Dense Fog Advisory 1, NWS Eureka, CA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
250 PM PDT Sat Apr 17 2021

.SYNOPSIS...Dry weather is forecast through most of next week. A
weak system will break through the ridge around Tuesday, resulting
in very low chances for precipitation. Temperatures across
interior valleys will be warmest on Sunday, however above normal
temperatures are forecast to occur each day next week. At the
coast, a shallow marine layer and stratus will favor much cooler
conditions through Sunday.

&&

.DISCUSSION...Interior temperatures were generally running about
5-10F degrees warmer today compared to yesterday. Daytime RH's
were also drier across the board, ranging from 10-25% this
afternoon. Thanks to a shallow marine layer and persistent
stratus, temperatures have been much cooler at the coast.

Interior temperatures will continue to warm up on Sunday, with
many valleys topping out in the 80s for highs. Also, gusty
northeast to east winds coupled with low RH's will persist through
Sunday, resulting in locally elevated fire weather conditions for
mainly the exposed ridges. Coastal sites will most likely
continue to have a steady dose of cool marine air with stratus
and fog through Sunday. High resolution model guidance suggest
rapid clearing on Sunday as the marine layer becomes shallower in
response to large scale adiabatic compression. Nearshore surface
winds do not appear favorable for any widespread stratus clearing.
A shortwave trough will approach from the NW on Monday. This s/w
trough will likely induce a deeper marine layer, with low clouds
and higher humidity pushing into the interior by Tuesday morning.

Our persistent blocking flow pattern will start to breakdown
around Tuesday as westerlies undercut the high amplitude ridge. A
shortwave trough will meander about on Tuesday and may produce
some instability for low coverage shower activity depending on
where and how this shortwave tracks. The deterministic models
were all over the place with the depth, position and progression
of this trough Tuesday through Wednesday. The EC ensemble has
been wetter than the GEFS. That bias shows up in the clusters with
92% of the EC members wetter than the mean. On the other extreme
is the GEFS with most all members dry. Forecast confidence remains
low at the moment and for now will maintain a dry forecast.

A transient 500mb trough is forecast to approach the West Coast
next weekend, bringing a chance for wetting rain (greater than
a tenth of an inch in 24 hours).

&&

.AVIATION...Pesky stratus has lingered along the coast so far today,
driving low ceilings and LIFR. Some lifting and scattering is
possible briefly this afternoon...however expect stratus to quickly
return this evening and overnight along the coast. VFR continues
across the interior, with light diurnal winds.

&&

.MARINE...Not much change in thinking as high pressure overhead
continues to promote fairly benign conditions across the coastal
waters today, with slightly higher winds and seas found near and
downwind of Cape Mendocino. Unseasonably hot temperatures over the
interior will induce a gradual tightening of the pressure gradient
through Sunday, which may produce enough of an uptick in winds to
warrant fresh advisories for the waters south of the Cape by Sunday
afternoon...latest guidance has kept these winds confined to areas
immediately south of Cape Mendocino, without the areal coverage to
warrant an advisory, so have held off on issuing anything for now. A
stronger northerly wind regime will develop over the first half of
the upcoming week as ridging breaks down overhead and is quickly
replaced by troughing over the western CONUS and rebuilding high
pressure farther offshore.

&&

.FIRE WEATHER...East winds gusting from 10 to 30 mph will be
possible across exposed ridges through Sunday. In addition, warm
temperatures and poor overnight humidity recoveries will occur at
ridgetop level. Those conditions combined with below normal
rainfall and seasonably dry vegetation will aid in an elevated
fire weather threat.

Garner

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...None.
&&

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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
300 AM PDT Sat Apr 17 2021

CAZ101>115-181000-
Coastal Del Norte-Del Norte Interior-Northern Humboldt Coast-
Southwestern Humboldt-Northern Humboldt Interior-
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-
300 AM PDT Sat Apr 17 2021

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...Sunday through Friday.

No hazardous weather is expected at this time.

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