544
FXUS66 KEKA 282210
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
310 PM PDT MON APR 28 2025
SYNOPSIS
DRY CONDITIONS ARE ANTICIPATED TODAY AS RIDGING BUILDS
ALOFT. A QUICK PASSING TROUGH WILL BRING INCREASED CLOUD COVER
AND A SLIGHT CHANCE FOR MOUNTAIN SHOWERS ON TUESDAY. DRY WEATHER
RETURNS ON WEDNESDAY WITH TEMPERATURES WARMING WELL ABOVE NORMAL
THROUGH THURSDAY.
DISCUSSION
DRY NORTHERLY FLOW IS PROMOTING ABUNDANT CLEAR SKIES
ACROSS NORTHWEST CALIFORNIA THIS AFTERNOON. INTERIOR HIGH TEMPERATURES
ARE 5 TO 15 DEGREES WARMER THAN YESTERDAY'S READING, WITH HIGHS
IN THE MID 60'S TO MID 70'S. COASTAL AREAS HIGHS PERSISTING THE
50'S DUE TO THE SEA BREEZES. BREEZY NORTHWESTERLY WINDS WITH GUSTS
FROM 25 TO 35 MPH HAVE BEEN OBSERVED ALONG THE NORTH COAST, WITH
LOCALLY STRONGER WINDS OVER THE EXPOSED RIDGES IN CAPE MENDOCINO.
WINDS ARE EXPECTED TO DECOUPLE THIS EVENING.
FOR TONIGHT, COASTAL CLOUDS WILL REDEVELOPED IN THE VICINITY OF
HUMBOLDT BAY AND PORTIONS OF THE MENDOCINO COAST, BEFORE EXPAND
AGAIN INTO TUESDAY MORNING.
A WEAK SHORTWAVE TROUGH WILL MOVE SOUTHEAST ACROSS THE AREA ON
TUESDAY. MID TO HIGH LEVEL CLOUDS WILL INCREASE AHEAD OF THE
SHORTWAVE. A SHALLOW ELEVATED INSTABILITY IS EXPECTED TO OCCUR
ACROSS THE EASTERN PORTION OF TRINITY AND AROUND THE YOLLA BOLLY
TUESDAY AFTERNOON. HOWEVER, GFS AND NAM MODEL SOUNDINGS DEPICT A WELL-
DEFINED CAP THAT COULD INHIBIT CONVECTION OVER MOST OF OUR CWA.
TEMPERATURES ARE FORECAST TO BE SIMILAR LIKE TODAY, MONDAY.
RIDGING WILL ONCE AGAIN BUILD BACK OVER THE WEST COAST ON WEDNESDAY
BRINGING WARM TEMPERATURES TO THE INTERIOR WITH HIGH TEMPS IN VALLEY
LOCATIONS EXCEEDING 80 DEGREES IN SOME LOCATIONS. AFTER MORNING
COASTAL STRATUS AND VALLEY FOG, ABUNDANT CLEAR SKIES ARE EXPECTED.
500MB PATTERN ON THURSDAY WILL RESEMBLE A REX BLOCK. A POSITIVE
HEIGHT ANOMALY WILL REMAIN CENTERED OVER THE PAC NW (WASHINGTON
AND OREGON) AND EXTEND SOUTHWARD INTO NORTHERN CALIFORNIA. A CUT-
BACK TROUGH OR CLOSED 500MB CYCLONIC CIRCULATION OFFSHORE OR OVER
CENTRAL/SOUTHERN CALIFORNIA WILL COMPLETE THE REX-BLOCK PATTERN.
IT IS POSSIBLE FOR WRAP AROUND MOISTURE FROM THE CLOSED LOW TO
SPREAD OVER LAKE AND EASTERN MENDOCINO FOR DIURNAL CONVECTION. ALL
6-HOURLY ENSEMBLE MEMBERS FROM THE ENS, GEFS AND CMCE INDICATE NO
PRECIP. ALSO, NBM PROBABILITIES FOR THUNDERSTORMS > 15% ARE WELL
TO THE EAST AND SOUTHEAST; OVER THE SIERRA NEVADA MTN RANGE.
INTERIOR HIGH TEMPERATURE WILL REMAIN ABOVE AVERAGE ON THU UNDER
LARGE SCALE ADIABATIC WARMING FROM THE RIDGE CENTERED OVER THE PAC
NW. HIGH TEMPS IN THE MID 70'S TO MID 80'S ARE GENERALLY
EXPECTED, HOWEVER A FEW HOT SPOTS SUCH BIG BAR RAWS WILL PROBABLY
EXCEED 90F. /ZVS
EXTENDED DISCUSSION...FRIDAY THROUGH SUNDAY
GET READY FOR MORE COOL AND WET WEATHER. A 500MB TROUGH WILL DIG
SOUTHWARD FROM THE GULF OF ALASKA AND APPROACH NW CAL ON FRIDAY.
ALL DETERMINISTIC MODELS, GFS, ECMWF, GDPS, ICON AS WELL AS
ENSEMBLE MEANS WERE IS GOOD AGREEMENT WITH DRIVING A FRONTAL
BOUNDARY ACROSS THE NORTHERN PORTION OF THE AREA ON FRIDAY.
