Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 020458 AAA
AFDEKA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE EUREKA CA
958 PM PDT WED JUL 1 2015

.SYNOPSIS...VERY HOT CONDITIONS WILL CONTINUE ACROSS THE INTERIOR
VALLEYS THROUGH THURSDAY. SEASONAL CONDITIONS WILL PERSIST ALONG
THE COASTAL PLAINS. MONSOONAL MOISTURE WILL BRING A CHANCE OF
THUNDERSTORMS TO THE MOUNTAINS THURSDAY AND OVER THE WEEKEND.

&&

.UPDATE...WATER VAPOR IMAGERY SHOWERS A SHORTWAVE OVER THE
NEVADA/CALIFORNIA BORDER. MODELS SHOW THIS WAVE MOVING TOWARDS
NORTHWEST CA LATE TONIGHT INTO THURSDAY MORNING. THE GFS BRINGS
SOME LIGHT SHOWERS TO SOUTHERN MENDOCINO COUNTY SO HAVE A SLIGHT
CHANCE OF SHOWERS TO THE FORECAST. AMOUNTS WILL BE LIGHT...UP TO A
TENTH OF AN INCH AT MOST. THERE IS AN OUTSIDE CHANCE OF A
SOME LIGHTNING WITH THIS AS WELL...BUT AT THIS POINT THE THREAT
LOOKS TOO SMALL TO ADD TO THE FORECAST. THIS WILL NEED TO BE
WATCHED. MKK

&&

.PREV DISCUSSION......ISSUED AT 330 PM PDT...

SHORT TERM (TONIGHT THRU SATURDAY NIGHT)...VISIBLE SATELLITE
IMAGERY SHOWED STRATUS LINGERING ALONG PARTS OF THE COAST AS OF
21Z...WITH SOME HIGH CLOUDS ASSOCIATED WITH MONSOONAL MOISTURE
DRIFTING NORTHWARD OVER SOUTHERN MENDOCINO COUNTY. STRATUS SHOULD
PULL BACK TO AT LEAST THE IMMEDIATE COAST THIS
AFTERNOON/EVENING...EXPANDING ALONG THE COAST AND INTO ADJACENT
RIVER VALLEYS OVERNIGHT.

THE MAIN STORY OVER THE NEXT 24 HOURS CONTINUES TO BE A STRONG UPPER
RIDGE BUILDING WESTWARD FROM THE GREAT BASIN BRINGING VERY HOT
CONDITIONS TO THE INTERIOR VALLEYS OF NORTHWEST CALIFORNIA. MANY
LOCATIONS WERE ALREADY IN THE UPPER 90S AND WELL INTO THE 100S F
AS OF 21Z. LOWS TONIGHT WILL RANGE FROM THE MIDDLE 60S TO LOW 70S F.
AS A RESULT...HEAT ADVISORIES FOR INLAND VALLEY LOCATIONS REMAIN
IN EFFECT THROUGH LATE TONIGHT. GOING INTO THURSDAY...AN INCREASE
IN CLOUD COVER AND LOW LEVEL MOISTURE SHOULD KEEP TEMPERATURES
ACROSS THE SOUTHERN PORTION OF THE AREA SLIGHTLY COOLER THAN
TODAY. HIGH TEMPERATURES ACROSS TRINITY AND INTERIOR LOCATIONS OF
HUMBOLDT AND DEL NORTE COUNTY SHOULD REMAIN SIMILAR TO TODAY.
THUS...HAVE OPTED TO CONTINUE THE HEAT ADVISORY FOR THESE
LOCATIONS FROM THURSDAY AFTERNOON THROUGH LATE THURSDAY NIGHT.

AN UPPER LOW OFF THE SW CALIFORNIA COAST AND THE AFOREMENTIONED HIGH
PRESSURE BUILDING OVER THE INTERIOR WEST WILL WORK IN TANDEM TO
TRANSPORT MONSOONAL MOISTURE AND INSTABILITY OVER NW CALIFORNIA
INTO THE WEEKEND. THIS WILL LEAD TO AN INCREASE IN CLOUD COVER AND
SHOWER AND THUNDERSTORM CHANCES...STARTING THURSDAY AFTERNOON AND
CONTINUING INTO THE WEEKEND AS THE UPPER LOW DRIFTS NORTHEASTWARD
TOWARD THE CENTRAL CALIFORNIA COAST...PUTTING THE AREA UNDER
SOUTHEAST FLOW. PRECIPITABLE WATER VALUES START OUT NEAR 0.75
INCHES OF H2O AND INCREASE TOWARDS 1.75 INCHES OF H2O BY
SATURDAY...NEARLY 5 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME
OF YEAR. BOTH THE GFS AND NAM SHOW PRECIPITATION DRIFTING WEST
TOWARD THE COAST THURSDAY NIGHT INTO FRIDAY. LOOKING AT
INSTABILITY PARAMETERS...THINK THAT IF ANYTHING DEVELOPS
OVERNIGHT...IT WOULD MOST LIKELY BE SHOWERS WITH A COUPLE ISOLATED
LIGHTNING STRIKES POSSIBLE. THIS WILL NEED TO BE MONITORED FOR ANY
FIRE WX CONCERNS. QUESTIONS STILL REMAIN IN THE TIMING OF WAVES
OF ENERGY ROTATING THROUGH THE AREA ASSOCIATED WITH THE TIMING OF
THE BEST INSTABILITY. AT THIS POINT...THE BEST CHANCES FOR
THUNDERSTORMS LOOK TO BE OVER THE WEEKEND...HIGHEST OVER THE
EASTERN MOUNTAINS.

