899
FXUS66 KEKA 201106
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
406 AM PDT Mon May 20 2024

.SYNOPSIS...Slightly below normal temperatures expected through the
week amidst a series of upper shortwaves and associated weak fronts.
Strong coastal pressure gradient will reinforce gusty NW winds
through Tuesday. Weaker winds and moisture advection may allow coastal
stratus to redevelop in the second half of the week before
potential for a more unsettled pattern into next weekend.

&&

.DISCUSSION...Temperatures are quickly cooling this morning beneath
clear skies as an upper trough settles over the PNW - a frost
advisory is currently in effect for isolated portions of interior
Humboldt and western Trinity counties amidst a dry and well-mixed
BL. Although advisory criteria is limited, temperatures near or <40
degrees are becoming more widespread from interior Del Norte to
northern Mendocino counties.

A strong pressure gradient between the terrestrial thermal trough
and offshore high pressure will continue to produce gusty northerly
winds for the start to this week. Gusts 20 to 30 mph are still
apparent on the northern Del Norte coast following advisory winds
yesterday afternoon. Winds expected to ramp up again across the CWA
late this morning as the coastal jet pushes onshore - HREF indicates
>75% probabilities for gusts exceeding 40 mph, especially along the
coastlines of Humboldt, Del Norte and Mendocino counties as well as
exposed headlands along Cape Mendocino. Interior ridges also likely
to exceed 20 mph.

Mid to high level cloud cover will accompany a series of weak
troughs progressing through the region beginning late Tuesday.
Cooling aloft alongside strong winds should keep coastal stratus to
a minimum through Tuesday, after which the wind field is likely to
shift into the southern waters and further offshore. More persistent
WNW flow is forecast by mid-week, enhancing BL moisture and allowing
for potential redevelopment of the marine inversion as a transient
ridge builds into the coast. Long range models indicate a more
progressive troughing pattern expected for late this weekend into
next weekend.



&&

.AVIATION... Weakening marine layer and strong northerly winds will
contribute to VFR conditions at the coastal terminals today,
although scattered stratus may develop around ACV prior to sunrise
while winds are calm. Hi-res models indicate high probability for
CEC and ACV to see gusts exceeding 40 mph this afternoon as the
coastal jet pushes onshore. NW flow expected to produce gusts
exceeding 20 mph in UKI afternoon with daytime heating. Winds
forecast to diminish and shift offshore Monday night into Tuesday as
the coastal pressure gradient slackens, allowing potential for
more marine stratus to develop.


&&

.MARINE...A thermal trough along the coast continues to produce a
strong pressure gradient that will persist through Monday
evening. As a result, northerly gales are expected in all zones
through Monday, producing hazardous 10-12 foot short period waves
across all zones. Steep and dangerous seas will continue into
early next week as gales persist. Significant wave heights to 15
feet at 10-11 seconds are expected. Current model guidance
indicates the strongest winds and wave response shifting to the
southern waters by Tuesday. Gales are expected to finally cease by
mid week as the coastal pressure gradient weakens, but a small
craft advisory may be warranted for the middle to end of the week.



&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Frost Advisory until 9 AM PDT this morning for CAZ106-108.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Gale Warning until 9 PM PDT this evening for PZZ450-455.

     Gale Warning until 4 AM PDT Tuesday for PZZ470.

     Gale Warning until 10 AM PDT Tuesday for PZZ475.

&&

$$

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