626
FXUS66 KEKA 160936
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
136 AM PST TUE DEC 16 2025
SYNOPSIS
LIGHT TO MODERATE AND LOCALLY HEAVY RAIN IS FORECAST
TO CONTINUE THROUGH TONIGHT FOR MOSTLY DEL NORTE, HUMBOLDT,
TRINITY AND NORTHERN MENDOCINO COUNTIES. A BREAK IN THE RAIN IS
FORECAST ON WEDNESDAY, FOLLOWED ANOTHER HIGH CHANCE FOR HEAVY RAIN
EITHER ON THURSDAY OR FRIDAY. ANOTHER CHANCE FOR HEAVY RAIN AND
STRONG WINDS WILL ARRIVE FOR THE LATTER PORTION OF THE WEEKEND.
DISCUSSION
A QUASI-STATIONARY FRONTAL SYSTEM HAS DEVELOPED
OVER THE NORTHERN PORTION OF NORTHWEST CALIFORNIA OVERNIGHT.
SATELLITE AND RADAR IMAGERY DEPICTS A SECONDARY PULSE OF MOISTURE
EXTENDING WESTWARD AND QUICKLY APPROACHING THE AREA. LIGHT TO
MODERATE RAIN CONTINUES MOVING ONSHORE FROM WEST- SOUTHWEST ACROSS
THE SOUTHERN HALF PORTION OF HUMBOLDT, SOUTHERN TRINITY AND FAR
NORTHERN MENDOCINO COUNTIES. THESE SHOWERS ARE EXPECTED TO INCREASE
IN COVERAGE AND EVENTUALLY BECOME MORE WIDESPREAD STRATIFORM RAIN
THIS MORNING WITH THE WAA AND MOISTURE PLUME SHIFTING SOUTHWARD.
LOCALIZE HEAVY RAINFALL (RAIN RATES > 0.25 IN/HR) IS EXPECTED OVER
THE SOUTHWEST WINDWARD-FACING TERRAIN IN DEL NORTE, HUMBOLDT AND
SOUTHWEST TRINITY COUNTIES. DEEPER MOISTURE IS EXPECTED TO ARRIVE
THIS EVENING, ENHANCING THE POTENTIAL OF HEAVIER RAINFALL AMOUNTS.
THIS WILL NEED TO BE WATCHED FOR POSSIBLE URBAN AND SMALL STREAM
FLOODING AND POSSIBLE ROCK/MUD SLIDES. ADDITIONAL RAINFALL OF 1 TO
2 INCHES IS EXPECTED ACROSS MUCH OF THE FORECAST AREA FROM 11 PM
MONDAY TO 4 AM WEDNESDAY, WITH LOCALLY UP TO AROUND 3.5 INCHES
OVER THE WINDWARD- FACING TERRAIN IN DEL NORTE AND HUMBOLDT
COUNTIES. MUCH LIGHTER RAIN RATES ARE EXPECTED FOR SOUTHERN
MENDOCINO AND LAKE COUNTIES WITH STORM TOTAL RAIN AROUND 0.10 TO
0.50 INCHES ENDING 4 AM WEDNESDAY.
BREEZY TO GUSTY SOUTHWEST WINDS ARE EXPECTED DEVELOP THIS
AFTERNOON ALONG THE NORTH COAST. PEAK WIND GUSTS AT LOWER
ELEVATIONS WILL MOST LIKELY BE 20 TO 35 MPH, WITH LOCALLY UP TO 40
MPH OVER THE MORE PROMINENT TERRAIN IN DEL NORTE COUNTY. WINDS
GUSTS WILL MOST LIKELY BE STRONGEST THIS EVENING AND TONIGHT WITH
THE HEAVIER RAIN. HREF MEAN SUGGEST WIND GUSTS INCREASING TO
AROUND 30 TO 40 MPH IN THE LOWER ELEVATION FROM 10PM TO 3AM, WITH
50-75% CHANCE OF IMPACTFUL GUSTS OVER 45 MPH ON HIGH COASTAL
RIDGES. ECMWF ENSEMBLE INDICATES POTENTIAL FOR STRONGEST WINDS
THURSDAY OR THURSDAY NIGHT, THOUGH THERE CONTINUES TO BE LARGE
SPREADS. ABOVE AVERAGE WARMTH AND FAIRLY HIGH SNOW LEVELS WILL
SEVERELY LIMIT ALL PROSPECTS FOR SIGNIFICANT SNOWFALL EXCEPT OVER
THE HIGHEST MOUNTAIN PEAKS.
THERE REMAINS GENERALLY HIGH CONFIDENCE (80% CHANCE) THAT A
WET PATTERN WILL CONTINUE THROUGH THE END OF THE WEEK AND INTO
THE WEEKEND. GFS AND ECMWF CONTINUES TO DEPICT ANOTHER MOIST PLUME
IMPACTING THE NORTHERN MOST PORTION OF THE AREA ON THURSDAY.
