Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 121048
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
348 AM PDT Tue Mar 12 2024

.SYNOPSIS...Lingering showers today will lead to warmer and drier
conditions late this week. Higher NE winds in Lake county are likely
on Thursday. Highs in the 60`s and 70`s are likely through the
weekend with no major disturbances appearing until mid next week.


&&

.DISCUSSION...The axis of an upper level trough will continue
traversing the PNW, lending strength to lingering frontal showers
across the CWA. Additional precipitation amounts are expected to be
light - both NBM and HREF have 80-90% probabilities of greater than
0.25 inches by 5PM this evening. Similarly, with snow levels rising
over 5,000 ft in the warm sector of this frontal boundary,
minimal accumulations are expected in the highest elevations.
Winds will remain breezy through this evening as they turn NNW and
diminish through Tuesday evening.

The North Pacific High will quickly build into the west coast by
Wednesday as an upper level low becomes cutoff over the desert
southwest. North winds are expected to increase again as the
pressure gradient along the CA coast intensifies, especially
offshore south of Cape Mendocino. An inverted trough extending from
the low over AZ/SoCal will extend into the Sacramento Valley by
early Thursday and tighten the thermal gradient further, allowing
strong NE winds to develop in southern Mendocino and Lake County. A
wind advisory may be required as temperatures warm and RH values
decrease below 50%.

Meanwhile, a warm airmass extending through the high pressure ridge
will generate robust WAA across the entire PNW late this week with
strong easterly downslope warming. NBM is indicating a high
probability of coastal temperatures exceeding 60 degrees on
Thursday, while interior valleys reach into the mid to upper 60`s.
EFI (Extreme Forecast Index) has been consistently highlighting
exceptional max daytime temperatures for Friday and Saturday in
particular - long range deterministic models and NBM guidance have
temperatures reaching 65 along the coasts and into the low 70`s for
interior valleys.

Long range cluster ensembles have persistent ridging over the region
through mid next week, where models begin to diverge into potential
for a change in pattern.


&&

.AVIATION...Moist NW-W flow associated with an upper trough
will yield occasional MVFR ceilings (1500-2500 ft) and scattered
showers today. Brief vsby obscuration (2-3SM) in light showers will
be possible. Shower activity and potential for MVFR ceiling will
diminish this evening as the trough lifts out to the northeast and
upper ridging builds offshore. Some mist and shallow low clouds
possible overnight, especially for inland valleys. Confidence is not
high KUKI will get fog or low IFR ceilings tonight, however. DB


&&

.MARINE...Elevated westerly swell (10-12ft at 13 sec) will continue
today as winds shift around to the west-northwest behind a frontal
system. Northerly winds are forecast to return tonight and then
increase to 15 to 25 kt on Wednesday. A brief northerly gale with
gusts to 35-40kt is probable in the lee of Cape Mendocino late Wed
afternoon into evening. A reinforcing westerly swell will build to
13-15 ft tonight and persist on Wednesday as steeper northerly waves
build to 4 to 7 ft by Wednesday evening. Axis of strongest
northerlies shift into the outer waters on Thu and Fri as an
inverted trough develops and a prevailing easterly wind flow regime
unfolds nearshore. Longer period westerly swells are forecast to
arrive toward the end of the week. As short period waves diminish
late week and winds nearshore become lighter and variable, these
long period westerly swells may pose a slight risk to beachgoers due
to increased wave run up. DB


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 5 PM PDT Wednesday for PZZ450-
     455-470-475.

&&

$$

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