855
FXUS66 KEKA 072208
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
308 PM PDT Sun Jul 7 2024

.SYNOPSIS...Extreme heat has only slightly started to back off
today. A cooling trend will continue to build through the week
thought temperatures will remain solidly above normal.


&&

.DISCUSSION...Extreme heat has eased only slightly today with most
inland locations trailing just a few degrees coolers. Ukiah for
example is still on track to hit around 112 with 110 around Willow
Creek. Though not all time records, such numbers are still likely to
beat daily records. The coast, however, is substantially cooler int
he 60s thanks to weakening high pressure and strengthening onshore
flow. Such a trend is, thankfully, a sign of things to come.

High pressure will slowly continue to ease through early this week.
The coast will see the strongest temperature decrease as the
subsidence inversion begins to lift and a proper marine layer begins
to form by Monday. This will bring coastal highs back into the 60s
and near coastal Valleys, such as Eel River Valley, back below 100.
Inland areas are not so lucky. Though temperatures will most likely
cool about 10 degrees by Tuesday, that still puts interior highs
around 100 with lows in the 60s. Though certainly an improvement,
such temperatures will most likely maintain at least moderate to
major HeatRisk through the week.

Later in the week, even as heat persists, model ensembles show good
agreement of southerly wind building aloft under the influence of an
upper level shortwave. Such a pattern can be conducive to
thunderstorms development, that said most models remain very dry
with very weak moisture plume aloft. As such, none of the
thunderstorm probabilities are showing anything more than 5 percent
until late in the week. Even then they only peak around 8 to 10
percent in Trinity county. These thunderstorms would likely be
fairly dry if they do occur. /JHW


&&

.AVIATION...VFR conditions and mild winds across all terminals
again this afternoon. Flow will remain west/northwest through the
early evening at the coast, while strong diurnal heating will likely
channel gusty northerly winds down into UKI this afternoon in the
few hours before sunset. Winds are expected to quickly diminish by
late evening and turn southerly after midnight at all terminals.
HREF is indicating stronger probabilities for IFR stratus ceilings
and reduced visbilities to settle into the coast north of Cape
Mendocino early Monday morning, especially around Humboldt Bay.
Model soundings are in agreement on strong mid level subsidence
allowing a shallow marine layer to develop and saturate. Conditions
appear more favorable than this morning for a southerly reversal to
advect this stratus north to CEC, although probabilities are still
greater at ACV.


&&

.MARINE...Northerly winds and waves expected to continue increasing to
advisory levels in the outer waters downwind of Port Orford and Cape
Mendocino, with stronger gusts 25-30 knots possible within the inner
waters lee of the Cape. Square 6-7 foot wave response expected
through Monday as the ridge generates a stronger coastal pressure
gradient. Seas are trending slightly lighter in the northern waters,
advisory will expire Monday afternoon while the southern waters will
maintain wave response through Tuesday morning. Conditions will only
diminish slightly mid-week before northerly winds begin to
accelerate in the outer waters again Wednesday into Thursday. Long
range models are beginning to suggest gales in the outer waters by
late this week with potential for steep and hazardous seas, although
this will subject to change over the next few days as confidence
varies.


&&

.FIRE WEATHER...Prolonged and extreme heat and dryness have
continued to enhance fire weather conditions all across the area.
Low pressure setting up along the coast has locally enhanced terrain
winds, mostly along the Trinity River Valley. Though gentle in
absolute terms (gusts below 20 mph) combined with extremely dry RH,
at least brief critical fire weather conditions this evening.

Fire danger will ease slightly this week as temperature decreases
and RH eeks back closer to 20% with increased marine influence.
Still, RH temperature will remain solidly above average with dry
conditions through the week. Winds will remain predominately terrain
driven and onshore early this week, though a growing southerly delta
breeze in the Sacramento Valley will likely clip Lake COunty each
afternoon, brining some stronger gusts though also increasing RH.

As mentioned in the main discussion above, model ensembles are
consistently showing a pattern mid to late week that could generate
isolated thunderstorms. A very dry profile generally has thunder
chances below 10 percent, but any storms that do form will be dry.
Uncertainty remains high, but given the recent fuel dryness, any
lightning could be impactful. /JHW


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Heat Advisory until 8 PM PDT Monday for CAZ102-112.

     Heat Advisory until 11 PM PDT this evening for CAZ104-106.

     Excessive Heat Warning until 8 PM PDT Monday for CAZ105-107-
     108-110-111-113>115.

     Red Flag Warning until 11 PM PDT this evening for CAZ283.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 PM PDT Monday for PZZ470.

     Small Craft Advisory until noon PDT Tuesday for PZZ475.

&&

$$

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