735
FXUS66 KEKA 162122
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
222 PM PDT TUE SEP 16 2025
SYNOPSIS
HOT AND DRY WEATHER WILL PERSIST THROUGH WEDNESDAY
WITH GUSTY NEARSHORE WINDS. COOLER WEATHER, SCATTERED SHOWERS, AND
A SLIGHT CHANCE FOR THUNDERSTORMS WILL RETURN THURSDAY INTO THE
WEEKEND.
DISCUSSION
THE ENTIRE FORECAST AREA ENJOYED A BREAK FROM THE
STRATUS WITH AMPLE SUNSHINE TODAY. THE MARINE LAYER IS ATTEMPTING
TO REFORM, BUT IS STRUGGLING. MORE SUNSHINE IS FORECAST WEDNESDAY
WITH A WEAK INVERSION, WHICH SHOULD ALLOW FOR QUICK DAYTIME
CLEARING.
A QUICKLY AMPLIFYING RIDGE IS BRINGING SOME LATE SEASON HEAT.
INTERIOR VALLEY HIGHS WILL REACH THE UPPER 90S WITH SOME ISOLATED
LOW 100S FORECAST. THIS IS CREATING SOME ISOLATED MODERATE
HEATRISK THROUGH WEDNESDAY.
A REMNANT TROPICAL SYSTEM WILL BEGIN PUSHING IN MOISTURE FROM THE
SOUTH BY LATE WEDNESDAY. ELEVATED INSTABILITY WILL ACCOMPANY THIS
MOISTURE, WHICH WILL INITIALLY BE FOCUSED IN THE SOUTHERN ZONES
FROM LAKE COUNTY TO SOUTHERN MENDOCINO COUNTIES. THERE IS WIDE
UNCERTAINTY IN THE EXACT TRAJECTORY OF THE INITIAL MOISTURE
SURGE. SHOWERS AND A SLIGHT CHANCE FOR THUNDERTORMS MAY BEGIN JUST
OFF OR ALONG THE COAST OF MENDOCINO COUNTY LATE WEDNESDAY/EARLY
THURSDAY MORNING, BUT THE THURSDAY PERIOD HAS THE GREATEST
UNCERTAINTY WITH IT. SOUNDINGS SHOWED A GOOD DEAL OF CONVECTIVE
INHIBITION (CIN) THURSDAY, BUT SOUTHERN ZONES SUCH AS LAKE COUNTY
AND MENDOCINO COUNTIES MAY SEE SOME THUNDERSTORM DEVELOPMENT (10%).
PRECIPITAL WATER VALUES WILL BE HIGH (1 TO 1.6 INCHES), BUT THERE
WILL INITIALLY BE LESS PRECIPITATION REACHING THE GROUND FROM ANY
SHOWERS OR THUNDERSTORMS BEFORE THE DRYNESS AT THE LOWEST LEVELS
BEGINS TO SATURATE. COVERAGE MAY BE HIGHLY LIMITED DEPENDING ON
WHERE THE BEST MOISTURE AXIS SETS UP.
THE MOISTURE AND INSTABILITY WILL TO CONTINUE TO SPREAD IN FRIDAY
THROUGH SATURDAY WHEN PRECIPITATION TOTALS WILL INCREASE MORE
WITH DEEPER MOISTURE. A SURFACE LOW WILL FORM ALONG THE NORTH
COAST FRIDAY, AND THIS WILL INCREASE FORCING AND WORK TO WRAP THE
MOISTURE FARTHER WEST. THIS WILL CONTINUE TO BRING THE CHANCE FOR
SHOWERS AND ISOLATED THUNDERSTORMS THROUGH SATURDAY. THE EXACT
TIMING AND LOCATION OF THIS ACTIVITY WILL HAVE TO BE FURTHER
RESOLVED IN COMING HIGHER RESOLUTION GUIDANCE.
AVIATION
VFR CONDITIONS EXPECTED TO PERSIST TO ALONG THE COAST
WITH LIGHT NORTHERLIES. SATELLITE IMAGERY SHOWS A WEAK POOL OF
STRATUS OFF THE COAST OF HUMBOLDT AND MENDOCINO COUNTIES COULD
ARRIVE WITH FEW-SCT CEILINGS AS EARLY AS 22Z TODAY. TONIGHT, MODEL
GUIDANCE IS PUSHING FOR STRATUS TO REAPPEAR ALONG THE COAST TONIGHT
WITH A 50% PROBABILITY OF LIFR AND A 60% PROBABILITY OF IFR
CONDITIONS FOR THE NORTH COAST OVERNIGHT. TOMORROW MORNING, WINDS
WILL BEGIN TO INCREASE ALONG THE COAST, LEADING TO INCREASED MIXING
AT THE SURFACE AND A FASTER BREAK UP OF ANY STRATUS THAT DOES FORM
BY 16-18Z.
INLAND AREAS CAN EXPECT VFR CONDITIONS. CLEAR SKIES, CLEAN
VISIBILITIES, AND TERRAIN DRIVEN WINDS WITH THE OCCASIONAL GUST THIS
AFTERNOON AS WINDS MIXED DOWN NEAR RIDGES ARE TO BE EXPECTED ACROSS
THE ENTIRE FORECAST AREA. TOMORROW, THE INFLUENCE FROM TROPICAL
STORM MARIO WILL BEGIN TO IMPACT NW CALIFORNIA LEADING TO A CHANGE
IN THE WEATHER PATTERN.
