428
FXUS66 KEKA 160746
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1246 AM PDT TUE JUN 16 2026
SYNOPSIS
MODERATE TO MAJOR HEATRISK WILL CONTINUE ACROSS THE
INTERIOR THROUGH TUESDAY, THOUGH COASTAL AREAS WILL STILL SEE MARINE
INFLUENCE AND COOLING. THE HEAT WAVE WILL BREAK DOWN BEGINNING
WEDNESDAY.
KEY MESSAGES
- TEMPERATURES BEGIN TO SLIGHTLY EASE BUT REMAIN ABOVE AVERAGE
TUESDAY.
- COOLING TREND BEGINNING TO BUILD IN WEDNESDAY.
- SLIGHT (15%) THUNDERSTORM CHANCES OVER THE EASTERN INTERIOR
THURSDAY AND FRIDAY AFTERNOONS.
DISCUSSION
HIGH PRESSURE RIDGING CONTINUES TO DOMINATE ACROSS THE
AREA WITH THE STRONGEST FOCUS PERSISTING OVER HUMBOLDT AND TRINITY
COUNTIES TODAY WITH VALLEY HIGH TEMPERATURES AGAIN AROUND 100. HIGH
TEMPERATURES WILL CONTINUE TO BE ABOVE AVERAGE, THOUGH NOT RECORD
BREAKING. HIGH TEMPERATURES REBOUND AGAIN TODAY FOR THE SOUTHERN
HALF OF THE AREA THANKS TO WEAKENED SOUTH WIND. UKIAH RETURNED TO
NEAR 100 MONDAY AFTERNOON. CONDITIONS WILL EASE BY JUST A COUPLE
DEGREES TUESDAY, BUT THESE TEMPERATURES STILL CONSTITUTE A GENERALLY
MODERATE HEATRISK WITH SOME AREAS OF MAJOR RISK FOR THE WARMEST
VALLEYS. HEAT HAS MADE FOR A ROBUST BUT VERY SHALLOW MARINE LAYER
THAT HAS BLANKETED THE IMMEDIATE COAST, THOUGH CLEARING MONDAY WAS
SLIGHT BETTER THAN SUNDAY.
HIGH PRESSURE WILL BEGIN TO WEAKEN MORE BY WEDNESDAY WITH INTERIOR
HIGHS PULLING BACK INTO THE MID 80S. MOST DETERMINISTIC MODELS SHOW
WEAK TROUGH PUSHING ONSHORE AROUND THURSDAY. THIS TROUGH WILL
DEFINITELY COOL CONDITIONS AND HELP DEEPEN MARINE INFLUENCE ALONG
SHORE, CREATING A MORE PERSISTENT AND FURTHER REACHING MARINE LAYER.
COMPARED TO PREVIOUS RUNS, MORE HIGH RESOLUTION MODELS SHOW A
WEAK MOISTURE PLUME MOVING UP THE SACRAMENTO VALLEY. INTERACTING
WITH THE TROUGH, THIS COULD (20% CHANCE) PRODUCE ELEVATED, MOSTLY
DRY THUNDERSTORMS IN EASTERN MENDOCINO AND TRINITY COUNTIES ON
THURSDAY AND FRIDAY AFTERNOONS. /JHW
AVIATION
THOUGH BRIEF, THE COASTAL STRATUS SHOWED THE
FIRST SIGNS OF WEAKNESS MONDAY WITH PERIODS OF SCATTERING. SOUTHERLY
RETURN FLOW OVER THE COASTAL WATERS CONTINUES TO REPLENISH STRATUS
MASS FROM THE UNLIMITED SUPPLY BEING GENERATED OVER THE PACIFIC.
LIFR CONDITIONS AND AREAS OF FOG REMAINED OVER THE COASTAL TERMINALS
MONDAY NIGHT.
HIGH PRESSURE OVERHEAD STRENGTHENS OVERNIGHT, AND THE MARINE LAYER
WILL FURTHER COMPRESS TO VERY SHALLOW LEVELS THROUGH TUESDAY
MORNING. HIGH PRESSURE THEN WEAKENS TUESDAY, AND THE NORTHERLY WINDS
INCREASE. THIS WILL FINALLY ALLOW FOR TURBULENT MIXING TO SCOUR OUT
THE STRATUS THROUGHOUT DAY NORTH OF CAPE MENDOCINO, THOUGH A QUICK
RETURN IS EXPECTED GOING INTO TUESDAY EVENING. WEAKER NORTHERLY
WINDS SOUTH OF THE CAPE WILL CREATE AND SOUTHERLY EDDY WHICH WILL
KEEP THE STRATUS OVER OR ALONG THE MENDOCINO COAST TUESDAY.
