Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 011237

National Weather Service Eureka CA
437 AM PST Mon Mar 1 2021

.SYNOPSIS...Dry weather and near-normal temperatures will occur
across northwest California through Wednesday. Precipitation
chances will then increase Thursday into the weekend.


.DISCUSSION...An upper trough was in the process of digging
southward over the NERN PAC early this morning. Downstream from
that feature, weak and variable winds were beginning to
transition to southerly in response to a surface frontal boundary
approaching from the west. Marine stratus was also fairly
widespread near and west of the immediate coast. As the day
progresses, the previously mentioned trough to the west is
forecast to evolve into a closed upper low. That low will then dig
south away from NWRN CA. Dry weather will be probable as a result.
In addition, a period of gusty south-southeast winds is forecast
to develop this afternoon and persist into part of the night.
Downslope winds in the vicinity of Humboldt Bay will aid in
boosting afternoon highs into the upper 50s to near 60. Elsewhere,
near-normal temperatures appear likely.

The only short-term hazard expected at this time will be areas of
frost and freezing temperatures across most inland valleys this
morning, and again Tuesday morning. Reference the latest frost and
freeze products for additional information. Otherwise, dry
weather is forecast to persist through mid week. Thereafter, model
guidance shows a cold upper trough digging over the NERN PAC
Thursday, and then ejecting eastward across the West Coast Friday
and Saturday. A period of moderate to locally heavy frontal rain
will be possible Friday afternoon and evening. Furthermore, pre-
frontal advisory level southerlies may occur across exposed ridges
and coastal areas Friday morning. Light mountain snow also
appears possible during Saturday as a cold post-frontal midlevel
airmass spreads east across the region.



.AVIATION...Stratus has formed offshore overnight, with a surge
bringing IFR to MVFR ceilings to much of the coastline north of
Trinidad and patches of stratus around the Humboldt Bay region
early this morning. At time of writing, another surge has formed
in an eddy to the south of Cape Mendocino, and is nearing the Lost
Coast and Mendocino Coastline...this will likely soon move
onshore and linger through much of today.

Light offshore southeasterlies are expected to clear out most the
Redwood Coast around daybreak, although stratus will likely
remain near the coast for most of today. Southerly winds around
Cape Mendocino may advect stratus around the Cape later this
morning...potentially bringing MVFR to IFR ceilings to KACV
sometime in the early afternoon. Light offshores are expected to
develop again tonight, likely eroding any low clouds for most
areas...although a few protected valleys may see patchy fog
development and a some low clouds may linger in the Humboldt
Bay/Eel river delta region.


.MARINE...Relatively benign marine conditions prevail today for
most of the waters, although some localized gusty southwesterly
winds may briefly develop just to the north of both Pt Arena and
Cape Mendocino this afternoon, then weaken around sunset. Seas
today remain dominated by a mid period NW swell around 6 to 8 ft.
This will be reinforced tonight and Tuesday by another mid period
NW swell, peaking Tuesday night around 11 ft at 14 seconds. Light
northerly winds should return for Tuesday and Wednesday, and
latest guidance continues to trend toward these remaining well
below advisory levels...topping out around 10 to 15 kts in the
outer waters and lighter nearshore.

A front is expected to approach the coast late this week,
bringing robust southerly winds starting Thursday and possibly
lasting into the weekend. Should this occur, it could whip up
short period southerly seas with heights in the low to mid teens.
Meanwhile, another slightly longer period 10 to 12 ft NW swell
should arrive late this week, bringing a chance of chaotic
combined seas in the high teens for Friday.


CA...Frost Advisory until 8 AM PST this morning for CAZ110-113-115.

     Freeze Warning until 8 AM PST this morning for CAZ111-114.



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