297
FXUS66 KEKA 312207
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
302 PM PDT MON MAR 31 2025
SYNOPSIS...GENERAL GUSTY WINDS, SHOWERS AND ISOLATED
THUNDERSTORMS WITH SMALL HAIL ARE EXPECTED TO CONTINUE THROUGH
TUESDAY ALONG WITH MODERATE TO HEAVY DOWNPOURS TODAY AND TUESDAY.
HEAVY MOUNTAIN SNOW ABOVE 3000 FEET ELEVATION IS ANTICIPATED
THROUGH TUESDAY, AS WELL. LINGERING SHOWERS THROUGH WEDNESDAY,
FOLLOWED BY DRY WEATHER FOR THE REMAINDER OF THE WEEK ARE
FORECAST.
SHORT TERM
THE SMALL HAIL THREAT CONTINUES TO BE VERIFIED THIS
AFTERNOON WITH NUMEROUS REPORTS RECEIVED THROUGHOUT THE DAY, AND
DRIVING CONDITIONS WILL BE VERY HAZARDOUS WHERE SMALL HAIL
ACCUMULATES. SOME OF THE STRONGER SHOWERS AND THUNDERSTORMS OVER
THE OCEAN WATERS SHOWED ROTATION AND POSSIBLY CONTAINED
WATERSPOUTS, AND THIS THREAT WILL ALSO PERSIST. A COLD UPPER
TROUGH IS MOVING IN TODAY, AND THE SHOWERS AND STORMS WITH SMALL
HAIL WILL BECOME A GREATER THREAT THIS EVENING THROUGH TUESDAY
AFTERNOON WITH THE COLDER AIR ALOFT AND STEEPER LAPSE RATES. THIS
TROUGH IS ALSO INCREASING WINDS AGAIN TONIGHT THROUGH TUESDAY. THE
SOUTHWESTERLY TO WESTERLY WINDS WILL REACH NEAR ADVISORY LEVEL
WIND WILL GUST FORM 35 TO 40 MPH AT THE EXPOSED HEADLANDS, WITH
HIGHER GUSTS ON SOME OF THE HIGHER RIDGES UP TO 50 MPH. THE
PREVALENT INSTABILITY GIVES BETTER CONFIDENCE TO THESE WINDS. THE
CURRENT WINTER STORM WARNING AND WINTER WEATHER ADVISORY IS ON TRACK
AND LEFT UNCHANGED. SOME ADJUSTMENTS MAY BE REQUIRED GIVEN
INDICATIONS THE SNOW LEVELS MAY BE SLIGHTLY LOWER THAN
THE CURRENT FORECAST HOLDS. JJW
AVIATION
TERMINALS HAVE BEEN PREDOMINANTLY VFR WITH PERIODIC
REDUCTIONS IN VSBY LESS THAN 3SM IN HEAVY SHOWERS MIXED WITH HAIL.
CEILINGS HAVE BEEN DIPPING DOWN TO MVFR (1500-2500 FT) IN THE
STRONGER CONVECTION AROUND SHOWERS. WINDS HAVE BEEN GENERALLY
SOUTHERLY WITH BRIEF BURSTS OF WESTERLY GUSTS UP TO 30 KT OR SO NEAR
SHOWER LINES MOVING ACROSS THE AREA. A BRIEF BREAK MAY FOLLOW INTO
EARLY THIS EVENING AS A DRY SLOT OFFSHORE BRINGS AN INCREASE IN
STABILITY. LEADINGS EDGE OF AN OPEN CELL CUMULUS FIELD AND PERHAPS
ANOTHER ORGANIZED LINE OF CONVECTION IS FORECAST TO MOVE THROUGH
LATER TONIGHT INTO EARLY TUE. A BROAD UPPER TROUGH WILL DRIVE THE
SURFACE LOW CLOSER TO THE COAST LATE TONIGHT, WITH A PERIOD OF LLWS
AND GUSTS EXCEEDING 30 KTS POSSIBLE ALONG THE NORTH COAST AFTER 00Z
AND OVER UKI OVERNIGHT. DB
MARINE
SHOWER AND THUNDERSTORM ACTIVITY PERSISTED OVER THE
COASTAL WATERS TODAY. WIND GUST REPORTS FROM THE BUOYS HAVE BEEN
UNDER 25 KT, BUT WITH STEEP WAVES OF 8-10 FT. ANOTHER FRONTAL
BOUNDARY WILL MOST LIKELY GENERATE ANOTHER RAMP UP OF WINDS THIS
EVENING AND OVERNIGHT. STRONGEST WINDS WILL LIKELY OCCUR ON THE
BACKSIDE OF THE TROUGH WITH WESTERLY GALE GUSTS UP TO 40 KT. HREF
PROBABILITIES FOR GUSTS OVER 35 KT ARE HIGHEST OVER THE OUTER
WATERS, BUT MAY EXTEND INSIDE 10NM AND ONTO THE COAST WITH STRONGER
