056
FXUS66 KEKA 241044
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
344 AM PDT Mon Jun 24 2024

.SYNOPSIS...Interior warm and dry conditions continue through Tuesday
while marine stratus dampens coastal temperatures. An upper level
disturbance mid-week will allow for relatively cooler temperatures
through Thursday. Warming trend returns for this weekend into next
week.


&&

.DISCUSSION...Coastal stratus is slowly beginning to expand beyond the
Eel River Delta/Humboldt Bay area this morning beneath a shallow
marine inversion. HREF still has a strong signature indicative of
thickening stratus extending up to the Del Norte and Southern
Mendocino coasts after 6 am, although ceilings will likely be
limited to around 1000-1500 feet. Surface wind gust probabilities
significantly reduced today as the coastal pressure gradient
begins to diminish. HREF only indicating 15-25 mph gusts on
coastal headlands (Point Saint George, Cape Mendo and Pt Arena)
while lee coasts are slightly shielded.

Once again, coastal highs will remain dampened by marine stratus
redevelopment while hot temperatures are forecast for the interior.
NBM probabilities are favoring highs in the low to mid 90`s and
approaching/reaching 95-98 degrees again in the valleys of Southern
Mendocino, Lake and eastern Trinity counties - slightly reduced a
few degrees compared to this weekend. This pattern is expected to
remain largely consistent through Tuesday with daily surges in
diurnally driven NW flow.

Echoing the previous discussion, both GFS and NAM continue to
highlight a SE surge of mid-level subtropical moisture in 500-700
RH analysis beginning early Tuesday morning. NAM model soundings
show 100-300 J/KG MU Cape, aligning with weak signatures of hi-res
ARW simulated reflectivity in SE Mendocino and Lake counties by
early afternoon. Confidence is still quite low regarding the
potential for dry lightning, especially with weak lift and only
marginal instability, but this timeframe will be monitored closely
over the next 12-24 hours.

Otherwise, a pattern change is still expected early Wednesday into
Thursday as an upper level trough drops into the PNW, inducing
relative cooling of temperatures and slightly elevated westerly
winds. NBM probabilities drop off significantly in the upper 80`s
and low 90`s for the interior valleys, especially on Thursday
following a weak frontal passage. This bit of lift will likely be
sufficient to reduce coastal stratus in the latter half of the
week. 500 mb clusters are beginning to align in favor of
relatively zonal flow turning over to broad ridging late next
weekend for another warming trend.


&&

.AVIATION...IFR stratus has developed overnight in the Humboldt
Bay area and up the Eel River Delta early this morning, with wisps
drifting northward toward Del Norte at time of writing. Fog is
expected to mix out by mid-morning, with VFR expected this
afternoon for most of the coast. More expansive IFR ceilings will
most likely start to return late this evening, although
visibilities are expected to remain decent tonight. Otherwise,
widespread VFR conditions will persist for the interior with
normal summer conditions.


&&

.MARINE...Northerly winds persist this morning, then weaken this
afternoon, and by this evening only the southern waters are
forecasted to support short period seas steep enough for a small
craft advisory. Meanwhile a minor northwest swell of 5 feet at 11
seconds will persist through the day today then decay Tuesday.
Northerlies are forecast to remain below 15 kt for most zones during
Tuesday through Thursday morning, aside from the persistent 15-20 kt
northerlies expected directly downwind of Cape Mendo. Winds may
strengthen again Thursday afternoon into this weekend.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 PM PDT this afternoon for
     PZZ450-455-470.

     Small Craft Advisory until 9 AM PDT Tuesday for PZZ475.

&&

$$

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