453
FXUS66 KEKA 202313
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
313 PM PST FRI DEC 20 2024
SYNOPSIS
SOUTHERLY WINDS WILL INCREASE THIS EVENING AHEAD OF
A STRONG, BUT QUICK MOVING FRONTAL SYSTEM ARRIVING OVERNIGHT INTO
SATURDAY MORNING. A FEW LINGERING SHOWERS ARE EXPECTED SATURDAY
AFTERNOON. THE NEXT SYSTEM IS EXPECTED SUNDAY AFTERNOON AND
EVENING WITH A WETTER SYSTEM MONDAY AFTERNOON. ADDITIONAL SYSTEMS
WILL CONTINUE MID TO LATE IN THE WEEK.
DISCUSSION
A WEAK WARM FRONT IS MOVING ONSHORE THIS MORNING.
THIS IS BRINGING CLOUDS TO THE AREA AND A FEW LIGHT SHOWERS TO DEL
NORTE COUNTY. WINDS HAVE STARTED TO INCREASE OVER THE HIGHER
TERRAIN WITH GUSTS TO 35 MPH SO FAR IN HUMBODLT AND DEL NORTE
COUNTIES. TONIGHT THESE WINDS WILL CONTINUE TO INCREASE AS A COLD
FRONT APPROACHES. THE 925 MB WINDS ARE SHOWING A MAX OF 65 KT JUST
OFF THE DEL NORTE COAST AT 12Z. THE SOUNDS ARE SHOWING SLIGHTLY
MORE UNSTABLE LOWER LEVELS ON THE DEL NORTE COAST AND THIS SHOULD
ALLOW GUSTS OF 45 TO 50 MPH TO MIX DOWN TO THE SURFACE FOR A FEW
HOURS. SO HAVE ISSUED A WIND ADVISORY FROM 2AM THROUGH 8AM. THE
WIND ADVISORY REMAINS OUT FOR THE HIGHER ELEVATIONS OF HUMBOLDT
AND DEL NORTE COUNTIES. THIS LOOKS ON TRACK. FARTHER EAST AND
SOUTH WINDS ARE EXPECTED TO BE LIGHT WITH GUSTS OF 30 TO 40 MPH.
THE RAIN TONIGHT IS EXPECTED TO BE MAINLY A BAND OF HEAVY RAIN
WITH THE FRONT LASTING SEVERAL HOURS. FORECAST RAINFALL AMOUNTS
HAVE DIMINISHED SLIGHTLY WITH MANY OF THE VALLEYS ONLY A HALF
INCH. THE MOUNTAINS MAY STILL SEE NEARLY TWO INCHES. THE WATER
VAPOR TRANSPORT IS FAIRLY HIGH FOR A FEW HOURS SO RAINFALL AMOUNTS
MAY BE HIGHER THAN EXPECTED. BEHIND THE MAIN FRONT THERE WILL BE
SOME SHOWERS. THERE IS THE POTENTIAL FOR A FEW THUNDERSTORMS, BUT
THE BEST CHANCES ARE JUST ALONG THE DEL NORTE COAST.
SATURDAY NIGHT INTO SUNDAY MORNING THERE IS EXPECTED TO BE A
BRIEF BREAK IN THE RAINFALL. THERE IS SOME UNCERTAINTY ON HOW LONG
THIS BREAK WILL BE. ON THE NORTH COAST IT MAY ONLY LAST THROUGH
MIDDAY SUNDAY WHILE AREAS FARTHER SOUTH AND EAST IT MAY REMAIN DRY
THROUGH MID AFTERNOON. THIS SYSTEM LOOKS TO HAVE SIMILAR RAINFALL
AMOUNTS TO THE EARLY SATURDAY MORNING SYSTEM, BUT WINDS LOOK
LIGHTER.
ANOTHER SHORT BREAK IS EXPECTED BEFORE MORE RAIN MOVES IN LATER ON
MONDAY. THIS SYSTEM IS EXPECTED BRING HEAVIER RAIN AND WIND.