CONVECTION. THE GALE WATCH FOR THE OUTER WATERS HAS BEEN UPGRADED TO
A GALE WARNING, THOUGH THE COVERAGE IS NOT 100% THROUGH THE
DURATION. A LARGER MID-PERIOD WESTERLY SWELL WILL FILL INTO THE
WATERS LATER TONIGHT AND PEAK NEAR 12-14 FT TUESDAY MORNING. SHORTER
PERIOD SW AND W WAVES AROUND 8 TO 10 SECONDS WILL COMBINE WITH THE
SWELL TO PRODUCE SIGNIFICANT WAVE HEIGHTS OF 15 TO 17 FEET BY
TUESDAY MORNING. CONFIDENCE IN A HAZARDOUS SEAS WARNING IS NOT HIGH
AT THE MOMENT DUE TO THE UNCERTAINTY IN THE WIND FORECAST AND STEEP
WAVE GENERATION. STEEP SEAS AND MODERATE NORTHERLY WILL PERSIST TUE
NIGHT-THU WITH LOW PROBABILITIES (LESS THAN 20% CHANCE) FOR GALE
GUSTS IN THE LEE OF CAPE MENDOCINO. NORTHERLY BREEZES AND SHOULD
SLACKEN UP TOWARD THE END OF THE WEEK AS LONG SWELL GROUP BEGINS TO
BUILD AND POTENTIALLY POSE A SNEAKER WAVE RISK. DB
PREV DISCUSSION
/ISSUED 430 AM PDT MON MAR 31 2025/
DISCUSSION...
KEY MESSAGES:
-CONTINUED SHOWERS AND GUSTY WINDS (GUSTS 25MPH TO 40MPH), WITH
ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL HAIL AROUND THE
COAST.
-PERIODS OF MODERATE TO HEAVY DOWNPOURS TODAY INTO EARLY TUESDAY.
-HEAVY MOUNTAIN SNOW ABOVE 3000 FEET FOR TRINITY AND HUMBOLDT
COUNTIES INTO MID DAY TUESDAY.
WEATHER PATTERN OVERVIEW:
AN AREA OF LOW PRESSURE CONTINUES ITS APPROACH TOWARD THE PACIFIC
NORTHWEST. SHOWERS CONTINUE TO MOVE THROUGH THE AREA EARLY THIS
MORNING. BY MID TO LATE MORNING, ANOTHER PUSH OF MOISTURE WILL
MOVE INTO NORTHWEST CALIFORNIA. PERIODS OF MODERATE TO HEAVY
RAINFALL AND THE CHANCE FOR ISOLATED THUNDERSTORMS WITH SOME
POTENTIAL FOR SMALL HAIL FOR COASTAL AREAS ARE EXPECTED AS COOLER
AIR INFILTRATES THE REGION. THIS COLDER DEEP-LAYER AIRMASS WILL
SUBSEQUENTLY SPREAD SOUTH ACROSS THE WEST COAST THROUGH TUESDAY.
THE COLD AIRMASS WILL AID IN STEEP LAPSE RATES AND AN INCREASINGLY
UNSTABLE ENVIRONMENT. ISOLATED THUNDERSTORMS, SMALL HAIL AND
BRIEF HEAVY DOWNPOURS WILL BE POSSIBLE WITH THE STRONGEST SHOWERS.
IN ADDITION, GUSTY SOUTHWEST WINDS FROM 25 TO 40 MPH ARE EXPECTED
ACROSS THE AREA LATE THIS AFTERNOON THROUGH TUESDAY AFTERNOON.
MOUNTAIN SNOW IMPACTS ARE LIKELY OVER TRINITY COUNTY AND NORTHERN
INTERIOR HUMBOLDT TODAY THROUGH TUESDAY AFTERNOON. SNOW LEVELS
WILL LIKELY DROP TO 3000 FEET TODAY. HEAVY SNOW, WITH STORM TOTAL
ACCUMULATIONS AT 7 TO 12 INCHES FOR ELEVATIONS ABOVE 3000 FEET,
WITH LOCALLY HIGHER AMOUNTS TO 1.5 FEET ACROSS THE HIGHER RIDGES,
ARE PROBABLE THIS MORNING THROUGH TUESDAY AFTERNOON. SNOW LEVELS
WILL BE GENERALLY ABOVE 3000 FEET. HOWEVER, UNCERTAINTY EXIST WITH
SNOW LEVELS DUE TO THE POSSIBILITY OF LOWER SNOW LEVELS DURING
CONVECTIVE SHOWERS. 2 TO 3 INCHES OF SNOW ARE EXPECTED FOR
ELEVATIONS AS LOW AS 2600 FEET. TRAVEL IMPACTS ARE EXPECTED ACROSS
MUCH OF HIGHWAY 3 NORTH OF WEAVERVILLE AND HAYFORK SUMMIT, HWY
JUNCTION 36 AND 3 AT SOUTH FORK MOUNTAIN, HWY 299 AT BERRY SUMMIT,
BUCKHORN SUMMIT AND OREGON MOUNTAIN.
