Winter Storm Watch 9, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
458 AM PDT Fri Mar 24 2023

.SYNOPSIS...Unseasonably cold temperatures and a chance for
light rain and snow showers will persist Friday through Sunday. A
strong Pacific cyclone is projected to impact the area with strong
winds, heavy rain and heavy mountain snow Monday and Tuesday.
Drier weather is expected for mid to late in the week.

&&

.DISCUSSION...An upper level trough north of the area is slowly
moving off to the east, but is still bringing some showers to
the area. A subtle shortwave moving through the flow is expected
to bring a period of heavier showers this morning. Snow levels
linger around 2,000 feet for these showers, so have extended the
winter weather advisory in northern Humboldt and Del Norte
counties to highlight this. Humboldt and Del Norte counties will
continue to see a few isolated showers over the weekend, but there
is not expected to be enough snow for a winter weather advisory.
Temperatures will be unseasonably cold, especially in Mendocino
and Lake counties where skies will be the most clear. The freeze
warning and frost advisory are on track this morning. Have issued
a freeze watch for Mendocino and Lake counties for Saturday
morning. Northeastern Mendocino and northern Lake may see
temperatures drop below 29 and need a hard freeze warning, but
held off on that for now. The coast may end up needing only a
frost advisory, but this will need to looked at it again later
today. The coldest night will likely be Sunday morning across
much of the area with the colder spots dropping into the mid 20s
if they remain clear. The Humboldt and Del Norte coasts may some
frost Saturday morning, but held off on issuing anything as there
will be some showers around that may keep things mixed enough to
limit temperatures in the mid 30s.

After the weekend all eyes turn toward the large upper level low
and strong frontal boundary moving towards the area on Monday.
The overall agreement is fairly good with this system, but the
details continue to be slightly fuzzy. The models trended slightly
farther south with it on the 00Z runs of the models. This lowered
the QPF, but brought in colder air. Snow levels look to be around
2500 feet or possibly lower at some points. This has the
potential to bring some very heavy snow in eastern Trinity county
again. 1 to 2 feet is possible near Trinity Lake with the current
forecast scenario. Humboldt and Del Norte counties will see heavy
snow as well, but it will be right around 2500 to 3000 feet and
may not impact the major highway passes. Mendocino and Lake
counties will likely not see it impact the major highway
corridors, but the rural areas above 3000 feet will likely see
over a foot of snow. This will bring rapid rises on the rivers of
Mendocino county, but probabilities of the Russian an Navarro
rivers remains low. Strong winds are also expected with this
system. The GFS is currently showing 850mb winds of 65 kt over
Cape Mendocino. As it gets closer the details will become clearer
in the high resolution models.

Mid to late in the week the models are in disagreement in how
quickly a ridge will build into the area. Some of the ensemble
clusters have a ridge over the area and dry weather Thursday and
Friday. The other solution shows the trough lingering and allowing
some light rain or snow showers to continue. Either way
temperatures are expected to remain below normal. MKK

&&

.AVIATION...Light rain showers persist at the coastal terminals
through the morning. Flight categories will hover around VFR with
southerly winds transitioning NW by the afternoon. Gusts up to 20 kt
by the late afternoon will be short lived. Ceilings around 4000 to
5000 feet will be mostly overcast. Most of the showers will remain
in the northern portion of the CWA, KUKI will get high cloud groups
by the afternoon yet remain in VFR. /EYS

&&

.MARINE....Northwesterly winds continue in the outer waters
around 20 kt and will ease in the northern outer waters by
evening. Small craft advisories are in place for all area waters
as swell and elevated winds will make seas hazardous for smaller
vessels. A northwesterly swell approaching 15 feet at 14 seconds
will fill in by evening and last into the weekend, diminishing by
Sunday afternoon. Strong southerlies are expected early next week
as as a cold upper level trough dives down to our area. /EYS

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Winter Weather Advisory until 2 PM PDT this afternoon for
     CAZ102-105.

     Winter Weather Advisory until 8 AM PDT this morning for
     CAZ106.

     Freeze Watch from late tonight through Saturday morning for
     CAZ109>115.

     Freeze Warning until 9 AM PDT this morning for CAZ110-111-
     114-115.

     Frost Advisory until 9 AM PDT this morning for CAZ112-113.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Sunday for PZZ450-455-
     470-475.

&&

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Hazardous Weather Outlook
National Weather Service Eureka CA
401 AM PDT Fri Mar 24 2023

CAZ101-103-104-251115-
Coastal Del Norte-Northern Humboldt Coast-Southwestern Humboldt-
401 AM PDT Fri Mar 24 2023

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

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

CAZ112-113-251115-
Southwestern Mendocino Interior-Southeastern Mendocino Interior-
401 AM PDT Fri Mar 24 2023

...FROST ADVISORY IN EFFECT UNTIL 9 AM PDT THIS MORNING...
...FREEZE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SATURDAY
MORNING...

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

A Frost Advisory is currently in effect.
A Freeze Watch is currently in effect.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

A Freeze Watch is currently in effect.

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

CAZ102-105-251115-
Del Norte Interior-Northern Humboldt Interior-
401 AM PDT Fri Mar 24 2023

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 2 PM PDT THIS AFTERNOON...

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

A Winter Weather Advisory is currently in effect.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Heavy snow is possible above 2500 feet Monday and Tuesday.

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

CAZ110-111-114-115-251115-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-Southern Lake-
401 AM PDT Fri Mar 24 2023

...FREEZE WARNING IN EFFECT UNTIL 9 AM PDT THIS MORNING...
...FREEZE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SATURDAY
MORNING...

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

A Freeze Warning is currently in effect.
A Freeze Watch is currently in effect.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

A Freeze Watch is currently in effect.

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

CAZ106-251115-
Southern Humboldt Interior-
401 AM PDT Fri Mar 24 2023

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 8 AM PDT THIS MORNING...

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

A Winter Weather Advisory is currently in effect.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

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

CAZ109-251115-
Mendocino Coast-
401 AM PDT Fri Mar 24 2023

...FREEZE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SATURDAY
MORNING...

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

A Freeze Watch is currently in effect.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

A Freeze Watch is currently in effect.

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

CAZ107-108-251115-
Northern Trinity-Southern Trinity-
401 AM PDT Fri Mar 24 2023

This hazardous weather outlook is for northwest California.

.DAY ONE...Today and tonight.

No hazardous weather is expected through tonight.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Heavy snow is possible above 2500 feet Monday and Tuesday.

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