491
FXUS66 KEKA 241156
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
456 AM PDT THU APR 24 2025
SYNOPSIS
AN UPPER LEVEL TROUGH APPROACHING THE AREA WILL BRING
COOLER TEMPERATURES ACROSS THE INTERIOR THROUGH SATURDAY.
THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS OVER THE MOUNTAINS FOR
THE NEXT FEW DAYS AS WELL AS WIDESPREAD SHOWERS IN MOST AREAS BY
FRIDAY. COOL NIGHTS AND PLEASANT SUNNY AFTERNOONS WILL RETURN SUNDAY
AND INTO NEXT WEEK.
DISCUSSION
THE APPROACH OF A DEEP UPPER LEVEL TROUGH IS EVIDENT
AS HIGH LEVEL CLOUDS ENCROACH ON THE CWA. THE TROUGH AXIS IS
CURRENTLY AT THE -140W LONGITUDE WITH A TRAJECTORY THAT WILL PLACE
THE VORTICITY MAX SOMEWHERE SOUTH OF THE SF BAY AREA. THIS OPEN WAVE
PATTERN TROUGH WILL DEEPEN AND FORM A SPLIT FLOW LOW BY FRIDAY
AFTERNOON, WITH THE LEADING EDGE BRINGING SOUTHERLY WINDS AND
INSTABILITY AS COLD AIR ADVECTS/OVERRUNS THE WARM AIR MASS. LEANING
MORE TOWARDS A POSITIVE TILT WITH THIS SYSTEM, THERE WILL BE LESS
CHANCE OF A SEVERE STORM OUTBREAK YET LOCALIZED CONVECTION IS
EXPECTED FOR THE INTERIOR MOUNTAINS. PWAT VALUES INCREASE BY THE
WEEKEND TO AROUND 0.8 INCHES.
THIS AFTERNOON INLAND AREAS ARE EXPECTED TO SEE A NUMBER OF SHOWERS
AND POSSIBLY SOME THUNDERSTORMS AS WELL. CAPE VARIES QUITE A BIT OF
MODEL TO MODEL, BUT THE HREF MEAN IS SHOWING AROUND 200 J/KG.
SHEAR IS ONLY AROUND 20 KT AND MID LEVEL LAPSE RATES ARE GENERALLY
AROUND 6.5 TO 7C/KM. THIS WILL LIKELY BE ENOUGH TO GENERATE A FEW
THUNDERSTORMS THIS AFTERNOON AND WELL INTO THE EVENING.
TONIGHT INTO FRIDAY, SHOWERS ARE EXPECTED TO BECOME MORE WIDESPREAD
AS THE UPPER LEVEL TROUGH MOVES IN. THERE IS THE POTENTIAL FOR SOME
THUNDERSTORMS AGAIN FRIDAY AFTERNOON. SATURDAY THE UPPER LEVEL LOW
STARTS TO MOVE OUT OF THE AREA, BUT THERE IS EXPECTED TO BE A
RESURGENCE OF SHOWERS IN THE AFTERNOON WITH THE DAYTIME HEATING.
HIGH TEMPERATURES ACROSS THE AREA EXPECTED TO STRUGGLE TO BREAK 60
DEGREES EVEN IN THE WARMER AREAS. OVERNIGHT LOWS ARE NOT EXPECTED TO
DROP TOO MUCH DUE TO THE MOISTURE AND CLOUDS AROUND. ANY AREAS THAT
DO REMAIN CLEAR SATURDAY NIGHT COULD SEE SOME FROST.
SUNDAY CLEARING SKIES ARE EXPECTED AND TEMPERATURES WILL START TO
WARM BACK UP AGAIN. INLAND AREAS ARE EXPECTED TO SEE HIGHS IN THE
60S. SUNDAY NIGHT INTO MONDAY MORNING IS EXPECTED TO BE THE COLDEST
NIGHT AND FROST IS POSSIBLE IN THE COLDER VALLEYS. HIGH PRESSURE
CONTINUES TO BUILD IN THROUGH THE WEEK WITH HIGHS AROUND 80 FOR THE
INLAND AREAS BY WEDNESDAY. /MKK /EYS
AVIATION
HIGH LEVEL CLOUDS ARE FORECAST TO COVER THE CWA AS A LOW
PRESSURE SYSTEM ADVANCES. MVFR FLIGHT CONDITIONS ARE EXPECTED
THROUGH THE TAF PERIOD AS CEILINGS DROP TO AROUND 1500-2000FT. BOTH
KCEC AND KACV WILL PROBABLY SEE LIGHT RAIN TONIGHT. KACV HAS ALREADY
RECEIVED LIGHT RAIN AS OF 11Z AS VERTICALLY INTEGRATED MOISTURE
CONDENSES. COASTAL STRATUS IS PREVALENT THIS MORNING BUT CONFIDENCE
IS LOW FOR THIS TO EFFECT CONDITIONS AT KUKI.
MARINE
SEAS ARE DROPPING EARLY THIS MORNING BUT REMAINING STEEP
WAVES KEEP ADVISORY LEVELS INTO MIDDAY THURSDAY. THERE IS A
PRONOUNCED AND PERSISTENT WIND EDDY FOR THE FAR NORTHERN INNER ZONE
AND AROUND POINT ST GEORGE STARTING TONIGHT AROUND 8 PM. THE
RESULTING LOCALIZED SOUTHERLY FLOW WILL GENERATE SOUTHERLY WINDS
THROUGH MOST OF THURSDAY.
A WEAK COLD FRONTAL SYSTEM WILL MOVE INTO THE AREA THURSDAY AND
WEAKEN THE PRESSURE GRADIENT. AS A RESULT, WINDS THURSDAY AFTERNOON
WILL BE LIGHTER THAN YESTERDAY, WITH EVEN LOWER WINDS AND SEAS OF 5
FT ON FRIDAY. IN THE WAKE OF THE FRONTAL SYSTEM, NORTHERLY WINDS
WILL BEGIN TO INCREASING FRIDAY NIGHT THROUGH SATURDAY. WINDS OF UP
TO 25 KTS ARE FORECAST SATURDAY EVENING, AND CAN BE EXPECTED TO
PERSIST INTO NEXT WEEK. THERE IS CURRENTLY A LOW PROBABILITY FOR
GALE FORCE GUSTS OVER 34 KTS (25-35%) THROUGH THAT PERIOD, AND
MAINLY FOR THE AFTERNOONS SOUTH OF CAPE MENDOCINO AND POINT ST.
GEORGE.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 5 AM PDT EARLY THIS MORNING FOR
PZZ450-455.
SMALL CRAFT ADVISORY UNTIL 11 AM PDT THIS MORNING FOR
PZZ470-475.
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