Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 292253
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
353 PM PDT MON JUN 29 2015

.SYNOPSIS...VERY HOT AFTERNOON HIGH TEMPERATURES ACROSS INTERIOR
NORTHWEST CALIFORNIA WILL PERSIST THROUGH THE WORK WEEK. LATE
NIGHT AND MORNING COASTAL CLOUDINESS WILL GIVE WAY TO AFTERNOON
SUNSHINE.

&&

.DISCUSSION...AN UPPER RIDGE BUILDING WESTWARD FROM THE GREAT
BASIN WILL BRING HOT CONDITIONS TO THE INTERIOR VALLEYS OF NW
CALIFORNIA THROUGH THE WORK WEEK. MODELS ARE INDICATING A SMALL
SLUG OF MOISTURE MOVING TOWARD THE YOLLA BOLLYS FOR TUESDAY AND
WEDNESDAY WHICH MAY HAVE A SHOT AT GENERATING AN ISOLATED
THUNDERSTORM. THERE IS WEAK FORCING, BUT I DID NOT WANT TO IGNORE
THE POTENTIAL. OTHERWISE THERE WILL BE LIMITED CONVECTIVE
POTENTIAL THROUGH WEDNESDAY ACROSS NW CALIFORNIA. AT THE COAST, A
CHANCE OF FOG AND DRIZZLE WILL CONTINUE THE NEXT COUPLE OF
MORNINGS FOLLOWED BY PARTIAL AFTERNOON CLEARING. BFG

A BROAD SURGE OF MOISTURE IS FORECAST TO MOVE NORTH-NORTHWEST
OVER NORTHWEST CALIFORNIA BEGINNING ON THURSDAY AND PERSIST INTO
THE WEEKEND. THE GFS IS MUCH MORE AGGRESSIVE WITH THE MOISTURE
RETURN AND THUS THE LEVELS OF INSTABILITY AS COMPARED TO THE
ECMWF. HOWEVER THE WEATHER PATTERN INDICATED IN BOTH THE GFS AND
ECMWF IS TYPICAL FOR THUNDERSTORMS TO FORM OVER THE INTERIOR
MOUNTAINS ONCE MOISTURE IS SUFFICIENT. WITH THAT IN MIND, A SLIGHT
CHANCE FOR THUNDERSTORMS HAS BEEN CONTINUED ACROSS MUCH OF
INTERIOR NORTHWEST CALIFORNIA THURSDAY THROUGH SUNDAY, INCLUDING
THE OVERNIGHT PERIODS. THERE IS A GOOD CHANCE THAT ONE OR TWO OF
THESE DAYS MAY SEE VERY LITTLE THUNDERSTORM ACTIVITY AT ALL, BUT
CONFIDENCE IS NOT HIGH ENOUGH TO PINPOINT WHICH DAY WILL BE MOST
ACTIVE AT THIS TIME. FOR NOW, A BROAD BRUSH SLIGHT CHANCE SEEMS
MOST APPROPRIATE. LOW PRESSURE LINGERING OFF THE SOUTHERN CALIFORNIA
COAST LATE IN THE WEEK SHOULD DISRUPT THE MARINE LAYER ENOUGH TO
ALLOW MORE CLEARING ALONG THE NW CAL COAST WITH NO MORNING FOG
EXPECTED. RPA/BFG

&&

.AVIATION...POCKETS OF STRATUS REMAINED STUBBORNLY INUNDATED ALONG
PARTS OF THE COAST TODAY. FURTHER SCATTERING WILL BE POSSIBLE IN
THE LATE AFTERNOON HOWEVER SOME LOCATIONS MAY NOT SEE ANY
IMPROVEMENT BY THIS EVENING. STRATUS SHOULD FILL BACK IN MOST OF
THE NORTHWEST CALIFORNIA COAST THIS EVENING. WEAK RIDING BEHIND
THE EXITING TROUGH WILL HELP LOWER CEILINGS OVERNIGHT YET
VISIBILITIES SHOULD BE A LITTLE HIGHER THAN OBSERVED LAST NIGHT.
CONDITIONS WILL LIKELY BE VARIABLE OVERNIGHT BUT THE OVERALL TREND
WILL BE FOR COASTAL AIRFIELDS TO RANGE FROM MVFR TO IFR WITH VFR
TO PREVAIL INLAND. /KML

