950
FXUS66 KEKA 012205
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
305 PM PDT Sat Jun 1 2024

.SYNOPSIS...A very late season atmospheric river will bring light
rain to the North Coast Sunday afternoon through Monday morning.
Heat will quickly build back in by mid next week with interior highs
over 100 degrees.



&&

.DISCUSSION...Largely seasonable weather has persisted today under
the influence of weakening high pressure. Skies have been mostly
clear allowing the interior to warm into the 80s. Meanwhile a gentle
sea breeze has kept the coast cool mostly below 60. All that said,
high clouds are apparent on satellite spreading across the area, the
first sign of an approaching upper level trough.

More high clouds and moisture will continue to stream into the area
tomorrow as a late season atmospheric river travels south down along
the coast. This stream of moisture will bring light rain all along
the coast tomorrow afternoon through Monday morning. Rain will be
strongest in the terrain of Del Norte where south facing slopes will
bear the highest rain rates. Most likely rainfall over the 24 hour
period ranges from 0.7 to 1.7 inches along the highest terrain. Even
Around Humboldt Bay, 0.2 to 0.5 inches is most likely. More minor
wetting rain of 0.1 to 0.2 inches is most likely in Trinity and
along the Mendocino coast through early Monday afternoon with only
trace amounts for the more southern interior. Despite the time of
year, the system has a very winter time profile with very little
surface instability, so any thunderstorms even over high terrain is
very unlikely (< 5% chance). ECMWF EFI highlights how unusual such
rain is for June, even for Del Norte County where it is highlighted
above the 90th percentile for climatology. That said, impacts will
generally be minor with debris on roadways and slipperiness from oil
buildup will be the main concerns.

Rain and clouds will help cool interior temperatures into the 70s
for Monday, but such cool conditions will be very short lived. There
is very high confidence that high pressure will rapidly build across
northern California mid next week, brining the hottest temperatures
of the year so far. For the valleys of Mendocino and especially Lake
Counties, NBM is already showing a 60 to 80% chance of highs above
100 next Wednesday and Thursday. Though not quite record breaking,
such conditions will bring the first high heat risk of the year,
especially across Lake County where influence from the central
valley could help keep even overnight temperatures as high as 70.
/JHW


&&

.AVIATION...18Z TAF
ACV/CEC...VFR conditions prevail this afternoon with dissolved
stratus. A weak shortwave trough will move through tonight to
increase low clouds and some coastal drizzle. Ceilings will
generally lower tonight to MVFR levels. CEC will have the best shot
of light drizzle, and these conditions would lead to lower VIS and
perhaps dips into LIFR (25%) earlier. A deepening marine layer
should lead to higher CIGS. Rainfall chances will increase
throughout the day Sunday as a late season Pacific low pressure
system nears the region.



UKI....Firmly VFR with NW wind gusts to ease this evening. A jet of
NW winds aloft of up to 35 kts will create low level wind shear
through 10Z Sunday. Stratus will build in from the west into the
high terrain with deepening from a weak shortwave trough, but
soundings indicate the depth will not be enough to near the valley.
/JJW


&&

.MARINE...Northerly winds and seas have eased in the northern
waters, and are also quickly subsiding in the souther zones. On
Sunday, seas will drop range from 3 to 5 feet with the arrival of a
small, period NW swell at around 3-4 ft at 10 seconds. Winds will be
light, up to 12 kts and split in flow. Southerly winds will increase
Sunday night through Monday morning ahead of a trough.

On Monday, a slightly larger, mid period NW swell will move in,
building to around 8 ft at 10 seconds early Tuesday morning. Light,
split wind flow will transition to light northerly winds Monday.
These winds will slowly increase in the southerly zones, initially
south of the cape.

Tuesday, the NW swell will hold in size, then slowly lowering late
in the day. A larger reinforcing swell then move in. Northerly winds
in the southern waters will further increase, exceeding 22 kts south
of the cape in the afternoon.

On Wednesday, a seasonably large, longer period WNW swell (300
degrees) will build in, currently forecast up to around 12 ft at 14
seconds. Northerly winds will be on the increase throughout the day,
with gale conditions probable by late Wednesday. /JJW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Excessive Heat Watch from Tuesday morning through Thursday
     evening for CAZ114-115.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 11 PM PDT this evening for
     PZZ455-475.

&&

$$

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