MARINE
LIGHT WINDS AND DECAYING WIND WAVES DOMINATE THE COASTAL
WATERS TODAY. A CHANGE TO OUR SYNOPTIC WEATHER SETUP OVER THE NEXT
FEW DAYS CHANGES THE SEA STATE THROUGH THE END OF THE WEEK. HIGH
PRESSURE OFFSHORE INTERACTING WITH THE LOW PRESSURE INLAND WILL
DRASTICALLY ENHANCE THE PRESSURE GRADIENT CREATING STRONG, GALE
FORCE SUSTAINED WINDS WITH GUSTS OVER 45KTS POSSIBLE OVER THE OUTER
WATERS WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WIND WAVES OF 15FT OR
MORE ARE PROBABLE ACROSS THE NORTHERN WATERS AND SOUTHERN OUTER
WATERS.
HAZARDS HAVE BEEN ISSUED FOR ALL MARINE FORECAST ZONES. CURRENTLY
THERE ARE WATCHES IN PLACE FOR THE REST OF THE WEEK, AS TIMING
BECOMES BETTER REFINED IN FUTURE MODEL RUNS, THESE INNER WATER ZONES
OUT 10NM CAN EXPECT NEAR GALE GUSTS WITH LARGE WIND WAVES
PROPAGATING INTO THE WATERS. OUTER WATER ZONES 10-60NM CAN BE
SUBJECT TO GALE FORCE WINDS SOUTH OF CAPE BLANCO AND CAPE MENDOCINO
AND LARGE, VERY STEEP, WIND WAVES WITH BLOWING SPRAY.
WINDS BEGIN TO EASE SLIGHTLY THURSDAY NIGHT THROUGH FRIDAY MORNING
WITH WIND WAVES BEGINNING TO EASE FRIDAY AFTERNOON THROUGH SATURDAY
MORNING. THIS WEEKEND, A NW SWELL OF 5FT@11-13S IS EXPECTED WITH
WINDS BETWEEN 10-20KTS ACROSS ALL THE WATERS. GLOBAL DETERMINISTIC
MODELS ARE NOT ALIGNED AS TO WHAT THE SYNOPTIC SET UP WILL BE, YET
CLUSTER ANALYSIS INDICATES RELATIVELY ZONAL FLOW ALOFT WITH A CUTOFF
LOW OFF THE COAST OF CENTRAL CA. THIS WILL KEEP WINDS BREEZY, WIND
WAVES MILD, AND THE NW SWELL DECAYING. DS
FIRE WEATHER
UNSEASONABLY WARM AND DRY CONDITIONS WILL PERSIST
THROUGH WEDNESDAY AND WILL AID IN QUICKLY DRYING OUT FUELS.
INTERIOR VALLEY HIGHS WILL BE IN THE MID 90S WITH HUMIDITY AS LOW
AS THE UPPER TEENS. STRONG THERMAL BELTS WILL MAINTAIN POOR
OVERNIGHT RECOVERIES AT MID AND UPPER ELEVATIONS. WINDS WILL BE
MOSTLY GENTLE AND TERRAIN DRIVEN. NORTHEAST WINDS WILL BE BREEZING
FOR INTERIOR DEL NORTE COUNTY WEDNESDAY NIGHT THROUGH THURSDAY. A
SURGE OF BREEZY SOUTHWEST WINDS WILL BRIEFLY DEVELOP IN LAKE
COUNTY THURSDAY AFTERNOON WITH MINIMUM RH VALUES IN THE LOW TO MID
20S. DAYTIME TEMPERATURES WILL LOWER THURSDAY WITH MORE MOISTURE
AND CLOUD COVER ENTERING THE AREA. THERE WILL BE A SLIGHT CHANCE
(10%) OF SEMI-DRY THUNDERSTORMS THURSDAY AFTERNOON MOSTLY FOCUSED
AROUND THE YOLLA BOLLYS AND OVER MENDOCINO AND LAKE COUNTIES WITH
SOME SLIGHT POTENTIAL FURTHER NORTH. A SLIGHT CHANCE (20%) FOR
ADDITIONAL MORE RAINFALL PRODUCTIVE SHOWERS AND THUNDERSTORMS WILL
CONTINUE FRIDAY AND SATURDAY. STORMS WOULD HAVE MODERATE STORM
MOVEMENT AND WOULD BE RELATIVELY WET. THERE IS CURRENTLY HIGH
UNCERTAINTY IN THE EXACT DETAILS FOR SHOWERS OR ISOLATED
THUNDERSTORMS.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY FROM 11 PM WEDNESDAY TO 5 AM PDT
THURSDAY FOR PZZ450.
HAZARDOUS SEAS WATCH FROM LATE WEDNESDAY NIGHT THROUGH
THURSDAY EVENING FOR PZZ450.
SMALL CRAFT ADVISORY FROM 5 PM WEDNESDAY TO 5 AM PDT
THURSDAY FOR PZZ455.
SMALL CRAFT ADVISORY FROM 5 PM TO 11 PM PDT WEDNESDAY FOR
PZZ470.
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING
FOR PZZ470.
SMALL CRAFT ADVISORY FROM 5 AM TO 5 PM PDT WEDNESDAY FOR
PZZ475.
GALE WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
AFTERNOON FOR PZZ475.
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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