039
FXUS66 KEKA 201349
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
549 AM PST FRI DEC 20 2024
SYNOPSIS
SOUTHERLY WINDS WILL INCREASE THROUGH THE DAY AHEAD STRONG
FRONTAL SYSTEM ARRIVING OVERNIGHT INTO SATURDAY. ADDITIONAL
ATMOSPHERIC RIVER STORMS ARE EXPECTED TO ARRIVE IN QUICK SUCCESSION
INTO NEXT WEEK.
DISCUSSION
HIGH CLOUD COVER WILL CONTINUE TO INCREASE TODAY AHEAD
OF A LOW PRESSURE SYSTEM. SCATTERED COASTAL AND INTERIOR VALLEY FOG
WAS STILL ABLE TO DEVELOP OVERNIGHT WITH LIGHT WINDS AND LOW LEVEL
MOISTURE. MILDER TEMPERATURES ARE EXPECTED AGAIN TODAY WITH HIGHS IN
THE UPPER 50'S AND LOW 60'S AS THE INITIAL WARM FRONTAL BOUNDARY
APPROACHES THE COAST. SOME LIGHT REFLECTIVITY RETURNS ARE ALREADY
APPEARING ON RADAR THIS MORNING, BUT ANY INITIAL RAINFALL IS
FORECAST TO BE LIGHT AND SHOWERY, WITH MOST NEAR TERM MODELS SHOWING
<0.10 INCHES, IF ANYTHING.
SOUTHERLY WINDS WILL INCREASE THROUGH THE DAY BEFORE A STRONG COLD
FRONT AND LL JET SLAM INTO THE NORTH COAST TONIGHT. MODEL GUIDANCE
CONTINUES TO SHOW A 55-65KT JET MAKING LANDFALL WITH THE AR
OVERNIGHT INTO EARLY SATURDAY. SURFACE WINDS ARE FORECAST TO
APPROACH 30 MPH ALONG COASTAL AREAS WITH ELEVATED TERRAIN REACHING
45 TO 55 MPH IN THE COAST RANGES, ESPECIALLY IN HUMBOLDT AND DEL
NORTE COUNTIES. A WIND ADVISORY IS IN EFFECT FOR THESE AREAS THROUGH
SATURDAY MORNING ESPECIALLY ALONG SOUTHERLY RIDGES AND EXPOSED
HEADLANDS.
RAINFALL TOTALS WILL LIKELY AMOUNT TO 0.50 TO 1.25 INCHES WITH
LOCALLY HIGHER AMOUNTS IN DEL NORTE AND AREAS IN THE KING RANGE
POTENTIALLY APPROACHING 2 INCHES. SOUTHEASTERLY FLOW WILL KEEP
RAINFALL ON THE LOWER END OF THESE TOTALS IN THE COASTAL PLAINS.
MODEL SOUNDINGS CONTINUE TO INDICATE THE POSSIBILITY FOR WEAK
CONVECTIVE SHOWERS OFFSHORE SATURDAY AFTERNOON; ISOLATED HEAVIER
DOWNPOURS ARE THEREFORE POSSIBLE ON THE COAST IN THE WAKE OF THIS
FRONT, ESPECIALLY NORTH OF THE CAPE.
THIS WILL MARK THE BEGINNING OF A SERIES OF ATMOSPHERIC RIVERS
IMPACTING THE PNW THIS WEEKEND INTO NEXT WEEK. MODEL GUIDANCE SHOWS
A SIMILARLY ORIENTED FRONT APPROACHING SUNDAY AFTERNOON, WITH
ADDITIONAL 0.5 TO 1.25 INCHES OF RAINFALL AND GUSTY SOUTHERLY WINDS.
NBM ONLY SHOWS AROUND 50% CHANCE OF GUSTS EXCEEDING 30 MPH, ALTHOUGH
THERE IS STILL A FAIR AMOUNT OF MODEL SPREAD. AFTER A BRIEF BREAK,
THE TRAINING SYSTEM ARRIVING MONDAY NIGHT INTO TUESDAY IS LOOKING
INCREASINGLY MORE IMPACTFUL WITH HEAVIER RAINFALL POSSIBLE. CURRENT
FORECAST FOR 2 TO NEARLY 4 INCHES IN PORTIONS OF INTERIOR DEL NORTE
AND IN THE KING RANGE, WITH THE HEAVIEST RAINFALL LIKELY OVERNIGHT
INTO TUESDAY. LONG RANGE MODELS SHOW HIGHER PROBABILITIES FOR WIND
GUSTS EXCEEDING 40 MPH WITH THIS FRONT. EACH SUCCESSIVE STORM WILL
ENABLE SWIFTER RESPONSE FROM RIVERS - CNRFC ENSEMBLES ARE SHOWING
SEVERAL RIVERS (INCLUDING THE EEL RIVER AT FERNBRIDGE, THE RUSSIAN
RIVER AT HOPLAND AND THE NAVARRO RIVER) HAVE 50% CHANCE OF REACHING
MINOR FLOOD STAGE BY WEDNESDAY. ADDITIONAL RAINFALL IS LOOKING MORE
LIKELY FOR THE LATTER HALF OF THE WEEK AS WELL, ALTHOUGH ORIENTATION
AND LATITUDINAL PLACEMENT OF THE AR COULD IMPACT THE FORECAST
SIGNIFICANTLY OVER THE NEXT SEVERAL DAYS.
