865
FXUS66 KEKA 252210
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
310 PM PDT FRI APR 25 2025
SYNOPSIS
SHOWERS ACTIVITY WILL INCREASE THIS EVENING. SCATTERED
TO NUMEROUS SHOWERS ACROSS THE AREA THROUGH SATURDAY, WITH
LINGERING SHOWERS THROUGH SUNDAY MORNING. BREEZY NORTHWEST WINDS
WILL DEVELOPED ALONG THE COAST AND EXPOSED RIDGES SATURDAY THROUGH
SUNDAY. DRY AND WARMING TREND SUNDAY THROUGH MID NEXT WEEK.
DISCUSSION
A CLOSED LOW CENTER LOCATED JUST NEAR 39N AND 127W
CONTINUE TO TRACK SOUTHEAST TOWARD CENTRAL CALIFORNIA THROUGH
SATURDAY. THIS IS PROMOTING ABOVE NORMAL MOISTURE VALUES ACROSS
ACROSS NORTHWEST CALIFORNIA, ESPECIALLY ALONG THE NORTH COAST THIS
AFTERNOON. DIURNAL HEATING ARE PROMOTING ISOLATED SHOWERS ARE
ALREADY AROUND THE YOLLA BOLLY. THERE IS SOME SHALLOW INSTABILITY
THIS AFTERNOON WITH A COLD AIR ALOFT OVER TRINITY CAPABLE OF PRODUCE
MODERATE SHOWERS BANDS. FOR THE REST OF THE DAY, SHOWERS ACTIVITY
ARE EXPECTED TO INCREASE IN COVERAGE THIS EVENING WITH INCREASING
LOW TO MID LEVEL MOISTURE AS THE AFOREMENTIONED LOW MOVES CLOSER.
EXPECT SCATTERED TO NUMEROUS SHOWERS ACROSS THE AREA THROUGH
SATURDAY, WITH PERIODS OF MODERATE RAIN RATES. PRECIPITATION WILL
TAPPER OFF FROM NORTH TO SOUTH SATURDAY EVENING AS THE TROUGH
EJECT THE AREA, WITH LINGERING SHOWERS THROUGH SUNDAY MORNING.
SATURDAY'S HIGH TEMPERATURES ARE FORECASTED TO BE 5 TO 15 DEGREES
BELOW NORMAL. ECMWF EXTREME FORECAST INDEX (EFI) HIGHLIGHT HIGHS
IN THE 60TH-80TH PERCENTILE BELOW NORMAL TEMPERATURES ON SATURDAY,
ESPECIALLY FOR THE INTERIOR AREAS IN SOUTHERN HUMBOLDT, INTERIOR
MENDOCINO AND LAKE COUNTY. OVERNIGHT TEMPERATURES ARE EXPECTED TO
REMAIN IN THE 40S ACROSS THE VALLEYS DUE TO LINGERING LOW LEVEL
MOISTURE.
BREEZY NORTHWEST WINDS WILL DEVELOPED ALONG THE COAST SATURDAY
AFTERNOON THROUGH SUNDAY AS A SURFACE HIGH PRESSURE BEGIN TO
BUILDS IN AND TIGHTEN THE PRESSURE GRADIENT. GUSTS FROM 25 TO 35
MPH ARE FORECAST FOR THE COASTAL HEADLANDS AND EXPOSED RIDGES,
WITH STRONGEST WINDS OVER THE MORE PROMINENT EXPOSED TERRAIN. HREF
PROBABILITIES INDICATES THERE IS A 50 TO 75% CHANCE OF WIND GUSTS
GREATER THAN 30 MPH FOR THE NORTH COAST SATURDAY EVENING, THEN
INCREASING CHANCE UP TO 50% ACROSS THE MENDOCINO COAST LATE
SATURDAY NIGHT.
SUNDAY, CLEARING SKIES ARE EXPECTED AND TEMPERATURES WILL START
TO WARM BACK UP AGAIN AS A HIGH PRESSURE BEGIN TO BUILDS IN
DOWNSTREAM IN THE WAKE OF THE TROUGH. INLAND AREAS ARE EXPECTED TO
SEE HIGHS IN THE 60S. AREAS OF VALLEY FOG ARE EXPECTED TO DEVELOP
SUNDAY NIGHT INTO MONDAY. HIGH PRESSURE CONTINUES TO BUILD IN
THROUGH THE WEEK WITH HIGHS AROUND 80 FOR THE INLAND AREAS BY
WEDNESDAY.