RAINFALL AMOUNTS FROM MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON
LOOK TO BE AROUND 1 TO 3 INCHES WITH LOCAL AMOUNTS IN THE HIGHER
TERRAIN OF OVER 4 INCHES. IN MUCH OF THE HIGHER TERRAIN THE NBM IS
SHOWING 40 TO 70 PERCENT CHANCE OF MORE THAN 3 INCHES IN THE 24
HOURS. MOST OF THE AREA IS SHOWING AN 80 TO 100 PERCENT OF MORE
THAN AN INCH OF RAIN. THE IVT VALUES ON THE ENSEMBLE MEAN IS
NEARLY 500 KG/M/S FOR NEARLY 18 HOURS. IN ADDITION THIS AIRMASS
LOOKS REALLY WARM, SNOW LEVELS MAY BE OVER 8000 FEET FOR THE
HEAVIER RAIN. THIS IS THE SYSTEM THAT MAY START TO CAUSE
FLOODING. THIS SYSTEM IS EXPECTED TO COME TO AN END TUESDAY
AFTERNOON OR EVENING. FOR NOW IT LOOKS A PERIOD OF DRY WEATHER
TUESDAY NIGHT AND WEDNESDAY.
THURSDAY ANOTHER SYSTEM IS EXPECTED, THE MODELS ARE SHOWING A LOT
OF VARIABILITY IN THIS SYSTEM. THERE IS SOME ENSEMBLE AGREEMENT
THAT IT WILL BE A COLDER SYSTEM. THIS MAY BRING SNOW TO THE
HIGHWAY 299 CORRIDOR IN TRINITY COUNTY. NBM RAINFALL PROBABILITIES
ARE 75 TO 100 PERCENT FOR OVER AN INCH. PROBABILITIES OF OVER 4
INCHES ARE 40 TO 60 PERCENT OVER THE HIGHER TERRAIN. THIS HAS THE
POTENTIAL TO CAUSE FLOODING, MORE DETAILS IN THE HYDROLOGIC
SECTION. MKK
AVIATION
THE FORECAST AREA WILL BE HIT BY A QUICK MOVING WARM
FRONT LATE TONIGHT AND INTO TOMORROW EVENING. SHARP INCREASES IN
WIND WITH GUSTS UP TO 40KTS AT KCEC AND 30KTS AT KACV ARE
FORECASTED. WHEN THESE WINDS RAMP UP, RAINY CONDITIONS AND REDUCED
VISIBILITIES ARE TO BE EXPECTED IN TANDEM. MODEL SOUNDINGS
SUGGEST THAT CLOUD BASES WILL REMAIN ABOVE MVFR STATUS, SO IF
THERE IS A CATEGORY CHANGE, IT WOULD MOST LIKELY BE RELATED TO
PASSING SHOWERS. THE STORY IS DIFFERENT INLAND WHERE KUKI IS
REPORTING LIFR VALLEY FOG CONDITIONS, THIS FOG IS EXPECTED TO MIX
OUT BY NOON (20Z) TODAY. WIND SHEAR ALONG THE COAST IS EXPECTED
DUE TO THE MOVING FRONT OVERHEAD LEADING TO WINDS ONLY 1500-2000
FT AGL BEING UPWARDS OF 45- 55KTS ALONG THE COAST THIS EVENING
INTO TOMORROW MORNING.
MARINE
A PASSING WARM FRONT WILL SEND GALE FORCE WINDS THROUGH
THE COASTAL WATERS THIS AFTERNOON. THESE WINDS ARE FORECASTED TO
MOVE THROUGH THE AREA FROM NOW UNTIL AROUND SUNRISE TOMORROW MORNING
WITH THE PEAK WINDS OCCURRING AROUND MIDNIGHT TONIGHT. THESE WINDS
WILL CREATE STEEP, SHORT-PERIOD WIND WAVES LEADING TO HAZARDOUS
CONDITIONS IN ADDITION TO THE SOUTHERLY GALES. ANOTHER ROUND OF
STRONG TO NEAR-GALE-FORCE WINDS IS FORECASTED FOR SUNDAY.