&&

.MARINE...LIGHT TO MODERATE NORTHERLY WINDS DEVELOPED TODAY AS A
WEAK SURFACE LOW SHIFTED TO THE NORTHWEST. WINDS WILL INCREASE
THROUGH THIS AFTERNOON INTO TUESDAY AS HIGH PRESSURE BUILDS TOWARD
THE COAST AND THE THERMAL TROUGH INTENSIFIES OVER COASTAL
CALIFORNIA. NORTH WINDS WILL INITIALLY BE STRONGEST SOUTH OF CAPE
MENDOCINO TONIGHT WHERE A SMALL CRAFT ADVISORY FOR BOTH WINDS AND
SEAS WILL BEGIN. ON TUESDAY THE THERMAL TROUGH WILL SHIFT WESTWARD
TIGHTENING THE GRADIENT ACROSS THE OUTER WATERS RESULTING IN GALE
FORCE WIND GUSTS. THE NORTHERN OUTER WATERS COULD SEE GUSTS NEAR
40 KNOTS TUESDAY THROUGH EARLY WEDNESDAY. THE GALE WATCH REMAINS
IN EFFECT FOR TUESDAY BUT MAY NEED TO BE UPGRADED TO A WARNING
WITH THE OVERNIGHT UPDATE SO LONG THE FORECAST REMAINS ON TRACK.
THE GRADIENT WILL RELAX A BIT LATER THIS WEEK YET REMAIN STRONG
ENOUGH TO MAINTAIN MODERATE TO STRONG NORTHERLY WINDS THROUGH THE
EARLY HALF OF THE WEEKEND. STEEP WAVES WILL DEVELOP IN RESPONSE TO
THE INCREASING WINDS TONIGHT AND BUILD THROUGH TUESDAY. THE
LARGEST SEAS WILL BE OFFSHORE ON TUESDAY AROUND 10 TO 12 FT AND
THEN EASE LATER IN THE WEEK. DESPITE THE SEA STATE BEING DOMINATED
BY LOCALLY GENERATED WAVES A PERSISTING SOUTH SWELL WILL CONTINUE
TO PROPAGATE THE COASTAL WATERS WITH THE GREATEST IMPACT TO SOUTH
FACING BEACHES WITH SLIGHTLY LARGER SETS OF WAVES. /KML

&&

.FIRE WEATHER...DRY AND HOT CONDITIONS ARE EXPECTED THIS WEEK WITH
AFTERNOON MINIMUM RH VALUES IN THE TEENS ACROSS MUCH OF THE INTERIOR
TUESDAY THROUGH THURSDAY. RH RECOVERIES OVERNIGHT WILL BE FAIRLY
GOOD CONSIDERING THE WARM TEMPERATURES. WEDNESDAY NIGHT LOOKS TO
HAVE THE POOREST RECOVERIES WITH RH REACHING ONLY 30-40 PERCENT
IN THE MOUNTAINS. WINDS WILL REMAIN LIGHT AND DRIVEN MOSTLY BY
TERRAIN AND DIURNAL EFFECTS. THUS NO SIGNIFICANT FIRE WEATHER
CONCERNS ARE EXPECTED FROM THE HEAT AND LOW RH. THERE IS AN
OUTSIDE SHOT AT A THUNDERSTORM OR TWO OVER THE YOLLA BOLLYS
TUESDAY AND WEDNESDAY AFTERNOON AS A WEAK PULSE OF MOISTURE SLIDES
UP THE INTERIOR VALLEY. AT MINIMUM THIS WILL CREATE SOME CLOUD
COVER OVER TRINITY COUNTY WHICH COULD CAUSE COOLER DAY TIME HIGHS.
WE WILL NEED TO WAIT AND SEE HOW THIS PANS OUT TUESDAY AFTERNOON
TO GET AN IDEA WHAT WILL HAPPEN ON WEDNESDAY.

ANOTHER CHANCE FOR THUNDERSTORMS WILL RETURN THURSDAY THROUGH SUNDAY
AS MOISTURE STREAMS NORTH ON THE WEST SIDE OF AN AMPLIFIED WESTERN
U.S. RIDGE. THERE REMAINS CONSIDERABLE UNCERTAINTY AS TO HOW MUCH
CONVECTIVE ACTIVITY WILL ACTUALLY DEVELOP, BUT THE PATTERN IS
TYPICAL FOR THUNDERSTORMS OVER THE INTERIOR MOUNTAINS. MODEL
TRENDS WILL HAVE TO BE MONITORED CLOSELY. RPA/BFG

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON
     FOR PZZ470.

     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 5 PM PDT TUESDAY
     FOR PZZ455.

     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 5 PM PDT
     WEDNESDAY FOR PZZ475.

&&

$$

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