255
FXUS66 KEKA 211213
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
513 AM PDT Tue May 21 2024

.SYNOPSIS...Slightly below normal interior temperatures are
expected through the weekend. Gusty northwest winds will persist
today and Wednesday.

&&

.DISCUSSION...Dry weather with below normal interior temperatures
is expected for the remainder of the week and into the weekend.
Early morning temperatures varied widely from the lower to mid
30`s in a few colder valleys in Trinity, eastern Humboldt and
northern Mendocino while sites in Lake were still in the upper
60`s where N-NE winds have been steady through the night. Too much
humidity and low cloud cover tonight (Tue Night) may mitigate the
risk for frost. Drier conditions with clearer skies appear to
re-develop tomorrow night (Wed night) and frost will once again
be possible.

Slight warming is expected today for the interior; mid 70`s to
mid 80`s are forecast. Coastal areas will remain cool and blustery
and probably will not even break 60F. Wind gusts to 25-30 MPH
are forecast. Surface pressure gradients may be become disrupted
by the approach of a cold front from the NW late in the day,
however looking at the wind profiles for CEC and ACV, 1000 to 1500
feet above ground level (AGL), reveals magnitudes around 25-32kt
or 29-37mph this afternoon and early evening. GFS profiles with
height are even more robust than the NAM12, with a NW speed max
around 42-44kt or about 50 mph within 1000ft AGL. That may be a
bit hot and heavy, but that has certainly been the case with
multiple strong N-NW wind episodes this spring. HREF means are
generally around 25-30 mph for most areas, except at wind prone
coastal headlands and ridges where speeds will most likely (>70%
chance) exceed 40 mph. The wind speed max appears to shift south
of Cape Mendocino on Wednesday as weakening front brings a shallow
push of moist air and perhaps some light rain or drizzle to the
North Coast. Behind the front pressure gradients tighten again and
breezy/windy conditions return to the North Coast.

Another shortwave trough will move across the Pacific Northwest
this weekend. This reinforcing shortwave trough will keep
temperatures from warming up this weekend and may bring another
bout of breezy/windy conditions. This shortwave trough appears to
be dry too. Some coastal drizzle is possible (10% or less chance),
but not worth adding to the forecast due to high certainty at this
time. Warmer or near normal temperatures should begin to build
back on days 6-7 (Sun-Mon).

&&

.AVIATION...Light offshore winds at ACV this morning may allow for
scattered stratus to briefly develop in the Humboldt Bay area.
Otherwise, gusty northerly winds expected to develop again this
afternoon for the coastal terminals, with HREF indicating high
probability for CEC to exceed 35 mph. Mid to high level clouds
expected to drop into NorCal late this afternoon as an upper trough
progresses east. Moist NW flow ahead of a weak surface front will
encourage coastal stratus to return late tonight into early
Wednesday - light accumulating drizzle is possible at CEC and ACV
during the early morning hours. A pattern of nightly marine stratus
is possible for the ladder half of the weak as the marine layer
deepens.


&&

.MARINE...Winds will begin to diminish in the northern waters as
gales gradually shift to the southern outer waters late today.
Short period seas will remain steep and hazardous in the outer
waters through midweek, with the highest wave heights at 10-12
feet concentrated in the outer waters and lee of Cape Mendocino.
Winds and seas expected to fall near or below advisory level by
late this week as high pressure builds offshore.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Gale Warning until 3 AM PDT early this morning for Pzz450-
     455.

     Small Craft Advisory until 9 PM PDT this evening for Pzz450.

     Hazardous Seas Warning until 9 PM PDT this evening for
     Pzz450.

     Gale Warning until 9 AM PDT this morning for Pzz450.

     Small Craft Advisory from 9 AM this morning to 9 PM PDT
     this evening for PZZ470.

     Gale Warning until 9 PM PDT this evening for PZZ475.

&&

$$

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https://www.weather.gov/images/eka/zonemap.png