COASTAL LOCATIONS WILL CONTINUE TO SEE LOW CLOUDS/FOG MOST NIGHTS
AND MORNINGS WITH SEASONABLE TEMPERATURES. AFTER THURSDAY...INTERIOR
TEMPERATURES WILL COOL SLIGHTLY INTO THE WEEKEND AS THE UPPER LOW
APPROACHES THE AREA DECREASING HEIGHTS ALOFT AND INCREASING CLOUD
COVER. STP

LONG TERM (SUNDAY THRU TUESDAY)...LONG WAVE RIDGING OVER THE
WESTERN UNITED STATES WILL DOMINATE THE UPPER WEATHER PATTERN
THROUGH THE EXTENDED FORECAST. LOW PRESSURE SOUTHWEST OF CALIFORNIA
WILL SHIFT NORTHWARD CAUSING 500 MB HEIGHTS TO FALL AND DEVELOP A
SADDLE OVER THE PACIFIC NORTHWEST EARLY NEXT WEEK. THIS WILL CUT OFF
THE FEED TO MONSOONAL MOISTURE CAUSING PWATS OVER THE CWA TO DROP
UNDER ONE INCH STARTING MONDAY. ADDITIONALLY, HOT TEMPERATURES WILL
GRADUALLY DECREASE TO NEAR NORMAL BY THE MIDDLE OF NEXT WEEK. ON
SUNDAY THERE REMAINS A SLIGHT CHANCE FOR THUNDERSTORMS FOR THE
EASTERN REACHES OF THE CWA AS MOISTURE AND INSTABILITY ARE READILY
AVAILABLE BUT THE TRIGGER STILL LOOKS WEAK AT THIS TIME. MODELS SHOW
POTENTIAL FOR AFTERNOON CONVECTION JUST NEAR OUR CWA BORDER INTO
SISKIYOU COUNTY EARLY NEXT WEEK, HOWEVER, THERE IS TOO MUCH
UNCERTAINTY AT THIS TIME AND MAINTAINED GHOST POPS. /KML

AVIATION...OVERNIGHT/MORNING COASTAL STRATUS CLOUDS AGAIN COVERED
MUCH OF THE REDWOOD COAST AND LOCAL RIVER VALLEYS...ALTHOUGH NOT
QUITE AS DEEP AS THE PREVIOUS DAY OR TWO. AREAS OF STRATUS WILL
MOSTLY CLEAR TO THE IMMEDIATE COAST BUT SOME POCKETS OF STRATUS MAY
MEANDER ONTO THE COAST PRODUCING SCT OCNL BKN CIGS. CLOUDS WILL
SURELY MOVE BACK TOWARDS THE COASTAL INLAND AND RIVER VALLEYS BY
LATE AFTERNOON AND EARLY EVENING. SOME HIGH CLOUDS CAN BE EXPECTED
OVER THE INTERIOR. TA

MARINE...LIGHT TO FRESH WINDS WILL CONTINUE OVER THE NEXT FEW DAYS
AS THE PERSISTING RIDGE OFFSHORE AND THERMAL TROUGH INLAND MAINTAIN
A TIGHTENED PRESSURE GRADIENT ACROSS THE COASTAL WATERS. THIS
WEEKEND A SURFACE LOW WILL TRAVEL UP THE COAST AND BUST UP THE
GRADIENT WHICH WILL ALLOW THE WINDS TO EASE. SOUTHERLY FLOW WILL
DEVELOP BY SUNDAY AND PERSIST THROUGH EARLY NEXT WEEK. THIS WILL
CREATE SOUTHERLY WIND CHOP. THE WAVE ENVIRONMENT SHOULD OTHERWISE BE
DOMINATED BY SHORTER PERIOD NORTHERLY WAVES OVER THE NEXT FEW DAYS.
MEANWHILE A PERSISTING SOUTH SWELL WILL CONTINUE TO PROPAGATE THE
COASTAL WATERS THROUGH THE FORECAST PERIOD. AS OF THIS AFTERNOON,
NEARSHORE BUOY OBSERVATIONS ARE REACHING SMALL CRAFT CRITERIA NORTH
OF CAPE MENDOCINO. AS A RESULT THE HAZARDOUS SEAS WARNING AND THE
SMALL CRAFT ADVISORY FOR THE NORTHERN WATERS HAS BEEN EXTENDED
THROUGH 9 PM TONIGHT. A SMALL CRAFT ADVISORY WAS ALSO ADDED TO THE
NORTHERN OUTER WATERS AND WILL CONTINUE THROUGH FRIDAY EVENING. /KML

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     HEAT ADVISORY UNTIL 1 AM PDT THURSDAY FOR CAZ076.

     HEAT ADVISORY UNTIL 1 AM PDT FRIDAY FOR CAZ003-004.

NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 9 PM PDT FRIDAY FOR PZZ470.

     SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY FOR PZZ475.

&&

$$

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