316
FXUS66 KEKA 212118
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
218 PM PDT Fri Mar 21 2025

.SYNOPSIS...Wet weather continues for Humboldt and Del Norte
counties through Saturday. Drier and warmer weather forecast Sunday
into early next week. Wet weather returns mid to late next week.

&&

.DISCUSSION...

KEY MESSAGES:

* Weak atmospheric river system continues to impact the region
  through Saturday.

* Dry weather expected Sunday through Tuesday, with well above
  normal temperatures expected.

* Wet weather likely to return in the middle of next week.

WEATHER PATTERN OVERVIEW: An atmospheric river is aimed toward the
Pacific Northwest today. This dropped slightly south to bring some
rain to Humboldt and Del Norte counties. This afternoon and
tonight this starts to move north as high pressure builds in and
rain will diminish tonight and Saturday. High pressure continues
to build in Sunday and Monday bringing warm and dry weather to the
area. Significant warming is expected on Monday bringing highs
into the low 80s in the warmer valleys. Sunday morning will
likely see widespread valley fog and to a lesser extent Monday and
likely very little by Tuesday. At the coast there may be some
stratus, with increasing likelihood by Tuesday.

Wet weather is expected to return at some point on Wednesday or
Wednesday night and continuing on Thursday. This looks like it
will bring rain to the area, but at this point it looks like there
won`t heavy rain or flooding.

FORECAST CONFIDENCE AND DEVIATIONS: Tonight and Saturday the
pattern is fairly benign with rainfall ending through the day
Saturday. The HREF mean shows the rain ending around 2pm in
Crescent City, 11am in Eureka, and any lingering rain in northern
Mendocino county ending by 5am. Saturday night temperatures may be
warmer than forecast due to widespread fog across the valleys.
This fog will diminish each night and allow for better radiational
cooling. This however will come at the same time as significant
warm air advection. So frost will be possible Monday morning, but
not too likely. High temperatures will continue to warm with a 70
percent chance of exceeding 85 degrees by Monday afternoon in
Ukiah. This drops to 50 percent by Tuesday.

Wednesday at some point later in the day rain is expected to
return. For the period Wednesday night and Thursday there is a 30
to 60 percent chance of exceeding 1 inch in the higher terrain of
Humboldt, Del Norte and Trinity counties and northern Mendocino
county. These probabilities decrease rapidly farther south into
southern Mendocino and Lake counties. Probabilities for snow are
mainly over the higher terrain, but this will need to be watched
as it gets closer.

Late in the month the ensembles are starting to show increased IVT
highlighting the potential for possible heavy rain. There is still
a lot of uncertainty on the timing of this, but a growing number
of ensemble members are this. MKK

&&

.AVIATION...Persistent light rain has largely maintained MVFR
conditions across the area today. Ceilings have gradually lowered
as high pressure building to the west has increasingly trapped
moisture closer to the surface. Weakening wind and building
pressure will continue this process overnight, helping to generate
IFR (85% chance) and even short periods of LIFR (25% chance)
ceilings and visibilities mostly along the immediate coast.
Conditions will remain clearer inland and south of Cape Mendocino.
Marine influence will most likely remain strong through tomorrow
afternoon near the coast with much clearer conditions inland. /JHW

&&

.MARINE...A slight increase in swell energy has brings small craft
advisory conditions into the southern inner and outers to join the
northern inner and outer waters, at least through this evening.
Steep square waves continue at 10-12 feet and longer mid periods at
12-14 seconds. These conditions will ease a bit as wave heights come
down by Saturday afternoon at 8-9 feet with periods remaining around
12 seconds. Winds have already picked up near the north buoys at
Crescent City, around 25 kts. This will further enhance wave action
until southerly winds ease later tonight behind the passing front.
Winds will turn to out of the north as ridging builds aloft into the
first part of next week. A long period westerly swell will build
into the waters late Saturday into Sunday bringing a slightly
increased shoaling threat but remaining the overall sea state below
10 feet.

&&

.BEACH HAZARDS...A longer period swell will build into the waters
over the weekend bringing a moderate sneaker wave threat. At this
time the swell looks to have a period around 15-17 seconds, which
isn`t an extremely long period, but is still long enough to allow
for set behavior to develop. A beach hazard statement has been
hoisted for Sunday morning through Sunday evening. An additional
sneaker wave threat is likely Monday evening as a fresh NW swell
arrives during the decay of the previous swell train.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 9 PM PDT this evening for PZZ450-
     455-470-475.

&&

$$

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