231  
FXUS66 KEKA 271228  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
428 AM PST FRI FEB 27 2015  
   
SYNOPSIS
 
A STORM SYSTEM APPROACHING FROM THE NORTH WILL BRING  
RAIN SHOWERS...COOLER TEMPERATURES AND SOME MOUNTAIN SNOW TODAY  
THROUGH SATURDAY. DRY CONDITIONS ARE EXPECTED SUNDAY FOLLOWED BY  
ANOTHER STORM SYSTEM WITH RAIN SHOWERS MONDAY AND TUESDAY.  
 

 
   
DISCUSSION
 
WATER VAPOR AND RADAR SHOWS A WEAK FRONTAL BOUNDARY  
PUSHING DOWN FROM THE NORTH OVER THE AREA. THIS HAS BROUGHT  
RAINFALL TO HUMBOLDT AND DEL NORTE COUNTIES WITH AMOUNTS RANGING  
FROM A FEW HUNDREDTHS IN SOUTHERN HUMBOLDT TO OVER A HALF INCH  
IN THE NORTH. SNOW LEVELS WITH THIS INITIAL BAND LOOK TO HAVE  
BEEN AROUND 5000 TO 5500 FT. TODAY THE FRONTAL BOUNDARY PUSHES  
SOUTH ACROSS THE AREA USHERING IN COOLER AIR AND SOME ADDITIONAL  
RAINFALL. SURFACE OBSERVATIONS IN OREGON HAVE STARTED TO COOL  
ALREADY. MODELS STRUGGLE WITH THE AMOUNTS OF PRECIP AND VARY QUITE  
A BIT SO CONFIDENCE IS LOW ON THE RAIN AND SNOW AMOUNTS. GENERALLY  
WENT WITH THE NAM AS IT SEEMED TO BE HANDLING THE SMALL SCALE  
FEATURES BETTER.  
 
TONIGHT COOLER AIR FILTERS IN AS THE TROUGH MOVES OVERHEAD.  
MODELS ARE SHOWING SOME INSTABILITY BEHIND THIS FRONT SO ADDED  
SOME THUNDERSTORMS TO DEL NORTE COUNTY LATE THIS AFTERNOON AND  
EVENING. PRECIP AMOUNTS CONTINUE TO VARY FROM MODEL TO MODEL...BUT  
ARE GENERALLY LIGHT TONIGHT. SNOW LEVELS LOOK TO BE AROUND 3500 TO  
4000 FT. SNOWFALL AMOUNTS LOOK TO BE LESS THAN 2 INCHES. THESE MAY  
BE LOCALLY HIGHER IN HEAVIER SHOWERS. SATURDAY MORNING  
TEMPERATURES WILL BE A BIT CHILLY...BUT THERE SHOULD BE ENOUGH  
CLOUDS AND MIXING TO KEEP THEM FROM DROPPING PARTICULARLY LOW.  
 
SATURDAY AFTERNOON THE BACKSIDE OF THE UPPER LEVEL SLOWLY DROPS  
ACROSS THE AREA. THIS IS EXPECTED TO BRING A SOME ADDITIONAL RAIN  
AND SNOW WITH SNOW LEVELS AROUND 3500 FT. THIS LOOKS TO BRING  
ANOTHER SLIGHT CHANCE FOR THUNDERSTORMS SO HAVE EXPANDED THE  
COVERAGE OVER THE AREA ON SATURDAY AFTERNOON.  
 
LATE SATURDAY AFTERNOON THE DRIER AIR AND OFFSHORE FLOW STARTS TO  
PUSH INTO THE AREA. THIS WILL MAKE SUNDAY MORNING ONE OF THE  
CHILLIEST STARTS TO THE DAY IN A WHILE. THIS ALSO COINCIDES WITH  
THE BEGINNING OF OUR LOCALLY DEFINED GROWING SEASON IN THE COASTAL  
AND MENDOCINO ZONES. SO THIS WILL LIKELY NEED A FROST OR FREEZEWARNING...BUT  
WILL HOLD OFF ON ISSUING IT JUST YET.  
 
