765
FXUS66 KEKA 161245 CCA
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
448 AM PDT Sun Mar 16 2025

.SYNOPSIS...Heavy rain just north of the Oregon border will shift
southeastward across the area today, eventually reaching southern
Mendocino and southern Lake Counties by this evening. Showers and
locally brief heavy rain will follow tonight. Strong and potentially
damaging southerly winds will spread southeastward with the front.

&&

.DISCUSSION...Wavy frontal boundary north of CA/OR border
will shift southeastward across the area today. High probabilities,
over 80%, for heavy rainfall rates (>0.30in/hr) will spread into
Del Norte this morning. A few CAMS such as the HRRR and ARW
support higher rates, 0.50in/hr to 0.75in/hr as the subtropical
moisture stream (IVT > 500kg/ms) intersects the coastal terrain.
MRMS radar precip rates and automated rain gages so far indicated
light to moderate rates (< 0.15in/hr). Heavy rain will also spread
into Humboldt (most tied to the terrain) and eventually into Mendo
and Lake by mid afternoon and early evening. 1 inch or more in 6
hours is expected (60-70% chance) for the mountains of Del Norte and
Humboldt (King Range espeically) and far NW Mendo. A flood watch
remains in effect for Del Norte and Humboldt today with heavier rain
rates on the way with the incoming atmospheric river storm (AR2).

Winds overnight have been cranking along the Del Norte coast with
Crescent City ASOS reporting sustained winds of 41 mph with peak
gusts around 67 mph. Elsewhere, winds have been howling in the usual
wind prone sites with gusts to 60-70 mph. A frontal wave has been
forming offshore and delaying the arrival of the front and strong
winds along the Humboldt County coast. Frontal boundary approaches
Humodlt Bay by late morning and winds are forecast to increase. A
few CAMS inidicate a high reflectivity line too with winds peaking
around 45-50 mph right around noon, give or take an hour or two.
Likewise on the Mendocino coast, winds peak right before frontal
passage near noon. Winds will decrease after frontal passage, but
should pick up again in response to a decaying or filling surface
low that is forecast to meander about just offshore Pt St George.
Wind speeds and gusts per all the CAMS and NBM are forecast to
remain below criteria for extension of wind warnings and advisories.
It will still be breezy/windy especially around the headlands and
over the ridges.

Wind and rain will decrease substantially behind the front bringing
an end to the most impactful weather from this atmospheric river
Sunday evening. However, additional shower activity and possibly
isolated thunder is expected in the wake of the front as the parent
low moves overhead in a colder environment. With snow levels
falling back to around 3000 feet, some higher passes may have snow
accumulations and the potential for chain requirements through
Monday night. HREF probs for 1"/hr are no more than 20% for hwys
36 and 299. 6-hourly running means are < 1 inch and suspect there
will be some snow, but not sufficient at this time to warrant an
advisory.

High pressure will build on Tuesday providing generally dry
weather for much of the area. Some light showers may linger for
the North Coast and across Del Norte with about a 20-30% chance
for 0.01in. By evening probabilities diminish to less 10% for
0.01in, before southerlies start to ramp up in advance of the next
frontal boundary and a narrow plume of IVT > 250kg/ms arrives on
Wed. Frost and subfreezing minimum temperatures are a concern for
Tue morning, however abundant fog and low clouds in the interior
valleys of Mendo and Lake may counteract the long wave cooling.
NBM probabilities are 90 to 100% for 32F or less. This will need
to be looked at more closely in the next day or so once we get by
the ongoing atmospheric river storm.

Additional frontal systems are forecast for the latter portion
of the week and over the weekend. GEFS and ECMWF ensemble member IVT
forecast indicate means just under 250kg/ms. GEFS has higher
probabilities along 40N and suggest potentially a wetter outcome
than the ECMWF. Perhaps the ECMWF will trend southward and wetter
for NW Cal. Impacts appear to be low from this late week front. DB

&&

.AVIATION...Strong southerly winds and moderate rainfall will continue
across all terminals this morning, especially along the north coast.
Gusts exceeding 60 mph are possible at CEC, 30 to 50 mph at ACV.
Gusts 20 to 30 mph will reach UKI around 15 to 18Z. Wind shear is
still realized as highest gusts from the coastal jet have not yet
mixed down - this may change as conditions become more unstable and
strong gusts reach the surface. Periods of moderate to heavy
rainfall will encourage IFR to briefly LIFR ceilings and viz, more
consistently at CEC where the heaviest precip is expected.
Otherwise, MFR conditions will likely prevail. This will be a long-
lived threat with sustained 20 to 30 knot winds and >45 knot gusts
and rain continuing through this afternoon when the stalled front
finally moves onshore. Areas of strongest winds and heavy rain will
shift slightly south between 18 to 21Z, briefly worsening conditions
along the Mendocino coast and finally bringing the heaviest rainfall
to to UKI.

&&

.MARINE...Strong Gale Force winds will continue through this afternoon
as a cold front stalls offshore near the Oregon/California border.
Isolated Storm Force gusts exceeding 50 knots are possible,
especially in the inner waters near Point St. George. Gale
conditions are likely to expand into the southern waters south of
Cape Mendocino by early this afternoon as this front finally moves
onshore. Winds will rapidly decrease behind the front, leaving the
sea state dominated by a long period westerly swell as it peaks this
afternoon. Steep wind waves may require a period of Hazardous Seas
warnings this evening before diminishing with lighter SW winds. Wave
heights are forecast to gradually fall below 10 feet during the
first half of the week amidst light northerly winds. Models are
beginning to hone in on another front arriving Wednesday. Confidence
is increasing for another round of near-Gale force winds focused in
the northern waters.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Flood Watch through this evening for CAZ101>106.

     High Wind Warning until 2 PM PDT this afternoon for CAZ101-
     102.

     Wind Advisory until 5 PM PDT this afternoon for CAZ103>106-
     108>112.

     Winter Storm Warning until 11 PM PDT this evening for
     CAZ107.

     Wind Advisory from 8 AM this morning to 8 PM PDT this
     evening for CAZ113>115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Gale Warning until 3 PM PDT this afternoon for PZZ450-470.

     Small Craft Advisory until 3 AM PDT early this morning for
     PZZ455-475.

     Gale Warning until 3 PM PDT this afternoon for PZZ455-475.

&&

$$

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