MARINE
NORTHERLY WINDS HAVE ENTERED A STRENGTHENING TREND. NEAR
GALE TO GALE CONDITIONS WILL DEVELOP OVER PORTIONS OF THE WATERS
TUESDAY, MAINLY OVER THE OUTERS TUESDAY. THE NORTHERLY WINDS WILL
STRENGTHEN THROUGH WEDNESDAY. THOUGH WINDS WILL BE LIGHTER, SHORT
PERIOD AND OCCASIONALLY LARGE SEAS AROUND 9 TO 11 FEET WILL ENTER
THE INNER WATERS AROUND AND NORTH OF CAPE MENDOCINO TUESDAY THROUGH
THURSDAY MORNING. THEREAFTER, SEAS TREND LOWER AFTER THE STRONGER
NORTHERLIES LIKELY PULL FARTHER OFFSHORE.
FIRE WEATHER
AN ONGOING HEAT WAVE HAS HELPED RAPIDLY DRY FUELS.
INTERIOR HIGH TEMPERATURES HAVE BEEN REACHING NEAR 100 WITH RH
GENERALLY BETWEEN 15 AND 25 PERCENT. OVERNIGHT RH RECOVERY HAS ALSO
BEEN POOR WITH THERMAL BELTS WITH MID AND UPPER ELEVATION NIGHTTIME
RH ONLY AROUND 50 PERCENT. ERC HAS RAPIDLY INCREASED ACROSS THE
BOARD WITH MOST RAWS ALREADY REACHING NEAR THE 90TH PERCENTILE, EVEN
CLOSE TO SHORE. THAT SAID, THE GENERAL LACK OF WIND WILL CONTINUE TO
SUPPRESS THE RISK OF ANY FAST MOVING FIRES. HOT AND DRY CONDITIONS
WILL WEAKEN BEGINNING WEDNESDAY.
THE PATTERN LATE WEEK IS COMING MORE INTO FOCUS. SOME LONGER RANGE
HIGH RESOLUTION MODELS SHOW A MORE WELL FORMED THOUGH WEAK MOISTURE
PLUME MOVING UP THE SACRAMENTO VALLEY LATE WEEK. COMBINED WITH THE
THE PASSING UPPER LEVEL TROUGH, SUCH A SETUP IS LIKELY TO CREATE
THUNDERSTORMS OVER HIGH TERRAIN THURSDAY AND FRIDAY AFTERNOONS AND
EVENINGS. THE GREATEST POTENTIAL WILL BE IN NE TRINITY COUNTY (20%
CHANCE) WITH LOWER CHANCES (10%) AROUND THE YOLLA BOLLYS. ANY STORMS
THAT FORM WILL BE MOSTLY DRY. GIVEN THE PRECEDING HEAT WAVE, ANY
LIGHTNING IS LIKELY TO BE EFFICIENT WITH POSSIBLE NEW FIRE STARTS.
COASTAL FLOODING
ANOTHER HIGH ASTRONOMICAL TIDE IS PREDICTED
JUST AT 1:15 AM, WEDNESDAY, JUNE 17 FOR NORTHWEST CALIFORNIA.
HIGH TIDES HAVE BEEN REACHING 9.1 TO 9.3 FT. TIDES WILL TREND
LOWER STARTING WEDNESDAY. HIGH TIDES WILL CAUSE MINOR COASTAL
FLOODING ROUND HUMBOLDT BAY, INCLUDING KING SALMON AND LOW- LYING
ROADS NEAR ARCATA BOTTOMS.
EKA WATCHES/WARNINGS/ADVISORIES
CA...
HEAT ADVISORY UNTIL 10 PM PDT TUESDAY FOR CAZ102-105-108-
111-114-116-117.
COASTAL FLOOD ADVISORY UNTIL 2 AM PDT TUESDAY FOR CAZ103.
COASTAL FLOOD ADVISORY FROM 11 PM TUESDAY TO 3 AM PDT
WEDNESDAY FOR CAZ103.
NORTHWEST CALIFORNIA COASTAL WATERS...
COASTAL FLOOD ADVISORY UNTIL 2 AM PDT TUESDAY FOR PZZ415.
COASTAL FLOOD ADVISORY FROM 11 PM TUESDAY TO 3 AM PDT
WEDNESDAY FOR PZZ415.
SMALL CRAFT ADVISORY FROM NOON TUESDAY TO 3 AM PDT
WEDNESDAY FOR PZZ450.
SMALL CRAFT ADVISORY UNTIL 8 AM PDT TUESDAY FOR PZZ470.
GALE WARNING FROM 8 AM TUESDAY TO 9 AM PDT WEDNESDAY FOR
PZZ470.
SMALL CRAFT ADVISORY FROM 3 AM TUESDAY TO 9 AM PDT
WEDNESDAY 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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