MONDAY INTO TUESDAY ANOTHER WEAK SYSTEM BRINGS SOME ADDITIONAL  
LIGHT RAIN TO THE AREA. THE GFS IS NEARLY DRY NOW...HOWEVER THE  
ECMWF REMAINS A BIT WETTER...SO LEFT THE FORECAST IN THE CHANCE  
CATEGORY. WEDNESDAY THROUGH THURSDAY HIGH PRESSURE BUILDS BACK  
INTO THE AREA. FRIDAY MODELS ARE HINTING AT ANOTHER SYSTEM  
BRINGING SOME VERY LIGHT RAIN...BUT CONFIDENCE IS LOW AT THIS  
POINT. MKK  
 

 
   
AVIATION
 
CONDITIONS WILL CONTINUE TO VARY THIS MORNING AS  
RAINFALL PERIODICALLY LOWERS CEILINGS AND VISIBILITIES ACROSS PARTS  
OF NORTHWEST CALIFORNIA. EXPECT CONDITIONS TO IMPROVE INTO THE  
AFTERNOON AND EARLY EVENING AS A LOW PRESSURE SYSTEM SHIFTS OVER  
NORTHERN CALIFORNIA BRINGING A COLDER AND DRIER AIRMASS TO THE  
REGION. RAIN ON THE LEADING EDGE OF THIS SYSTEM WILL SHIFT FROM  
NORTH TO SOUTH THROUGH THE DAY AND SHOULD CEASE NEAR THE END OF THE  
TAF PERIOD. KML  
 

 
   
MARINE.
 
NORTHERLY CONDITIONS WILL PERSIST TODAY AS THE PRESSURE  
GRADIENT REMAINS TIGHT ACROSS THE COASTAL WATERS. SEAS WILL BUILD  
TODAY AS A NORTHWESTERLY WAVE SYSTEM PROPAGATES THE WATERS THROUGH  
THIS AFTERNOON. CONDITIONS WILL CONTINUE TO INCREASE ON SATURDAY AS  
A LOW PRESSURE SYSTEM TRAVELS SOUTHWARD ALONG THE WEST COAST WHILE  
PUSHING AGAINST THE RIDGE OF HIGH PRESSURE OFFSHORE. THIS WILL CAUSE  
THE GRADIENT TO TIGHTEN FURTHER BRINGING SOME GALE FORCE GUSTS TO  
THE OUTER WATERS SATURDAY INTO THE EVENING. FOR NOW I HELD OFF ON  
ISSUING ANY GALE WATCHES OR WARNINGS DUE TO THE MARGINALITY OF  
CONDITIONS. OTHERWISE SMALL CRAFT ADVISORIES CONTINUE FOR THE OUTER  
WATERS THROUGH SUNDAY MORNING WITH A NEWLY ADDED ADVISORY FOR THE  
SOUTHERN INNER WATERS FOR STEEP SEAS AND GUSTY WINDS THIS AFTERNOON.  
THERE IS A POTENTIAL THAT ADVISORIES MAY NEED TO BE EXTENDED INTO  
SUNDAY AS CONDITIONS ARE EXPECTED TO REMAIN ELEVATED THROUGH EARLY  
NEXT WEEK. FOR NOW, WE WILL WAIT FOR NEW MODEL INFORMATION TO SEE IF  
WINDS AND SEAS SHOULD BRIEFLY FALL BELOW CRITERIA LEVELS ON SUNDAY.  
KML  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
NORTHWEST CALIFORNIA COASTAL WATERS...  
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 AM PST SUNDAY  
FOR PZZ470.  
 
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 PM PST THIS  
EVENING FOR PZZ455.  
 
SMALL CRAFT ADVISORY UNTIL 9 AM PST SUNDAY FOR PZZ475.  
 

 
 

 
 
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