24-HOUR ENSEMBLE CLUSTER MEANS CONTINUE TO DEPICT SUBTLE
DIFFERENCES WITH PLACEMENT, TIMING AND OVERALL EVOLUTION OF THE
COLD CORE ALOFT. ABOUT 30-45% OF CLUSTER MEMBERS CONTINUE TO TREND
WETTER THAN THE GRAND ENSEMBLE MEAN. NBM CONTINUES TO INDICATE
50-70% CHANCES FOR 0.25IN OF RAIN IN 24 HOURS FRIDAY- SATURDAY IN
DEL NORTE, 30-50% CHANCES FOR HUMBOLDT, 20-45% CHANCES OF TRINITY
AND 10-25% CHANCES FOR MENDOCINO AND LAKE. BY 5AM SAT, OVER HALF
AN INCH WILL BE POSSIBLE (50% CHANCE) FOR INTERIOR DEL NORTE. NOT
A MAJOR RAIN EVENT BY ANY STRETCH BUT WET WEATHER WILL IMPACT
OUTDOOR ACTIVITIES AND PROJECTS. SPRING SNOWFALL WILL ALSO BE
POSSIBLE ABOVE 4000-4500 FEET WITH 1 TO 2 INCHES OF STORM TOTAL
ACCUMULATION BY 5 AM SUNDAY.
INTERIOR TEMPERATURES WILL BE CONSIDERABLY COOLER AND WELL BELOW
NORMAL AGAIN NEXT WEEKEND (SAT MAY 3 AND SUN MAY 4). THERE MIGHT
EVEN BE POCKETS OF MORNING FROST IN THE INTERIOR VALLEYS WITH MIN
TEMPS BELOW 36F. PRECIP CHANCES GENERALLY DIMINISH AS WE HEAD INTO
DAY 7 (SUNDAY) AS THE TROUGH HEADS SOUTHWARD AND EASTWARD. TO WHAT
EXTENT AND HOW FAST THIS OCCURS ARE STILL NOT 100% CERTAIN. PRECIP
COULD WRAP BACK AROUND A POTENTIAL CUT-OFF LOW OR AN UPSTREAM KICKER
MAY KNOCK DOWN THE OFFSHORE RIDGE RESULTING IN MORE LIGHT PRECIP
FROM THE WEST. A FASTER SEWRD PROGRESSION WITH STRONGER RIDGING
OFFSHORE WOULD RESULT IN A MUCH DRIER AND GUSTY NORTH/NORTHWEST WIND
SCENARIO FOR OUR FORECAST AREA. MOST ENSEMBLE MEMBERS SUPPORT THIS
SCENARIO. STAY TUNED. /DB
AVIATION
HIGH PRESSURE BUILDING INTO THE AREA HAS BROUGHT MOST
CLEAR SKIES AND VFR CONDITIONS. BREEZY CONDITIONS ARE IN PLACE AT
THE COAST AND ON THE COASTAL RIDGES WITH LIGHTER WINDS IN THE
VALLEYS. TONIGHT STRATUS IS EXPECTED TO RETURN ALONG THE COAST IN
THE IN THE NEAR COASTAL RIVER VALLEYS. THE HREF SHOWS THIS RETURNING
QUICKLY IN THE EVENING. AS OF 230PM THERE ARE STILL CLOUDS AROUND
KNEELAND AND FRESHWATER. ONCE THE SUN GOES DOWN THESE ARE EXPECTED
TO QUICKLY EXPAND. THEY ARE NOT EXPECTED TO MAKE IT AS FAR UP THE
RIVER VALLEYS AS THEY DID THIS MORNING. KCEC IS EXPECTED TO STAY
CLEAR WITH SOME OFFSHORE FLOW IN DEL NORTE COUNTY, BUT CONFIDENCE IS
LOW ON THIS. CLEARING IS EXPECTED BY LATE MORNING MIDDAY AGAIN
TOMORROW. MKK
MARINE
HIGH PRESSURE OVER THE AREA IS EXPECTED TO BRING
NORTHERLY WINDS THROUGH WEDNESDAY. WINDS ARE PEAKING THIS AFTERNOON
AND EVENING WITH NEAR GALE TO GALE FORCE WINDS OVER MUCH OF THE
WATERS. STEEP WAVES WILL PEAK AROUND 9 TO 12 FEET. TONIGHT THESE
WINDS WILL DIMINISH SLIGHTLY, BUT REMAIN AROUND 20 TO 25 KT IN THE
OUTER WATERS AND SLIGHTLY LOWER AT NIGHT CLOSER TO THE COAST.
THURSDAY A WEATHER SYSTEM APPROACHING THE AREA WILL DIMINISH THESE
WINDS MORE. WINDS FRIDAY WILL MAY BRIEFLY TURN SOUTHERLY AT LEAST IN
THE NORTHERN WATERS. SATURDAY AND SUNDAY NORTHERLY WINDS RETURN AND
THEY MAY BE NEAR GALE OR GALE FORCE AGAIN. WAVES WILL CONTINUE TO BE
MAINLY WIND DRIVEN THROUGH MUCH OF THE WEEK. FRIDAY A 16 SECOND
SWELL IS EXPECTED TO BUILD TO AROUND 4 OR 5 FEET. MKK
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 9 PM PDT TUESDAY FOR PZZ450-455-
470.
GALE WARNING UNTIL 11 PM PDT THIS EVENING FOR PZZ475.
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