EVENTUALLY THIS BOUNDARY MOVES ACROSS THE AREA BY FRIDAY, THOUGH
IT COULD SPEED UP OR SLOW DOWN. HIGH PRESSURE AND GENERALLY DRIER
CONDITIONS ARE EXPECTED FOR SATURDAY, HOWEVER ANOTHER STORM IN THE
LINE UP WILL BEGIN TO SPIN UP OFFSHORE AND MAY BEGIN TO IMPACT
THE AREA AS EARLY AS SAT NIGHT OR SUN. THIS LOW PRESSURE SYSTEM HAS
THE POTENTIAL TO GENERATE STRONG AND DAMAGING WINDS AS WELL AS MORE
HEAVY RAIN. TIMING IS STILL UNCERTAIN. LOOKING AT THE CHANCE OF IVT
> 250 KG/M/S THE FOLLOWING WEEK DEC 22-26, CONFIDENCE IS MODERATE TO
HIGH IN WET WEATHER CONTINUING FOR LATTER PORTION OF DEC. CPC'S 8-14
DAY OUTLOOK ALSO HAS NW CA IN A HIGH RISK FOR HEAVY PRECIP AND A
MODERATE RISK FOR HIGH WINDS. STAY TUNED. /ZVS & DUG
AVIATION...06Z TAFS
SCATTERED SHOWERS HAVE GENERALLY GENERATED
IFR TO LIFR CEILINGS AND VISIBILITIES ACROSS THE AREA OVERNIGHT.
SLIGHT IMPROVEMENT IS EXPECTED AROUND HUMBOLDT BAY THIS MORNING AS
NOW SLOPING WIND HELPS LIFTS CEILINGS, BUT OTHERWISE SIMILAR
CONDITIONS WILL PERSIST THROUGH THE MORNING. ANOTHER ROUND OF
STRONGER SHOWERS WILL MOVE IN EARLY TUESDAY AFTERNOON, WIPING OUT
ANY IMPROVEMENT AND CREATING GENERALLY INCONSISTENT IFR CONDITIONS
FOR THE THE NORTHERN HALF OF THE AREA. WEAKER RAIN AND MID LEVEL
CEILINGS WILL LIKELY PROMOTE MVFR CONDITIONS FOR THE SOUTHERN HALF
OF THE AREA. ENSEMBLES GENERALLY SUGGEST SLIGHT IMPROVED CONDITIONS
BEHIND THE SYSTEM INTO EARLY WEDNESDAY. /JHW
MARINE
MODERATE SOUTHERLY WINDS WILL GENERALLY WEAKEN FOR
MUCH OF TUESDAY, BUT A MID PERIOD WESTERLY SWELL BUILDING OVER 10
FEET WILL MAINTAIN MODERATELY STEEP SEAS AT LEAST FOR THE THE
NORTHERN WATERS THROUGH MOST OF THE DAY. ANOTHER STORM SYSTEM WILL
CROSS THE AREA LATE TUESDAY INTO EARLY WEDNESDAY. SOUTHERLY WINDS
WILL AGAIN ONLY BRIEFLY INCREASE OVER 20 KTS AND WILL BE MOSTLY
RESTRICTED TO THE NORTHERN WATERS.
CALMER CONDITIONS WILL ARRIVE AGAIN WEDNESDAY AFTERNOON THOUGH, ONCE
AGAIN, A MID PERIOD WESTERLY SWELL UP TO 10 FEET WILL LIKELY
MAINTAIN VERY MODERATELY STEEP SEA IN THE NORTHERN WATERS. A
STRONGER STORM SYSTEM IS EXPECTED AROUND FRIDAY. THIS STORM WILL
SPREAD STRONGER SOUTH WINDS MORE INTO THE SOUTHERN WATERS WITH NEAR
GALE GUSTS IN THE NORTHER WATERS, THOUGH THE POTENTIAL FOR PROPER
GALES REMAINS LOW (AROUND 20 PERCENT). A MODERATE MID PERIOD
NORTHWEST SWELL WILL BUILD BEHIND THIS SYSTEM WITH OTHERWISE
MUCH MORE MODERATE CONDITIONS FOR THE WEEKEND. /JHW
HYDROLOGY
ALL MAIN STEM RIVERS ARE FORECAST TO REMAIN BELOW
MONITOR OR ACTION STAGE THROUGH MID WEEK. MINOR FLOODING OF
SMALLER RIVERS, CREEKS AND STREAMS WITH POOR DRAINAGE WILL BE
POSSIBLE. SOIL MOISTURE IS EXPECTED TO CONTINUE INCREASE OR SATURATE
LATE IN THE WEEK INTO THE WEEKEND WITH ADDITIONAL RAIN, INCREASING
THE RISK OF ROCKSLIDES AND MUDSLIDES, AND MINOR FLOODING. CHANCE
OF MAIN STEM RIVER STAGES EXCEEDING MONITOR STAGE WILL ALSO
INCREASE AS WE HEAD INTO THE FOLLOWING WEEK, DEC 22-28.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 11 AM PST TUESDAY FOR PZZ450.
SMALL CRAFT ADVISORY UNTIL 5 AM PST WEDNESDAY FOR PZZ470.
NOTE: THE FULL FORECAST DISCUSSION IS NOW REGULARLY ISSUED BETWEEN
10 AM/PM AND 1 PM/AM. ADDITIONAL UPDATES WILL BE ISSUED AS NEEDED.
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