Frost Advisory 18, NWS Eureka, CA

885 
WWUS76 KEKA 140327
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
827 PM PDT Tue May 13 2025

CAZ107-108-110-111-114-141130-
/O.CON.KEKA.FR.Y.0018.250514T1000Z-250514T1600Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Northern Lake-
Including Trinity Center, Ruth, Hayfork, Gravelly Valley Airport,
Covelo, and Potter Valley
827 PM PDT Tue May 13 2025

...FROST ADVISORY REMAINS IN EFFECT FROM 3 AM TO 9 AM PDT 
WEDNESDAY...

* WHAT...Temperatures as low as 35 will result in frost formation.

* WHERE...Trinity County, Northern Mendocino Interior, and Northern 
  Lake.

* WHEN...From 3 AM to 9 AM PDT Wednesday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

* ADDITIONAL DETAILS...The coldest locations will be in the valleys, 
  especially higher elevation valleys.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

EYS

992 
WWUS76 KEKA 140340
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
840 PM PDT Tue May 13 2025

CAZ107-108-110-111-114-141600-
/O.CON.KEKA.FR.Y.0018.250514T1000Z-250514T1600Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Northern Lake-
Including Trinity Center, Gravelly Valley Airport, Ruth, Covelo,
Hayfork, and Potter Valley
840 PM PDT Tue May 13 2025

...FROST ADVISORY REMAINS IN EFFECT FROM 3 AM TO 9 AM PDT 
WEDNESDAY...

* WHAT...Temperatures as low as 35 will result in frost formation.

* WHERE...Trinity County, Northern Mendocino Interior, and Northern 
  Lake.

* WHEN...From 3 AM to 9 AM PDT Wednesday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

* ADDITIONAL DETAILS...The coldest locations will be in the valleys, 
  especially higher elevation valleys.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

EYS

530 
WWUS76 KEKA 140343
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
843 PM PDT Tue May 13 2025

CAZ107-108-110-111-114-141600-
/O.CON.KEKA.FR.Y.0018.250514T1000Z-250514T1600Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Northern Lake-
Including Potter Valley, Gravelly Valley Airport, Trinity Center,
Covelo, Hayfork, and Ruth
843 PM PDT Tue May 13 2025

...FROST ADVISORY REMAINS IN EFFECT FROM 3 AM TO 9 AM PDT 
WEDNESDAY...

* WHAT...Temperatures as low as 35 will result in frost formation.

* WHERE...Trinity County, Northern Mendocino Interior, and Northern 
  Lake.

* WHEN...From 3 AM to 9 AM PDT Wednesday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

* ADDITIONAL DETAILS...The coldest locations will be in the valleys, 
  especially higher elevation valleys.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

JB

753 
WWUS76 KEKA 141625
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
925 AM PDT Wed May 14 2025

CAZ107-108-110-111-114-141730-
/O.EXP.KEKA.FR.Y.0018.000000T0000Z-250514T1600Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Northern Lake-
Including Del Loma, Zenia, Junction City, Hayfork, Ruth, Hyampom,
Laytonville, Big Bar, Peanut, Helena, Covelo, Willits, Legget,
Gravelly Valley Airport, Weaverville, Potter Valley, Trinity
Center, Carrville, Douglas City, and Forest Glen
925 AM PDT Wed May 14 2025

...FROST ADVISORY HAS EXPIRED...

The threat has ended.

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

DB

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
426 AM PDT Tue May 13 2025

.SYNOPSIS...Drying and warming trend today through the remainder
of the week. Breezy northwest winds is anticipated each afternoon.
A slight chance of precipitation returns on Saturday, but mostly
dry weather conditions most likely persist over the weekend.

&&

.DISCUSSION...Latest GOES-West satellite imagery and surface
observations depicted low level moisture across much of the
forecast area overnight, with some sprinkles been reported. Low
temperatures have been in the upper 30's to mid 40's across the
interior valleys.

A H5 shortwave ridge will begins to build into the area today,
bringing a slightly drier airmass. Breezy northwest winds of 20-
30 mph are possible along the coast this afternoon as well.
Afternoon inland temperatures will warm up into the mid 60's to
mid 70's. Enhancing onshore flow will remain the coastal areas in
the mid to upper 50's. Areas of valley fog are expected to develop
Tuesday night into Wednesday. Overnight temperatures are forecast
to be remain in the upper 30's to mid 40's.

A drying and warming trend will continue through the remainder of
the work week across Northwest California. Interior high
temperatures are anticiapated to warm up into the mid 70's to low
80's, with the warmest day Thursday and Friday. Breezy conditions
are expected each afternoon as a thermal trough develop inland.

Ensemble clusters and determonistic model shows a upper level
trough digging southward from the Gulf of Alaska Friday night
into the weekend. About 25% of the ensemble members indicate a
slightly wetter outcome on Saturday, with showers mostly over the
interior and perhaps a push of marine moisture and low clouds.
Otherwise, dry weather with near or below normal high temperatures
in the interior is the most likely outcome for this weekend. /ZVS

&&

.AVIATION...After the passage of a front and light rainfall, patchy
stratus has developed and lingered through portions of the coast and
into some of the interior valleys. Ceilings are maintaining MVFR
levels with dips into IFR. Going into sunset, lower levels are
possible given the surface moisture and higher dewpoints from the
recent rainfall. Most terminals will scatter out to VFR today, but
the onshore flow may drive the stratus in longer around Humboldt
Bay. Probabilities for a return to IFR ceilings tonight are highest
for Humboldt Bay and ACV (54%). Chances lower going into Wednesday
morning with light offshore flow forecast to increase. JJW

&&

.MARINE...Northerly winds have increased across the waters behind a
frontal system. Northerly winds will increase through this afternoon
to around 20 kts, and locally higher to 25 kts in the souther waters
south of Cape Mendocino. The northerlies will pulse higher Wednesday
afternoon when winds up to 27 kts will spread over much of the
southern zones. A similar wind pattern will carry through Thursday
night before a trough from the north eases the pressure gradient and
the northerlies subside in response Friday. The northerlies will
increase behind the trough Saturday and likely into next week as
high pressure returns. A mid period WNW swell has peaked early this
morning in the 12 ft area, and this swell will continue subsiding
throughout the day. The Small Craft Advisory in the Northern Inner
zone where lighter winds persist and seas dropping below 10 ft has
been allowed to expire, while winds and seas maintain advisory
conditions elsewhere. JJW

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT early this morning for
     PZZ450.

     Small Craft Advisory until 9 PM PDT Wednesday for PZZ455-
     470-475.

&&

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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png