FXUS66 KEKA 302221
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
321 PM PDT Tue Jul 30 2024

.SYNOPSIS...Hot weather with moderate heat risk will return in
the interior on Wednesday and persist for the next 7 days.
There is a slight chance of thunderstorms in northern Trinity
county Friday evening and Saturday.

&&

.DISCUSSION...500mb ridge will build tonight into Wed and smash
down the marine layer. Deep humid layer this morning will decrease
tonight with stratus and fog confined to coastal areas and
adjacent river valleys. Stratus and fog has been locked onto the
Mendocino coast for multiple days now and with a strong marine
inversion building tonight and Wed, confidence stratus will clear
is not high. With 500mb heights increasing to 590DM and 850mb of
22-30C, interior valley temperatures of 95-102F are highly
probable (80% chance) on Wed. Moderate heat risk is forecast to
continue for the remainder of the week with high temperatures for
the inland valleys in the upper 90s to 104F. Greater uncertainty
with additional warming and higher heat risk arises for the weekend
as mid level humidity and high based mid level clouds increase.
PWATs will increase over 1 inch, however soundings indicate water
vapor above 10,000-15,000 feet. With a strong mid level cap and
convective inhibition apparent on model soundings, not confident
the mid layer moisture will necessarily result in thunderstorms
even with daytime heating and terrain forcing. A few light showers
or sprinkles will certainly be possible. Dry lightning is possible,
however right now confidence on the details and timing remains low.
NBM thunderstorm probabilities increase to 15-20% over NE Trinity
on Saturday, while SPC has a broad area of a 10% chance from 12Z
Sat-12 Sun. Stay tuned.

Ensemble means and clusters indicate a strengthening 500mb ridge
early to mid next week. NBM probabilities for max temperatures of
105F or more increase to 50% or more, while probabilities for 110F
increase to 10-20%. Heat risk may increase to major level or extreme
early to mid next week if overnight lows remain elevated; in the
mid 80s to lower 90s.

DB

&&

.AVIATION...Ceilings have lifted at the coastal terminals this
afternoon to around 1500 feet. Flight categories have been LIFR
through the morning but are now transitioning to VFR at KCEC and
MVFR at KACV as cloud groups are scattering out. Marine stratus is
abundant offshore and with HREF suggesting a return to less than
1000 feet by midnight, a return to LIFR at the coastal terminals is
likely before midnight. Sustained wind speeds are forecast to be
light and variable after midnight as well. KUKI is the only terminal
that HREF signals above 10 mph during the reoccurring late afternoon
gusts. Otherwise VFR expected to prevail at KUKI. EYS

&&

.MARINE...Seas are reporting around 3 feet amidst light winds.
Elevated 15 to 20 kt gusts are expected nearshore and downwind of
Cape Mendocino late tonight into early Wednesday as an upper trough
finally exits the region and a warm ridge begins to build. Interior
temperatures are expected to gradually increase through late week,
strengthening the coastal pressure gradient and enhancing coastal
winds by early this weekend. EYS

&&

.FIRE WEATHER...Warming and drying trend is on track in the
interior for the remainder of this week. Not much change expected
over the weekend with min RH's of 10-20% for Trinity, Lake and
interior Mendocino zones. Poor overnight recovery with RH <30% for
some of the exposed ridges and areas within the thermal belt is
also anticipated. Looking at NBM 90th percentile peak gusts, winds
are forecast to be diurnally driven with upslope and upvalley
winds every day this week in the interior. Granted coastal
mountains will be more exposed to N-NW breezes and peak gusts to
35 mph are possible. With low min RH's (<20%) expected late this
week and over the weekend, brief/locally critical conditions are
possible with afternoon gusts to 20-25 mph. There is also a chance
for isolated thunderstorms late Friday into this weekend, however
confidence on the timing or even if storms occur in or around our
forecast area remains low. DB

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
None.
&&

$$

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