Helena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

103
FXUS66 KEKA 202248
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
348 PM PDT Fri Sep 20 2024

.SYNOPSIS...Dry and warming trend is expected this weekend, with
interior hot temperatures early next week. Breezy north-
northwesterly winds along the coast through this evening, with
gusty offshore flow over the interior ridges into Saturday
morning.


&&

.DISCUSSION...High pressure offshore will continue to build over
the West Coast during the next 24 hours. Pics from the sky depict
mostly sunny across the forecast area, with the exception of
lingering stratus along the Mendocino Coast. Breezy north-
northwest have developed this afternoon with a thermal trough near
the coast. Gust from 30 to 40 mph are already observed over the
coastal headlands north of Cape Mendocino. North-northwest winds
are expected to diminish this evening. Meanwhile, offshore flow
continue developing this afternoon and increase later this evening
over the exposed ridges, especially in Del Norte, Northeastern
Humboldt and Lake County where gusts from 25 to 35 mph are likely.
This drier offshore airmass will promote low humidity across the
area. See Fire Weather Section for more details. Offshore winds
will yield clear skies along much the coast late tonight and
through the weekend.

The ridge will slowly amplify this weekend with a 850 mb
temperatures warming through early next week. Temperatures will
peak early next week when the warmer inland valley temperatures
reach into the upper 90s into 100. These temperatures will be 10
to up to nearly 15 degrees above normal and will bring areas of
Moderate Heat Risk Monday and Tuesday.

Ensembles and deterministic models suggest the upper level ridge
shifting eastward on Tuesday as an upper level trough approaches
from northwest, while, a surface cyclonic circulation approaches
from south along the coast. This surface low will bring a
southerly reversal stratus surge Tuesday evening into Wednesday
morning, with low clouds and patchy fog charging up and lapping
the coastal areas. This will bring a push of marine air to the
interior on Wednesday. Some cooling is expected on Wednesday, but
high temps will remain above normal through the end of the week.


&&

.AVIATION...Elevated winds from the N to NE are creating notable low
level wind shear today. These winds will increase tonight with 30 to
35 kt winds down to 1500 to 2000 ft AGL. This threat will linger
longer in Del Norte County Saturday where NE winds aloft will be
stronger. The shallow stratus has scattered out this afternoon. The
increased northerly winds this afternoon followed by a descent
nocturnal offshore push will greatly limit stratus formation. NBM is
maintaining an around 40% chance for a return of LIFR CIGS tonight
around Humboldt Bay and into ACV. HREF holds lower chances, around
20%. VFR conditions are anticipated elsewhere.


&&

.MARINE...Gale strength northerlies with gusts up to 40 kts have
developed over the waters. These winds have the highest coverage
over the outer waters, but gale conditions will intrude the inners
around Cape Mendocino and Point St George. In response to the winds,
seas will continue to build to 14 ft at 10 seconds by this evening.
These very steep and hazardous seas will propagate into the inner
zones this evening and into midday Saturday. A Hazardous Seas
Warning is out for the Northern Inner zone 450. Winds and seas will
be very slow to subside on Saturday.


&&

.FIRE WEATHER...Breezy offshore flow will continue to developed
and increase over the higher terrain in Del Norte, northeastern
Humboldt and eastern Lake counties this afternoon and evening.
Low daytime humidity with values from 15 to 25 percent are
occurring across the interior this afternoon. Drier offshore
airmass will promote poor RH overnight recoveries on Saturday
morning. Elevated to locally critical conditions are expected
tonight into Saturday due to gusty northeasterly winds and poor RH
recoveries over the higher terrain in zones 203, 204, and 264.
Winds are expected to diminish later Saturday morning. Winds will
shift to west-northwest across the southern portion of the area
Saturday afternoon. Temperatures in the upper 90`s into 100, low
humidity and gusty offshore winds will promote critical fire
weather conditions Monday and Tuesday.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT this evening for PZZ450.

     Hazardous Seas Warning from 9 PM this evening to 9 AM PDT
     Saturday for PZZ450.

     Small Craft Advisory until 9 AM PDT Saturday for PZZ455.

     Gale Warning until 9 AM PDT Saturday for PZZ470-475.

&&

$$

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