Frost Advisory 14, NWS Eureka, CA

032 
WWUS76 KEKA 191539
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
839 AM PDT Wed Apr 19 2023

CAZ110>115-191645-
/O.EXP.KEKA.FR.Y.0014.000000T0000Z-230419T1600Z/
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-Southeastern Mendocino Interior-
Northern Lake-Southern Lake-
839 AM PDT Wed Apr 19 2023

...FROST ADVISORY WILL EXPIRE AT 9 AM PDT THIS MORNING...


$$

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
252 PM PDT Tue Apr 18 2023

.SYNOPSIS...Modest showers will tapper off late this evening with
light snow above 2500 feet. Cloudy, cool weather will continue
through mid week with warm and dry weather this weekend.

&&

.DISCUSSION...A negatively tilted trough over the area has
continued to progress to the east today with scattered showers
continuing along coast. Little to no additional precipitation has
been measured as of 1400, though that will likely change this
evening. Radar shows a number of growing shower bands offshore. No
lightning has been observed yet, but with around 100 J/Kg of CAPE
and lingering cold air will make isolated lightning possible this
evening. That said, instability is just a fraction of what was
observed yesterday, so a similar squall line is very unlikely. up to
additional 0.2 and 1.0 inches of rain is forecast along the Humboldt
and Del Norte coasts with only a trace amount of rain expected
anywhere else.

Lingering cool air tonight will again allow snow level to drop near
2000 feet, though weaker wind will limit any kind of localized
dynamical cooling. Snowfall will be limited by the weaker mixing of
cold air to the surface and generally meager QPF. Another dusting of
snow is likely along Berry Summit but overall accumulation will be
minimal. Impactful snow is mostly likely near Collier Tunnel where
an additional 1 to 3 inches is expected late this evening. Cold air
advection continuing will bring near to below freezing low
temperatures tonight. HREF shows a 75% chance or higher of low
temperatures below 36 throughout the area. That said, cloudy skies
will likely inhibit surface cooling that would generate widespread
frost. Similarly, winds will likely inhibit frost where skies are
clear in Lake County. SOuthern Mendocino has the highest chance of
frost formation but uncertainty remains too high to issue any kind
of product there with extensive cloud cover remaining visible on
satellite.

Ridging will begin to building heading later into the week. As cold
air lingers but skies clear, widespread frost will become
increasingly likely especially in central and southern Mendocino
County. Though instability will likely keep the northern half of the
area cloudy into Wednesday. As we head into the weekend, increasingly
strong ridging will bring hot, dry, and almost summer like
conditions, especially for inland areas. Highs will approach the
upper 70s and 80 by Saturday. Though ridging is not likely to last
long with essentially all models showing disturbances and light rain
sometime early next week. /JHW

&&

.AVIATION...Waves of scattered showers (and perhaps a few more
embedded thunderstorms) will move inland into Wednesday, mainly near
and N of Cape Mendocino. As a result, latest TAF package fluctuates
between prevailing showers and vicinity showers based on the latest
high resolution model data. Visibility reductions should mostly be
in the MVFR range, although brief periods of IFR are not out of the
question in both heavier rain showers and small hail showers. Shower
chances will gradually wind down during the day Wednesday. Low
ceiling heights are expected to gradually fall through the night,
but cloud cover will fluctuate between scattered and near overcast.
Some patchy fog will also be possible, but impacts will be reduced
by continued low-level instability. Gusty S-SW winds along the North
Coast will gradually diminish through the evening hours. /SEC

&&

.MARINE...Southerly winds will gradually diminish this evening.
Large NW swell will continue to bring advisory-level seas tonight.
Seas will be a bit slower to subside. Have extended the Small Craft
Advisory over the S waters through 3 AM Wednesday morning to account
for lingering combined seas near 10 feet. Winds will become
northerly and increase by late Thursday and continue into the first
half of the weekend, with near advisory level speeds in the southern
outer waters. /SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Winter Weather Advisory until 9 AM PDT Wednesday for CAZ102.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until midnight PDT tonight for PZZ450-
     470.

     Small Craft Advisory until 3 AM PDT Wednesday for PZZ455-
     475.

&&

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

Hazardous Weather Outlook
National Weather Service Eureka CA
307 PM PDT Tue Apr 18 2023

CAZ101-103-104-106>115-192215-
Coastal Del Norte-Northern Humboldt Coast-Southwestern Humboldt-
Southern Humboldt Interior-Northern Trinity-Southern Trinity-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Southwestern Mendocino Interior-
Southeastern Mendocino Interior-Northern Lake-Southern Lake-
307 PM PDT Tue Apr 18 2023

This hazardous weather outlook is for northwest California.

.DAY ONE...This afternoon and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected at this time.

CAZ102-105-192215-
Del Norte Interior-Northern Humboldt Interior-
307 PM PDT Tue Apr 18 2023

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 9 AM PDT WEDNESDAY...

This hazardous weather outlook is for northwest California.

.DAY ONE...This afternoon and tonight.

A Winter Weather Advisory is currently in effect.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

A Winter Weather Advisory is currently in effect.

.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected at this time.