925
FXUS66 KEKA 252155
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
238 PM PDT THU APR 25 2024
SYNOPSIS
PERIODS OF LIGHT TO MODERATE RAIN ARE FORECAST TONIGHT
THROUGH FRIDAY. DRIER AND COOLER CONDITIONS ARE EXPECTED FOR THE
WEEKEND EXCEPT FOR A SLIGHT CHANCE OF LIGHT RAIN NORTH OF CAPE
MENDOCINO SATURDAY AFTERNOON AND EVENING.
DISCUSSION
UPPER TROUGH OFFSHORE/OVER THE PAC NW IS FORECAST
TO DIG SOUTHEASTWARD TONIGHT AND THEN INTO NORTHERN GREAT BASIN
ON FRIDAY. THIS WILL LEAVE NW CALIFORNIA IN A MOIST NORTHWESTERLY
ONSHORE/UPSLOPE FLOW WITH PWAT ANOMALIES ABOUT 125-150% OF NORMAL.
GREATEST PRECIP AMOUNTS (1-2 INCHES) ARE FORECAST TO OCCUR ACROSS
INTERIOR DEL NORTE OVER 2 DAYS (TODAY- FRIDAY). MUCH LESS IS
EXPECTED FOR MENDOCINO, LAKE AND EASTERN TRINITY WHERE ONLY A FEW
HUNDREDTHS OR NOTHING IS FORECAST. LIGHT SNOW IS ALSO EXPECTED FOR
ELEVATIONS ABOVE 5500-6000 FEET WITH AROUND 1-4 INCHES FOR THE
HIGHEST PEAKS TODAY THROUGH FRIDAY. OVERALL, NOT A MAJOR PRECIP
MAKER BY ANY MEANS, BUT CERTAINLY ENOUGH TO PUT A DAMPER ON OUTDOOR
ACTIVITIES. THE TROUGH WILL ALSO INDUCE STRONGER NW WINDS, MAINLY
ACROSS LAKE AND PERHAPS EASTERN TRINITY/EASTERN MENDOCINO THIS
EVENING AND AGAIN ON FRIDAY. W-NW WIND GUSTS TO 30 TO 40 MPH FOR THE
WIND-PRONE EXPOSED RIDGES ARE HIGHLY PROBABLE (>60% CHANCE).
SUBFREEZING TEMPERATURES ARE HIGHLY PROBABLE (80% CHANCE) FOR THE
MOUNTAINS ABOVE 3500-4000 FEET FRIDAY NIGHT AND SATURDAY MORNING.
PROBABILITIES FOR VALLEYS TO FREEZE ARE MUCH LESS CERTAIN WITH
ONLY A 30-40% CHANCE FOR THE TYPICAL COLD VALLEYS IN TRINITY;
RUTH, HAYFORK, MAD RIVER, COFFEE CREEK & CARRVILLE. DINSMORE
RIGHT ALONG THE TRINITY/HUMBOLDT BORDER MY GET CLOSE TO 32F TOO.
FOG AND LOW CLOUDS WILL FORM IN THE VALLEYS AND HINDER THE
LONGWAVE COOLING. SOME INTERIOR VALLEYS IN MENDO, DEL NORTE, LAKE
AND HUMBOLDT ARE FORECAST TO DIP DOWN TO THE MID 30'S, SO IT WILL
START OFF CHILLY (FOR LATE APRIL) ON SATURDAY.
OTHERWISE, BROAD AND FLAT RIDGING IS FORECAST TO BUILD OFFSHORE
AS ANOTHER SHORTWAVE TROUGH PROGRESSES INTO THE PAC NW OVER THE
WEEKEND INTO EARLY NEXT WEEK. THIS LOW-AMPLITUDE WESTERLY FLOW
WILL MOST LIKELY KEEP TEMPERATURES ON THE MILD SIDE AND SLIGHTLY
BELOW OR NEAR SEASONAL NORMALS THROUGH EARLY NEXT WEEK.
MID TO LATE WEEK (WED AND THU) CONSIDERABLE UNCERTAINTY GROWS
REGARDING PRECIP CHANCES (TIMING AND AMOUNTS) AS ANOTHER TROUGH
DROPS DOWN FROM THE NW. ONCE AGAIN, HIGHEST PRECIP CHANCES WILL BE
NORTH OF CAPE MENDOCINO WITH THE LOWEST SOUTH. TEMPERATURES WILL
MOST LIKELY TREND DOWN AFTER A BRIEF WARM UP MON AND TUE. DB
AVIATION
COASTAL TERMINALS: A WEAK FRONTAL SYSTEM IS BRINGING
LIGHT RAIN AND SHOWERS TO REGION TODAY. CEILINGS WILL CONTINUE TO
ENTER MVFR TO TEMPO IFR LEVELS THIS AFTERNOON. PROBABILITY FOR
MORE CONSISTENT IFR IS HIGHEST FROM 1Z TO 6Z. DYNAMIC ENSEMBLE
BASED GUIDANCE TAKES IT DOWN TO LIFR AT ACV, BUT CONFIDENCE IS NOT
HIGH ON THAT CURRENTLY. THE COASTAL SOUTHERLY WINDS OF 10 TO 15
KTS WINDS WILL SUBSIDE THIS EVENING. CEILINGS WILL LIFT SOME
FRIDAY MORNING, BUT PROBS FOR AT LEAST TEMPO MVFR CONDITIONS WILL
REMAIN THROUGH THIS TAF PERIOD.
UKI: WINDS ARE FROM A MORE NORTHERLY DIRECTION AND PRODUCING OCNL
GUSTS. THE WEAK FRONT WILL PRODUCE VCSH TO -SHRA INTO THE VALLEY TO
LOWER CIGS TO MVFR LEVEL TONIGHT, WITH HEIGHTS POSSIBLY NEARING IFR
INTO EARLY FRIDAY MORNING. LIFTING AND A TRANSITION TOWARDS VFR IS
EXPECTED TOWARDS THE END OF THE TAF PERIOD. /JJW
MARINE
SOUTHERLY WINDS UP TO 15 KT WILL PROGRESS THROUGH THE
WATERS THIS EVENING WITH THE PASSAGE OF A WEAK FRONT. LIGHT, WESTERLY
WINDS BEHIND THE FRONT WILL SHIFT NORTHERLY AND INCREASE FRIDAY,
MAINLY IN THE SOUTHERN WATERS WHERE SMALL CRAFT ADVISORY LEVEL
WINDS AND SEAS ARE EXPECTED. OTHERWISE, THE ONGOING WNW SWELL AT
10 - 11 SECONDS WILL GRADUALLY EASE BELOW 10 SECONDS WITH WAVE
HEIGHTS AROUND 6 - 8 FEET THROUGH SATURDAY. A LONGER PERIOD WNW
SWELL WILL ARRIVE SATURDAY MORNING AROUND 14 SECONDS WITH SMALLER
WAVE HEIGHTS AROUND 2 - 3 FEET. MONDAY EVENING LOOKS TO HAVE NEAR
GALE GUSTS SOUTH OF CAPE MENDOCINO WHICH WILL LAST THROUGH TUESDAY
EVENING. EYS/JJW
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 3 AM SATURDAY TO MIDNIGHT PDT
SATURDAY NIGHT FOR PZZ455-475.
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