by late evening with warming aloft. Warm
frontal precip ahead of the next shortwave will approach the
North Coast Wed AM. Precip will be quite light on Wed; sprinkles
or a few hundredths for mostly Del Norte and northern Humboldt.
Otherwise, main hazard will be patches of fog in the interior
valleys. Surface pressure gradients tighten through the day on
Wed. 925mb 60kt jet develops Wed night in advance of the next
frontal boundary and a wind advisory will be necessary for Del
Norte and Humboldt Counties. ECMWF ensemble indicates 50mph or
more for the Del Norte Coast, and 40 mph or so around the Humboldt
Bay area and Eel Delta. Higher elevations and ridges of Humboldt
will no doubt gusts to 50 mph or more. Even NBM has peak wind
gusts to 45-55 mph along the coast. Rates of surface pressure
falls may support a high wind warning for the Del Norte coast.
Instability increases Thu morning and robust convection or TSTMS
may develop near the coast and offshore over the waters.

Parade of atmospheric river storms will continue Thu night into
Sunday. Each storm will most likely generate strong winds and
heavy rain. Potential for flooding will increase over the
weekend. The exact magnitude of the flooding is not clear. Looking
at the ECMWF and WPC guidance, Sunday may be the day with the
greatest threat of flooding. ECMWF ensemble is wetter than the
GEFS with a wavy frontal boundary aimed at the northern portion of
the forecast area. We should finally see a break in the heavy
rain on Monday after passage of a large scale trough. DB

&&

.PREVIOUS AVIATION...The primary concern for the aviators this
afternoon and evening is the low level wind shear (LLWS), with
gusty SSE winds as secondary. Southerly winds have been increasing
as a frontal boundary approaches the region. Conditions are
expected to quickly worsen during the next hour or so with the low
level jet alongside the frontal boundary moving into the region.
Gusty southerly winds around 25 to 45 knots for KCEC and KACV, and
around 20 knots at KUKI late tonight. In addition, LLWS from 40
to 50 kt around 1000-2000 feet AGL in the coastal terminals
through 24/08Z, while marginal LLWS from 30-35kt will be likely
from 05Z-10Z from. Expect variable conditions across all TAF
terminals, with VFR to MVFR conditions dipping to IFR in periods
of heavy rain. Instability will increase behind the front, and
some isolated thunderstorm activity may develop over the coastal
waters and perhaps in the vicinity of ACV early Tuesday morning.
-ZVS

&&

.PREVIOUS MARINE...Winds have been increasing rapidly this
afternoon ahead of the frontal system. Southerlies will ramp up
this late this afternoon and evening, with widespread gale force
gusts. Gusts from 35 to 45 kt will be likely across the coastal
waters, with the strongest winds north of Cape Mendocino. A Gale
Warning is in effect through late this evening. Winds are
forecasted to diminish in the wake of the front late this evening.
However, the current large wave around 20 feet will continue to
slowly subside through Wednesday. Depending of how much this swell
subside this evening a Hazardous Seas Warning or Small Craft will
be followed the Gale Warning tonight.

In addition, there is the potential for thundertorms development
late tonight through Tuesday morning, especially south of Cape
Mendocino. Resulting in occasional gusty and erratic winds. The
storm cycle will remain very active through the remainder of the
week with additional frontal systems producing strong southerly
winds and large long period westerly swells. -ZVS


&&

.HYDROLOGY...The next rounds of rain look to be more persistent
with shorter breaks of no rain in between each IVT maximum. This
has the potential to cause more significant flooding in Del Norte,
Humboldt and Mendocino counties. Portions of northern Lake county
may see some heavy rain, but in generally rainfall amounts will
be less in Lake county. The CNRFC ensemble hydrographs indicate a
45 percent chance for the Eel River at Fernbridge to exceed minor
flood stage of 20 ft by Sunday evening. Stay tuned. DB

&&

.PREVIOUS BEACH HAZARDS...A High Surf Warning remain in effect
through 10 PM this evening for all coastal counties. As of 2 PM,
the buoys observation indicates the large W-NW long period swell
from 19 to 22 feet. Current breaker waves have been ranging from
26 to 30 feet along area beaches. Large waves will continue to
slowly subside this afternoon and evening, with breaker waves from
20 to 24 feet late tonight through Tuesday afternoon. As result,
the Warning will be downgraded to Advisory tonight. The large
breaking waves along the coast will lead to increased wave run-up
on beaches with waves topping and washing over large rocks and
jetties. These large waves can be erratic and unpredictable, and
will be capable of sweeping people into the frigid and turbulent
ocean water. In addition, mariners traversing the bar are urged to
exercise extreme caution or stay in port until the threat
subsides.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Flood Watch until noon PST today for CAZ101>106-109-110.

     High Surf Advisory until noon PST today for CAZ101-103-104-
     109.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 AM PST Wednesday for PZZ450-
     455-470-475.

&&

$$

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