762
FXUS66 KEKA 071201
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
501 AM PDT TUE JUL 7 2020
SYNOPSIS
NEAR NORMAL TEMPERATURES ARE EXPECTED IN THE INTERIOR
THROUGH THE WEEK. MARINE AIR AND ONSHORE BREEZES WILL KEEP COASTAL
AREAS SEASONABLY COOL.
DISCUSSION
HIGH PRESSURE WILL BUILD TOWARD THE COAST TODAY IN THE
WAKE OF A SHORTWAVE TROUGH THAT PRODUCED A DEEP MARINE LAYER AND
A SHARP DROP IN HIGH TEMPERATURES ACROSS THE INTERIOR YESTERDAY.
BRISK AND GUSTY NORTH-NORTHWESTERLY WINDS ARE EXPECTED FOR THE
COASTAL AREAS LATER TODAY AND AGAIN ON WEDNESDAY. CLOUD COVER
WILL ALSO BE LESS. BREEZY WESTERLY TO NORTHWESTERLY CONDITIONS
ARE ALSO EXPECTED IN THE INTERIOR, HOWEVER RELATIVE HUMIDITIES
HAVE BEEN TRENDING UPWARD OVERNIGHT AT MANY REPORTING STATIONS IN
THE INTERIOR.
A BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE AREA THROUGH MID
WEEK. TEMPERATURES IN THE INTERIOR WILL GENERALLY EDGE UPWARD
THROUGH THE WEEK AS THE TROUGH SLOWLY LIFTS NORTHWARD. ONSHORE
BREEZES WILL LIKELY KEEP MOST INTERIOR TEMPERATURES NEAR OR
SLIGHTLY ABOVE NORMAL. A STRONG UPPER RIDGE CENTERED OVER THE
FOUR CORNERS REGION WILL EXPAND SLIGHTLY WESTWARD LATE IN THE
WEEK. ANOTHER TRANSIENT TROUGH WILL PROBABLY KNOCK THE RIDGE DOWN
OVER THE WEEKEND AND TEMPERATURES SHOULD NOT WARM TO EXTREME
LEVELS, 105-110F, IN THE INTERIOR. ENSEMBLE GUIDANCE, NAMELY THE
GEFS PLUMES, INDICATE LARGER SPREADS IN 850MB TEMPERATURES NEXT
WEEK. EPS AND CMCE MEANS WERE SLIGHTLY WARMER COMPARED TO THE GEFS
MEAN.
AVIATION
OVERNIGHT, THE MARINE LAYER CONTINUED TO DEEPEN IN
RESPONSE TO UPPER-LEVEL TROUGHING PASSING BY. OBSERVATIONS AND
PROFILE IMAGERY REVEALED THE LAYER REACHED OVER 3,500 FEET IN DEPTH.
THROUGH THE EARLY MORNING HOURS, THE COASTAL TERMINAL HELD VFR
CONDITIONS WHILE STRATUS LOOMED IN THE VICINITIES OF KCEC AND KACV.
VFR GAVE WAY TO PERIODS OF LIFR CEILINGS AS THE STRATUS FILLED BACK
IN. HIGH PRESSURE RIDGING WILL BEGIN BUILDING IN TODAY, ACTING TO
COMPRESS THE MARINE LAYER SOMEWHAT. IMPROVEMENT IS EXPECTED TOMORROW
DURING TYPICAL DIURNAL TRENDS; HOWEVER, THE LAYER WILL STILL BE DEEP
ENOUGH TO POTENTIALLY DELAY THIS. THE MARINE LAYER WILL REMAIN
THREATENING CLOSE TO SHORE TODAY, POTENTIALLY BREACHING THE COAST AT
TIMES BEFORE EVENTUAL COMPLETE RESURGENCE INTO THE EVENING.
/JJW
MARINE
THE WATERS HAVE HELD A PERSISTENT PATTERN OF A MODERATE
NORTHERLY WIND REGIME, FOCUSED ON THE LEE SIDE OF CAPE MENDOCINO.
WITH THE PASSING OF AN UPPER-TROUGH, THE PATTERN WILL SHIFT WITH A
TEMPORARY RIDGE BUILDING IN BEHIND IT. IN RESPONSE, THE PRESSURE
GRADIENT WILL TIGHTEN UP AND ALLOW THE STRONGER WINDS TO EXPAND INTO
THE NORTHERN OUTER WATERS BEGINNING THIS AFTERNOON, AND REACHING
SMALL CRAFT ADVISORY LEVELS INTO THE EVENING. AS IS TYPICAL ON THE
LEE SIDE OF CAPE MENDOCINO, WINDS WILL ACCELERATE WITH SOME LOCAL
GUSTS APPROACHING GALE FORCE POSSIBLE IN THE AFTERNOONS AND EVENINGS
THROUGH WEDNESDAY. STEEP SEAS WILL GENERALLY BUILD TO 7 FEET IN THE
OUTER WATERS, WITH 8 TO 9 FEET IN ISOLATED AREAS SOUTH OF THE CAPE.
THE NORTHERLY WIND REGIME WILL PERSIST LATER INTO THE WEEK. HOWEVER,
WITH ANOTHER TROUGH OF LOW PRESSURE PASSING BY TO OUR NORTH, THE
PRESSURE GRADIENT AND CORRESPONDING NORTHERLY WINDS WILL EASE BACK
AGAIN TO THE NORTH OF CAPE MENDOCINO. THIS SHOULD ALLOW FOR LOWER
SEAS ACROSS OUR WATERS AS WELL, BUT CONDITIONS WILL REMAIN LOCALLY
ROUGH TO THE LEE OF CAPE MENDOCINO. JJW/AAD
EKA WATCHES/WARNINGS/ADVISORIES
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 3 AM PDT
THURSDAY FOR PZZ470. SMALL CRAFT ADVISORY UNTIL 9 PM PDT
WEDNESDAY FOR PZZ455. SMALL CRAFT ADVISORY UNTIL 3 AM PDT
THURSDAY FOR PZZ475.
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