892  
FXUS66 KEKA 012230  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
330 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.  
 

 
   
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 THIS EVENING FOR PZZ450.  
 
SMALL CRAFT ADVISORY UNTIL 9 PM PDT FRIDAY FOR PZZ470.  
 
HAZARDOUS SEAS WARNING UNTIL 9 PM PDT THIS EVENING FOR PZZ470.  
 
SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY FOR PZZ475.  
 

 
 

 
 
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