THE CURRENT W SWELL SEEMS TO BE HOLDING STEADY AT AROUND 8FT@14S
THROUGH THIS MORNING. THROUGH THE NIGHT, THIS SWELL WILL BUILD,
PEAKING AT 20FT@16S CREATING HAZARDOUS SEAS DUE TO ABNORMALLY LARGE
WAVES ON SATURDAY AFTERNOON - SUNDAY MORNING. MONDAY CURRENT SHOWS A
LARGER NW SWELL OF 23FT@20S. MORE DETAILS ON THE SPECIFICS OF THESE
INCOMING WAVE GROUPS WILL BE AVAILABLE EITHER TONIGHT OR TOMORROW AS
MORE WAVE/WIND MODELS INITIALIZE AS THE STORMS CAUSING THEM EVOLVE
THROUGHOUT THE DAY.
BEACH HAZARDS
A SERIES OF LONG PERIOD, WESTERLY SWELLS WILL
CONTINUE TO IMPACT THE COASTAL WATERS OF NORTHWEST CALIFORNIA
DURING NEXT WEEK. THE CURRENT SWELL HAS BEEN SUBSIDING THROUGH THE
DAY. HOWEVER, A HIGH SURF ADVISORY COULD BE ISSUED AFTER THE
BEACH HAZARD STATEMENT EXPIRES TO MINIMIZE CONFUSION ON THE
TIMING OF THESE EVENTS. THIS SECOND HAZARD IS EXPECTED DUE TO THE
GFS WAVE MODEL SUGGESTING ANOTHER LARGE SWELL OF AROUND 18 TO 20
FEET BUILDING ACROSS THE WATERS SATURDAY MORNING UNTIL SUNDAY
MORNING. THIS IS EXPECTED TO BRING BREAKERS BETWEEN 21 TO 23 FEET
ALL DAY SATURDAY INTO THE EARLY HOURS OF SUNDAY. HAZARDOUS SURF
CONDITIONS DUE TO THE BREAKING WAVES WILL BE POSSIBLE ALONG WEST-
NORTHWEST FACING BEACHES. MORE HAZARDOUS SURF IS FORECASTED FOR
DECEMBER 23RD AND MORE DETAILS ABOUT THIS 2ND EVENT WILL BE
AVAILABLE IN THE COMING DAYS.
HYDROLOGY
THE FIRST IN A SERIES OF ATMOSPHERIC RIVERS IS
EXPECTED TO HIT TONIGHT. LOCALLY HEAVY RAINFALL RATES ARE EXPECTED
AND THERE MAY BE SOME MINOR STREET FLOODING. THE NEXT SYSTEM
SUNDAY AFTERNOON IS EXPECTED TO BE SIMILAR. THE EXACT RAINFALL
AMOUNTS AND BREAKS BETWEEN SYSTEMS WILL BE KEY FOR THE NEXT SYSTEM
MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON. THIS ONE MAY BRING
SOME FLOODING OF SMALL STREAMS. IN ADDITION THERE IS THE POTENTIAL
FOR SOME RIVER FLOODING GIVEN THE RAIN LEADING UP TO THIS EVENT.
RAINFALL IS EXPECTED TO LAST CLOSER TO 18 HOURS WITH THIS THIRD
SYSTEM. THE MAD, EEL, RUSSIAN AND NAVARRO RIVERS ARE EXPECTED TO
RISE SIGNIFICANTLY AND MANY OF THEM ARE GETTING CLOSE TO
MONITOR/ACTION STAGE. THESE WILL NEED TO BE WATCHED AS IT GETS
CLOSER. MKK
EKA WATCHES/WARNINGS/ADVISORIES
CA...
WIND ADVISORY FROM 2 AM TO 8 AM PST SATURDAY FOR CAZ101.
HIGH SURF ADVISORY FROM 3 PM SATURDAY TO 9 AM PST SUNDAY
FOR CAZ101-103-104-109.
WIND ADVISORY UNTIL 10 AM PST SATURDAY FOR CAZ102-104>106.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 11 PM PST THIS EVENING FOR
PZZ450-455.
GALE WARNING FROM 11 PM THIS EVENING TO 8 AM PST SATURDAY
FOR PZZ450-455.
GALE WARNING UNTIL 8 AM PST SATURDAY FOR PZZ470.
SMALL CRAFT ADVISORY UNTIL 6 PM PST THIS EVENING FOR PZZ475.
GALE WARNING UNTIL 8 AM PST SATURDAY FOR PZZ475.
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