924
FXUS66 KEKA 302222
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
322 PM PDT Tue Apr 30 2024

.SYNOPSIS...Clearing skies inland will encourage more cold
temperatures in interior valleys overnight. Strong northerly winds,
especially along the Humboldt/Mendocino coast, will continue tonight
into Wednesday. NE flow will develop mid-week to encourage
warming and drying through Friday before potential returns for
measurable rainfall this weekend.


&&

.DISCUSSION...Broken altocumulus remains offshore this afternoon
as a surface low weakens over the PNW, leaving the CWA mostly
clear. Moist NW flow continues to moderate coastal and interior
temperatures, with current observations reading in the 50`s and
60`s following cold interior morning temperatures in the upper
20`s and 30`s. As the Pacific High builds into the PNW, the
pressure gradient will continue tightening along the coast and
enhancing northerly winds. HREF indicates that 25-35 mph winds
will stay confined to the coastal headlands of Cape Mendocino
south to Point Arena, and exposed ridges in southern Humboldt,
Mendocino and Lake counties through early Wednesday.

A cold upper trough digging into the PNW is trending east, further
minimizing precipitation impacts for NorCal. Building high pressure
subsidence will continue to usher mid to upper-level dry air into
the CWA, encouraging temperatures to drop in interior valleys
beneath clearing skies again tonight and early Wednesday morning. A
frost advisory has been issued for lower elevations in Trinity,
northern Humboldt and interior Del Norte counties, with 50-75%
NBM probabilities of <36 degrees. HREF anticipating scattered
cloud deck north of the Cape, potentially enhancing the
probability for coastal temperatures to hover around 40.

Widespread and increasingly breezy offshore (NE) flow Wednesday
will promote widespread warming and drying across the region,
especially in the interior as an inverted trough develops in the
Sac Valley. Winds are forecast to mix down and extend inland, with
25-35 mph gusts likely across Del Norte, Humboldt, Mendocino and
Lake counties and exposed ridges. RH values are currently
forecast to drop to 30% in interior Mendocino, Trinity and Lake
Counties through the remainder of the week. NBM and mid- range
models been trending cooler with <50% probabilities of
temperatures >75 degrees even in Mendocino and Lake counties.
Regardless, an overall warming trend is expected with highs in the
upper 60`s and low 70`s as the ridge builds onshore.

A broad trough axis is currently forecast to remain over the
northern rockies as several shortwaves train downstream. Another
round of minor rain accumulations is appearing more likely with
new hi-res model guidance - HREF and NBM are in better agreement
on a weak front traversing the north coast early Thursday with
potential 0.05-0.20 inches in northern Humboldt and Del Norte
counties. Looking ahead, long range cluster analyzes continue to
suggest a major change in pattern sometime early this weekend.
Members are beginning to align in the portrayal of anomalous lower
heights accompanying an upper trough Saturday - Sunday. Surface
low pressure moving through the region has potential to produce
measurable precip, although the path of this low is still very
uncertain.


&&

.AVIATION...VFR expected today (4/30) at all forecast terminals
(KACV, KCEC and KUKI). Satellite imagery is showing a layer of
broken cumulus clouds approaching from the northwest over the
coastal sites, yet this band of clouds is sitting at around 3000-
5000ft height and should have little impact on flight categories
from a ceiling height perspective. An inversion has broken this
morning allowing for northerly winds and gusts up to 25 kt at
coastal terminals (KACV and KCEC) and gusts to around 20 kt at KUKI
through the afternoon. As the solar heating begins to dissipate this
evening, winds at all sites are forecast to die down with clear
skies leading to continued VFR conditions. DS


&&

.MARINE...Winds will continue to strengthen through
Wednesday as inland California heats up creating a mesoscale thermal
low pressure system driving intense northerly flow along the coast.
Near gales with gusts to 35-40kt and large very steep combined seas
around 10 feet are forecast for the waters just south of Cape
Mendocino. These winds are strong enough to warrant a gale warning
which may even be extended as time goes on and newer model guidance
becomes available. Northerly wind gusts will probably increase again
to near gale again Wed afternoon. Thus, gale warnings are in effect
into the late afternoon/evening on Wednesday. North of Cape
Mendocino, northerly winds will increase this afternoon through
evening. Fresh to strong breezes with gusts to 25-30kt are expected
north of Cape Mendocino this afternoon through Wednesday. These
strong winds in the northern waters have caused a small craft
advisory to remain in effect until late Wednesday night. DS


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Frost Advisory from 1 AM to 11 AM PDT Wednesday for CAZ102-
     105>108.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT Thursday for PZZ450-470.

     Gale Warning until 8 PM PDT Wednesday for PZZ455-475.

&&

$$

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