345
FXUS66 KEKA 231122
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
422 AM PDT Mon Sep 23 2024

.SYNOPSIS...Key messages include climatologically warm temperatures
for today and Tuesday, with a return to cooler and more typical
temperatures for this time of year for Wednesday with drizzle along
the coast (mainly Del Norte/Humboldt Counties). Also wind speeds and
gusts will be on the higher side, climatologically toward Del Norte
County as well as over the waters (especially north).


&&

.DISCUSSION...Overall synoptic pattern continues with an anomalously
amplified upper ridge dominating the area, with the axis crossing
the area by tonight, allowing for a bit cooler temps for Tuesday,
and considerably cooler Wednesday as an upper trough moves in,
combining with a closed low off of southern California. Ensemble
data reveals that the biggest climatological anomaly for surface
temperatures will be over the coast (although some interior valleys
could hit toasty temps above 100 degrees). Along the coast in
Crescent City, there is a 50 percent chance of high temperatures
between 70 and 74 degrees, with the NBM deterministic solution
coming in at 68 degrees (average high is 64 degrees). With a
calibrated probability of 90% chance of 68 degrees or more at KCEC,
it would be a safe bet to bump this up to lower 70s, with a 75%
chance of 70 or more. At Arcata, there is a 60% chance of at least
74 degrees for a high temperature. However, we are not anticipating
a record breaking event (record is 82), as we stand a 0% chance of
77 degrees or more, according to NBM, as NBM also indicates that
offshore flow will generally be not particularly strong and onshore
breezes are advertised to kick in by late morning or early
afternoon.

Also wind speeds toward Del Norte County will be relatively strong,
thanks mostly to an increased surface pressure gradient. Little
spread in solutions reveal that confidence is high for wind gusts.
Mean max wind speeds and gusts are 17 and 30 mph respectively. To
get closer to the wind/wind gust solutions suggested by calibrated
probabilities in the short term, HiRESWarw was used in conjunction
with the mean NBM solution for period 1 afternoon winds/wind gusts
over the land with wind gust multipliers near 1.55 this afternoon,
giving Crescent City wind gusts pushing 30 mph from the northwest
this afternoon.

With the incoming upper trough, NBM indicates coastal
stratus/drizzle returning Wednesday (mainly Del Norte and Humboldt
Counties), with a near 100% chance of sky cover over Crescent City
by around 2PM Wednesday, with a 50 percent chance of accumulating
drizzle at some point in the afternoon or evening. There will also
be a near 100% chance of cloudy conditions occurring with about a 20
percent chance of accumulating drizzle in Arcata (ACV), but this
drops off to the south. /MH


&&

.AVIATION...Clear skies are forecast to continue at all terminals
through much of this TAF period. Stratus and fog will continue to
result in LIFR cigs and vsbys along parts of the Mendocino coast
through Monday. Only patchy stratus and fog is expected around
Humboldt Bay/Eel Delta with less than a 20% chance for LIFR at
KACV from 14Z to 18Z today. Update coming by 12Z. DB/MH


&&

.MARINE...Near gale conditions with occasional gusts to around 35
kt and large steep northerly wind waves near 10 feet are forecast to
continue in the outer waters through today. Steep wind waves will
also propagate into the inner waters today, primarily in the
northern inners. Northerly conditions will ease tonight and then lay
down more substantially on Tuesday and Wednesday as the thermal
trough weakens and shifts inland. A series of mid period NW swell
will build early next week, peaking around to around 8 ft on Wed.
Potential for gale force northerlies and large steep waves over 10
feet will increase Fri-Sat. DB


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 AM PDT this morning for PZZ450-
     455.

     Small Craft Advisory until 9 AM PDT Tuesday for PZZ470.

     Small Craft Advisory until 3 AM PDT Tuesday for PZZ475.

&&

$$

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