Severe Thunderstorm Warning 1, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
258 PM PDT Tue Aug 15 2023

.SYNOPSIS...Isolated, mostly dry thunderstorms continue to be
possible across portions of the interior this afternoon.
Additional thunderstorms are possible later in the week, but some
rain is expected with these. Above normal temperatures will
continue through Wednesday with temperatures slowly cooling later
in the week and into the weekend.

&&

.DISCUSSION...The upper level low off the coast of CA is
continuing to bring thunderstorms to the area this afternoon. For
now it looks like they will remain over the interior. These are
expected to only be isolated, however since they are high-based
they will likely be mostly dry. So have a red flag warning in
place for Trinity county. Thunderstorms elsewhere look to be more
isolated. The NAMNEST shows some ongoing showers continuing
overnight in the modeled reflectivity, but that is the outlier so
have left them out of the forecast for now. Hot temperatures
persist across the area with the with highs over 100 degrees in
much of the interior and the coast seeing highs in the upper 60s
to low 70s. Tonight will be another warm tonight with most areas
staying in the 60s and 70s.

Wednesday has the potential to see additional thunderstorms
across the interior, however confidence is low on this. Even the
NAM has less than 100 j/kg of CAPE on the Weaverville sounding in
the afternoon. The modeled reflectivity shows some showers or
possible thunderstorms north of Mendocino county so have
thunderstorms in the forecast still. Hot temperatures are expected
to persist again on Wednesday, although cloud cover could limit
this slightly. However with the warm overnight lows will continue
to elevated the heat risk so have left the excessive heat warning
and advisory in place.

Thursday and through the weekend the upper level low remains off
the central CA coast. This will continue to bring the potential
for showers and thunderstorms. Overall it looks like temperatures
will cool off and the storms are expected to become wetter. Early
next week some of the models are showing an upper level trough
dropping down out of the northwest. There are still a lot
differences in the ensembles and therefor uncertainty in the
pattern.

&&

.AVIATION...Weather conditions were interesting at CEC as a line
of mostly elevated Thunderstorms moved over Southern Oregon and
Del Norte County this morning with VCTS being frequently
reported...starting around 5AM. An actual thunderstorm was
reported and impacted CEC from 6-7 am with as much/little as 0.10
falling. CEC also reported unusually coastal stratus with the
convection; brief Cigs lowered into IFR. A little bit of elevated
smoke also moved from the north. Elsewhere...Thunderstorms/showers
moved into or built over interior mountains which could cause
concern for local general aviation. Aviation along the Mendocino
coast was impacted by a stratus surge moving northward; stratus-
fractus was seen along the southern Humboldt coast in the
afternoon. Various model data indicating some coastal marine Cigs
over the North Coast overnight which has been somewhat
acknowledged in the TAFS. /TA

&&

.MARINE...Relatively light winds are forecast today. Northerly
winds are expected to increase on Wednesday afternoon. NW swell
will gradually subside through tonight. Northerly winds are
forecast to increase over the N outer waters by Wednesday
afternoon, with these winds expanding across much of the outer
waters by Thursday night and Friday. Eventually, another Small
Craft Advisory will be needed for the outer waters, but that's
still 36 to 48 hours out. /SEC

&&

.FIRE WEATHER...Isolated thunderstorms are expected across the
interior areas again this afternoon. These are expected to be
fairly dry again. Strike numbers are uncertain, but it looked like
there will be enough to warrant a red flag warning. In addition
there will be some slightly stronger than afternoon winds. These
are expected to be 10 to 15 mph out of the northwest with gusts to
25 mph over favored areas and higher terrain. These are expected
to come to an end with once the temperatures start to cool this
evening. Wednesday there is the potential for thunderstorms along
with hot and dry conditions. MKK

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Heat Advisory until 11 PM PDT Wednesday for CAZ102-104.

     Excessive Heat Warning until 11 PM PDT Wednesday for
     CAZ105>108-110-111-113>115.

     Red Flag Warning until 10 PM PDT this evening for CAZ283.

NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

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Special Weather Statement
National Weather Service Eureka CA
254 PM PDT Tue Aug 15 2023

CAZ105-106-108-152230-
Southern Trinity CA-Southern Humboldt Interior CA-
Northern Humboldt Interior CA-
254 PM PDT Tue Aug 15 2023

...A CLUSTER OF STRONG THUNDERSTORMS WILL IMPACT EAST CENTRAL
HUMBOLDT AND WEST CENTRAL TRINITY COUNTIES THROUGH 315 PM PDT...