ENSEMBLE CLUSTERS AND DETERMINISTIC MODELS SHOWS THE HIGH PRESSURE
SHIFTING EASTWARD ON THURSDAY. MOST OF THE CLUSTER MEMBERS (78%)
SUGGEST AN UPPER LEVEL TROUGH APPROACHING THE AREA NEXT FRIDAY. HOWEVER,
THERE IS UNCERTAINTIES WITH THE POSITION OF THE LOW AND IF THERE
WILL BE ANY IMPACTS TO OUR AREA. ZVS
AVIATION
A DEEP MARINE LAYER WITH TOPS UP TO 3500 FEET IS
FORECAST TO PERSIST TONIGHT INTO FRIDAY. MVFR CEILINGS ARE FORECAST
TO PREVAIL, HOWEVER SHALLOW MOISTURE AAD NORTHWESTERLY SURFACE FLOW
WILL LIKELY YIELD PERIODS OF IFR CONDITIONS IN LIGHT PRECIP TONIGHT
INTO FRIDAY MORNING FOR COASTAL AERODROMES. CUMULUS CONVECTION AND
POSSIBLE THUNDERSTORMS ARE ALSO EXPECTED OVER THE INTERIOR THIS
AFTERNOON AND EARLY EVENING. WRAP AROUND MOISTURE AND RAIN MAY ALSO
RESULT IN MVFR CONDITIONS (20% CHANCE) LATER TONIGHT/FRIDAY FOR
LOCATION OUTSIDE AERODROME AIRSPACE. DB
MARINE
WAVE SPECTRUM REMAINED HEAVILY SKEWED TOWARD SHORTER
PERIOD BANDS (LESS 8 SECONDS) TODAY. MULTIPLE MID PERIOD WAVE BANDS
WERE ALSO PRESENT, CENTERED NEAR 14 AND 11 SECONDS. LONGER PERIOD W
AND SW SWELL GROUPS (>15 SECONDS) WERE CONTRIBUTING MUCH LESS TO THE
TOTAL SEA STATE WHICH HAS BEEN FLUCTUATING NEAR 5 FT. A LIGHTER NW
WIND REGIME (5 TO 15 KT) IS FORECAST TO CONTINUE FOR TONIGHT AND
FRIDAY WITH STEEP SEAS CONTINUING ON A DOWNWARD TREND.
A WEAK SURFACE LOW AND COLD FRONTAL SYSTEM WILL APPROACH THE OUTER
WATERS TONIGHT AND CONTINUE TO WEAKEN THE PRESSURE GRADIENT ACROSS
NW CALIFORNIA WATERS. LIGHTER WINDS AROUND 5 TO 15 KT WITH SEAS 5 FT
OR LESS ARE FORECAST ON FRIDAY. IN THE WAKE OF THE FRONTAL SYSTEM,
NORTHERLY WINDS WILL BEGIN TO INCREASE FRIDAY NIGHT THROUGH SATURDAY
AS HIGH PRESSURE BUILDS EASTWARD TOWARD THE OUTER WATERS. PRESSURE
GRADIENTS TIGHTEN SOME BY SATURDAY, HOWEVER THERE ARE CONSIDERABLE
DIFFERENCES BETWEEN THE MODELS AND THE RATE AT WHICH NORTHERLY WINDS
INCREASE SATURDAY. NBM PROBABILITY FOR WIND GUSTS > 25 KT INCREASE
TO 60-70% ON SATURDAY, HIGHEST IN THE OUTER WATERS AND DOWNWIND OF
CAPE MENDOCINO. WIND GUSTS UP TO 30 KTS ARE EXPECTED BY SUNDAY OVER
THESE SAME AREAS. OUR SPRING TIME NORTHERLY WIND REGIME WILL RETURN
THIS WEEKEND AND CONTINUE INTO AT LEAST EARLY NEXT WEEK. THERE IS A
CHANCE FOR GALE FORCE GUSTS OVER 34 KTS (40% CHANCE) ON MONDAY,
MAINLY FOR THE AFTERNOON SOUTH OF CAPE MENDOCINO. THE DURATION AND
COVERAGE APPEARS QUITE LIMITED AND NO HIGHLIGHTS ARE NECESSARY. DB
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 3 PM SATURDAY TO 9 AM PDT SUNDAY
FOR PZZ450-455-470-475.
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