221
FXUS66 KEKA 251144
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
444 AM PDT Tue Jun 25 2024

.SYNOPSIS...Interior warm and dry conditions continue today while
marine stratus dampens coastal temperatures. Potential for high-
based storms today as mid-level moisture pushes into NorCal. An
upper level disturbance mid-week will allow for relatively cooler
temperatures through Thursday. Warming trend returns for this
weekend into next week.



&&

.DISCUSSION...Marine stratus once again enveloping the Humboldt coast.
Strong southerly wind reversal allowing the leading edge to migrate
north to the Oregon coast - a similar pattern is beginning to
appear along the southern Mendocino coast. HREF showing strong
signatures for <1000 ft ceilings continuing through tonight without
much reprieve, although the stratus shield may hover nearly flush
with the coastline this afternoon, allowing for some breaks before
pushing onshore again this evening. More significant reductions in
visibilities expected early Wednesday morning.

IR satellite and radar showing ongoing northeasterly progression of
convective showers from the central coast. Very light returns
beginning to reach southern Lake and coastal Mendocino counties as
of early this morning, but minimal lightning flashes remain well
offshore. CAMS guidance anticipating more substantial albeit
isolated returns developing around 15Z in Lake and Mendocino
counties. With NAM model guidance indicating wetter mid-level RH
values reaching further into Humboldt and Trinity counties this
afternoon, potential for scattered showers is certainly possible
further north. Main focus is still on Mendo and Lake counties,
especially as increasing temperatures induce instability this
afternoon. Lower levels are consistently dry, limiting development
but still posing a threat for gusty winds and potential for dry
lightning strikes.

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 again in
the valleys of Southern Mendocino, Lake and eastern Trinity
counties. Daily surges in diurnally driven NW flow may be
interrupted by isolated storm outflow.

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. This will be a concern for fire weather in the case of any
dry lightning starts - NW wind gusts 15-25 mph are possible
alongside RH`s <30% in Lake/S Mendocino counties. NBM temp
probabilities drop off significantly around 90 degrees for the
interior valleys on Wednesday, mid-80s on Thursday following a weak
frontal passage. Broad ridging looking more likely this weekend for
another warming trend before potential for another disturbance early
next week.




&&

.AVIATION...Expansive LIFR stratus has developed along the north
coast early this morning, while visibilities have remained VFR. This
low cloud is expected to retreat to the immediate coast by late
morning, but with lighter winds forecasted today it may linger just
offshore before moving back onshore this evening and tonight.
Otherwise, widespread VFR conditions will persist for the interior
with normal summer conditions.



&&

.MARINE...Northerly winds continue to weaken today, and are forecast
to significantly weaken tomorrow. Meanwhile a minor northwest swell
of 5 feet at 11 will slowly decay today. 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. Northerlies are expected
to strengthen again Thursday afternoon into this weekend.


&&

.FIRE WEATHER...Reflectivity returns beginning to cross into
Southern Mendocino and Lake counties this morning as mid-level
moisture pushes north into the region. Low potential for isolated
dry lightning amidst within elevated convection. Still, some of
these storms could produce gusty outflow winds. Increasing NW flow
on Wednesday combined with <25% RH values may pose a fire weather
risk in the case of any potential starts this afternoon. Greatest threat
to fuels in areas below 2000 feet.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM PDT early this morning for
     PZZ455.

     Small Craft Advisory until 9 AM PDT this morning for PZZ470-
     475.

&&

$$

Visit us at https://www.weather.gov/eureka

Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka

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