LINGERING SHOWERS ARE EXPECTED THROUGH WEDNESDAY, FOLLOWED BY DRY
WEATHER FOR THE REMAINDER OF THE WEEK AS A LARGE SCALE UPPER LEVEL
RIDGE GRADUALLY BUILDS ACROSS THE REGION IN THE WAKE OF THE
TROUGH.
FORECAST CONFIDENCE AND DEVIATIONS:
RAIN TODAY COULD BE HEIGHTENED DUE TO INCREASED POTENTIAL FOR
CONVECTION, POSSIBLY CREATING INCREASED RAIN RATES AND A SMALL
HAIL THREAT. BY VERY EARLY WEDNESDAY MORNING, COLD AIR ALOFT COULD
ALLOW FOR LOWER SNOW LEVELS ACROSS NW CALIFORNIA. MODELS
CURRENTLY SHOW A STRONG DIURNAL PATTERN WITH SNOW LEVELS DIPPING
TO AROUND 2500 FEET AT NIGHT (NBM) AND JUMPING ABOVE 3000 FEET
DURING THE DAY. ANY SNOW THAT FALLS AT LOWER ELEVATIONS WILL BE
VERY INCONSISTENT AND LIKELY NOT VERY IMPACTFUL.
AVIATION...COASTAL TERMINALS ARE PREDOMINANTLY VFR/MVFR WITH PERIODIC
REDUCTIONS IN VIZ/CEILINGS WITH CONVECTIVE RAIN SHOWERS AND GUSTY
SSW WINDS. A SLIGHTLY QUIETER PERIOD IS EXPECTED THROUGH SUNRISE
BEFORE MORE WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS DEVELOP
FROM OFFSHORE AND CONTINUE THROUGH THE DAY. SIMILAR FLUCTUATING
CONDITIONS ARE EXPECTED AT ALL TERMINALS WITH GUSTY SW WINDS,
ESPECIALLY AT CEC. A BROAD UPPER TROUGH WILL DRIVE THE SURFACE LOW
CLOSER TO THE OR/WA COAST LATE THIS AFTERNOON AND EVENING, WITH A
PERIOD OF LLWS AND GUSTS EXCEEDING 30 KTS POSSIBLE ALONG THE NORTH
COAST AFTER 00Z.
MARINE...SMALL CRAFT WINDS AND SEAS CONTINUE ACROSS ALL ZONES AS A
SURFACE LOW SPINS OFF THE OR/WA COAST. SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ARE EXPECTED THROUGH TUESDAY, OCCASIONALLY
PRODUCING GUSTY AND ERRATIC WINDS AND LOCALLY HEAVY DOWNPOURS. AS
THE LOW NEARS THE COAST, NEAR GALE TO GALE GUSTS ARE EXPECTED IN THE
OUTER WATERS OVERNIGHT INTO EARLY TUESDAY. A GALE WATCH HAS BEEN
EXTENDED TO THE SOUTHERN OUTER WATERS DUE TO UNCERTAINTY ON THE
COVERAGE OF THESE WINDS. A LARGE MID-PERIOD WESTERLY SWELL WILL FILL
INTO THE WATERS DURING THE SAME TIME PERIOD, PEAKING EARLY TUESDAY
MORNING. SIGNIFICANT WAVE HEIGHTS 15 TO 17 FEET ARE POSSIBLE BEFORE
QUICKLY DIMINISHING BELOW ADVISORY LEVELS BY WEDNESDAY.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
WINTER WEATHER ADVISORY UNTIL 5 PM PDT TUESDAY FOR CAZ105.
WINTER STORM WARNING UNTIL 5 PM PDT TUESDAY FOR CAZ107-108.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 3 AM PDT WEDNESDAY FOR PZZ450-
455.
SMALL CRAFT ADVISORY UNTIL 6 PM PDT THIS EVENING FOR PZZ470-
475.
GALE WARNING FROM 6 PM THIS EVENING TO 8 AM PDT TUESDAY FOR
PZZ470-475.
HAZARDOUS SEAS WARNING FROM 8 AM TO 1 PM PDT TUESDAY FOR
PZZ470.
HAZARDOUS SEAS WARNING FROM 8 AM TO 5 PM PDT TUESDAY FOR
PZZ475.
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