AVIATION
THE ONSET OF A SERIES OF FRONTS BEGINS THIS
MORNING. ALTHOUGH NOT MUCH RAIN IS EXPECTED WITH THIS WARM FRONT,
GUSTY WINDS AT 2000 FEET WITH FRACTIONAL MIXING WILL GIVE WAY TO LOW
LEVEL WIND SHEER BY THE DAWN HOURS. VFR/MVFR ARE PERSISTING AT THE
COASTAL TERMINALS WITH SHORT PERIODS OF IFR. KUKI HAS HAD ANOTHER
NIGHT OF CONTINUOUS LIFR CATEGORIES, LASTING INTO THE MORNING.
EXPECT IMPROVEMENTS BY THE AFTERNOON WITH VFR CONDITIONS. LLWS IS
ALSO EXPECTED AT KUKI AROUND THE SUNSET HOURS AS ANOTHER FRONT
PASSES THROUGH. /EYS
MARINE
AS THE DAYLIGHT HOURS APPROACH, FAR OFFSHORE BUOYS ARE
BEGINNING TO INDICATE THE ARRIVAL OF A SERIES OF ANTICIPATED FRONTS.
THE TIMING FOR THIS FIRST SERIES IS A BIT LATER THAN INITIALLY
EXPECTED BUT IS LIKELY TO PRODUCE GALE FORCE GUSTS UP TO 40 KTS,
IN THE NORTHERN OUTER WATERS LATER THIS MORNING. THERE WILL BE A
BRIEF REPRIEVE BEFORE THE RETURN OF MORE WIDESPREAD GALE
CONDITIONS FOR THE NORTHERN AND SOUTHERN OUTER WATERS. GUSTS WILL
BE STRONGER LATER TONIGHT WITH GUSTS AROUND 50KTS IN THE OUTER
WATERS AND SOUTHERN INNER WATERS THROUGH SATURDAY EARLY MORNING.
THE FRONTAL SYSTEMS THAT ARE FORCING THE STRONG WINDS OVER THE
COASTAL WATERS ARE ALSO FORECASTED TO BRING MULTIPLE PULSES OF
LONG TO MID PERIOD SWELLS. THE FIRST OF THESE PULSES (18FT@15S) IS
FORECASTED TO ARRIVE THIS AFTERNOON, HOLDING STEADY THROUGH THE
WEEKEND. A FRONTAL SYSTEM PASSING IS FORECASTED TO SEND ANOTHER
PULSE (19- 22FT@19S) MONDAY EARLY MORNING AND A SHARP INCREASE IN
SOUTHERLY GALE FORCE WINDS. OFFSHORE LOW PRESSURE SYSTEMS TO THE
WEST ARE ROTATING THIS SERIES OF FRONTS INTO OUR AREA WATERS
THROUGH THE WEEKEND. EXPECT ANOTHER COLD FRONT SUNDAY WHICH THEN
DISSIPATES SUNDAY NIGHT WITH ANOTHER STRONG COLD FRONT MONDAY,
INTO TUESDAY.
HYDROLOGY
THE FIRST OF SEVERAL ATMOSPHERIC RIVERS IS FORECAST TO
ARRIVE OVERNIGHT INTO SATURDAY. RAINFALL TOTALS ARE LIKELY TO BE 0.5
TO 1.5 INCHES WITH THE HIGHEST TOTALS IN THE HIGHER TERRAIN OF
INTERIOR DEL NORTE AND HUMBOLDT. A STRONGER SYSTEM IS EXPECTED
MONDAY NIGHT INTO TUESDAY WITH MORE SIGNIFICANT RAIN IMPACTS. CNRFC
HAS A 50% CHANCE OF EXCEEDING MINOR FLOOD STAGE FOR THE EEL RIVER AT
FERNBRIDGE, THE RUSSIAN RIVER AND THE NAVARRO RIVER. AS MENTIONED IN
THE PREVIOUS DISCUSSION, FLOODING WILL DEPEND LARGELY ON HOW MUCH
THE RIVERS ARE ABLE TO DIMINISH IN THE BREAKS BETWEEN RAINFALL. THIS
WILL BE ESPECIALLY IMPORTANT FOR THE FOLLOWING SYSTEM ARRIVING
THURSDAY.
BEACH HAZARDS
A SERIES OF LONG PERIOD, WESTERLY SWELLS
WILL CONTINUE TO IMPACT THE COASTAL WATERS OF NORTHWEST CALIFORNIA
THROUGH NEXT WEEK. GFS WAVE MODEL SUGGEST THERE IS ANOTHER LARGE
SWELL AROUND 16 TO 18 FEET BUILDING ACROSS THE WATERS SATURDAY
MORNING AND WELL INTO SUNDAY MORNING. THIS IS EXPECTED TO BRING
BREAKERS BETWEEN 20 TO 22 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.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
BEACH HAZARDS STATEMENT UNTIL 3 PM PST THIS AFTERNOON FOR
CAZ101-103-104-109.
WIND ADVISORY FROM 6 PM THIS EVENING TO 10 AM PST SATURDAY
FOR CAZ102-104>106.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 PM PST
THIS EVENING FOR PZZ450.
GALE WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
PZZ450.
SMALL CRAFT ADVISORY UNTIL 11 PM PST THIS EVENING FOR
PZZ455.
GALE WARNING FROM 11 PM THIS EVENING TO 8 AM PST SATURDAY
FOR PZZ455.
GALE WARNING UNTIL 8 AM PST SATURDAY FOR PZZ470.
SMALL CRAFT ADVISORY UNTIL 6 PM PST THIS EVENING FOR PZZ475.
GALE WARNING FROM 6 PM THIS EVENING TO 8 AM PST SATURDAY
FOR PZZ475.
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