At 253 PM PDT, Doppler radar was tracking a cluster of strong
thunderstorm west of Forest Glen, or 19 miles southwest of Hayfork,
moving northwest at 10 mph. The storms will impact the Mad River and
Dinsmore along Highway 36.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Dinsmore.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4035 12332 4029 12340 4052 12376 4066 12353
TIME...MOT...LOC 2153Z 126DEG 10KT 4041 12344

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

JJW

Special Weather Statement
National Weather Service Eureka CA
305 PM PDT Tue Aug 15 2023

CAZ108-152230-
Southern Trinity CA-
305 PM PDT Tue Aug 15 2023

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN TRINITY COUNTY
THROUGH 330 PM PDT...

At 303 PM PDT, Doppler radar was tracking a strong thunderstorm 11
miles southeast of Ruth, or 18 miles southwest of Yolla Bolly
District Rs, moving northwest at 10 mph towards Ruth

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of southwestern
Trinity County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4017 12312 4011 12319 4024 12342 4035 12329
TIME...MOT...LOC 2203Z 129DEG 9KT 4018 12322

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

JJW

Special Weather Statement
National Weather Service Eureka CA
419 PM PDT Tue Aug 15 2023

CAZ106-108-152345-
Southern Trinity CA-Southern Humboldt Interior CA-
419 PM PDT Tue Aug 15 2023

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN HUMBOLDT AND
SOUTHWESTERN TRINITY COUNTIES THROUGH 445 PM PDT...

At 417 PM PDT, Doppler radar was tracking a strong thunderstorm 7
miles southwest of Ruth, or 18 miles east of Garberville, moving
northwest at 5 mph towards the Zenia area.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Zenia.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4017 12344 4015 12347 4022 12364 4029 12347
TIME...MOT...LOC 2317Z 136DEG 5KT 4019 12346

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

JJW

Special Weather Statement
National Weather Service Eureka CA
434 PM PDT Tue Aug 15 2023

CAZ106-108-160000-
Southern Trinity CA-Southern Humboldt Interior CA-
434 PM PDT Tue Aug 15 2023

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN HUMBOLDT AND
SOUTHWESTERN TRINITY COUNTIES THROUGH 500 PM PDT...

At 432 PM PDT, Doppler radar was tracking a strong thunderstorm over
Alderpoint, or 13 miles northeast of Garberville, moving west at 10
mph

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Alderpoint and Fort Seward.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4014 12345 4009 12355 4017 12371 4023 12364
TIME...MOT...LOC 2332Z 091DEG 10KT 4018 12356

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

JJW

Special Weather Statement
National Weather Service Eureka CA
453 PM PDT Tue Aug 15 2023

CAZ110-111-160015-
Northwestern Mendocino Interior CA-
Northeastern Mendocino Interior CA-
453 PM PDT Tue Aug 15 2023

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN MENDOCINO COUNTY
THROUGH 515 PM PDT...

At 451 PM PDT, Doppler radar was tracking a strong thunderstorm 10
miles east of Laytonville, moving northwest at 20 mph towards Dos
Rios across Highway 162.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Dos Rios.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3962 12322 3958 12328 3971 12340 3976 12330
TIME...MOT...LOC 2351Z 139DEG 17KT 3964 12330

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

JJW

Special Weather Statement
National Weather Service Eureka CA
458 PM PDT Tue Aug 15 2023

CAZ105-107-160030-
Northern Humboldt Interior CA-Northern Trinity CA-
458 PM PDT Tue Aug 15 2023

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN HUMBOLDT AND
NORTHWESTERN TRINITY COUNTIES THROUGH 530 PM PDT...

At 457 PM PDT, Doppler radar was tracking a strong thunderstorm 8
miles north of Denny, or 15 miles east of Hoopa, moving northwest at
5 mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of northeastern
Humboldt and northwestern Trinity Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4122 12344 4115 12338 4116 12336 4116 12335
      4114 12332 4114 12330 4112 12328 4112 12327
      4109 12325 4101 12338 4112 12355
TIME...MOT...LOC 2357Z 130DEG 5KT 4107 12337

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

JJW