351  
FXUS66 KEKA 202226  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
326 PM PDT SAT SEP 20 2014  
   
SYNOPSIS
 
HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS  
AND SEASONABLE TEMPERATURES TO NORTHWEST CALIFORNIA THIS WEEKEND.  
EXPECT LOW CLOUDS AND FOG ALONG THE COAST DURING THE NIGHT AND  
MORNING WITH PARTIAL CLEARING IN THE AFTERNOON. A TROUGH WILL  
BEGIN TO MOVE OVER THE WEST COAST EARLY NEXT WEEK...BRINGING  
COOLER TEMPERATURES AND WIDESPREAD RAIN BY THE MIDDLE OF THE WEEK.  
 

 
   
SHORT TERM
 
2130Z VISIBLE SATELLITE SHOWS CLOUDS ALONG MOST OF  
THE IMMEDIATE COAST AND MOSTLY SUNNY SKIES ELSEWHERE. THE CLOUDS  
WILL THICKEN ALONG THE IMMEDIATE COAST EARLY THIS EVENING AND  
OVERNIGHT. VISIBILITIES SHOULD DROP IN THESE LOCATIONS AS FOG  
DEVELOPS. EXPECT PARTIAL CLEARING BY SUNDAY AFTERNOON. OTHERWISE,  
HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS AND SEASONABLE  
TEMPERATURES TO NORTHWEST CALIFORNIA THROUGH SUNDAY. A PACIFIC  
TROUGH WILL BEGIN TO MOVE OVER THE WEST COAST ON MONDAY, BRINGING  
COOLER TEMPERATURES AND SOME HIGH CLOUDS.  
   
LONG TERM (TUE MORNING-SATURDAY)
 
MODELS CONTINUE TO BE IN  
OVERALL AGREEMENT BUT ONLY NOW THROUGH WEDNESDAY AFTERNOON AS THE  
NEXT SIGNIFICANT TROUGH APPROACHES AND IMPACTS THE COAST. EC IS A  
LITTLE FASTER WITH TIMING OF FRONT BRINGING IT INTO CEC BY TUE  
EVENING WHILE GFS BRINGS IT IN A LITTLE BEFORE SUNRISE WED  
MORNING. I WILL LEAN TOWARD TIMING OF GFS WITH FRONTAL PASSAGE  
THROUGH ALL OF TRINITY AND MENDO COUNTY BY WED EVENING. PWATS  
AHEAD OF FRONT ARE BETWEEN 1-1.5 INCHES AND THE INTEGRATED WATER  
VAPOR TRANSPORT (IVT) WHICH COMBINES THE MOISTURE AND WIND IS ALSO  
HIGH WITH A RETURN INTERVAL OF 10 YEARS NEAR CEC AND 5 YEARS DOWN  
NEAR UKIAH. WITH GOOD MOISTURE AND DYNAMICS COULD SEE BRIEF  
PERIODS OF HEAVY RAIN WITH THE FRONT. WITH THE INCREASING  
SOUTHERLY WINDS AHEAD OF THE FRONT, SHOULD SEE SOME GUSTY WINDS  
ESPECIALLY OVER THE HIGHER RIDGES DURING THE DAY WED. BEHIND  
FRONT, MODELS ARE DIFFERING WITH WHAT TO DO WITH THE ASSOCIATED  
TROUGH. GFS SWINGS IT THROUGH ON THURSDAY WITH RIDGE BUILDING OVER  
THE WEEKEND WITH A RETURN TO DRY WEATHER. EC IS SLOWER AND DEEPER  
WITH THE BROAD TROUGH STILL OVER THE AREA THROUGH THE WEEKEND  
WHICH COULD KEEP SHOWERS GOING. WENT WITH WPC'S THINKING WHICH  
SWINGS THE TROUGH THROUGH LIKE THE GFS THOUGH A LITTLE SLOWER.  
WILL HAVE TO WATCH THE LARGE AREA OF HIGH PRESSURE IN THE EASTERN  
US TO SEE IF IT SLOWS DOWN THE TROUGH OR CUTS IT OFF AS IT COMES  
INTO THE WEST COAST. WPC'S STILL FORECASTING ABOUT 2.5 INCHES OF  
RAIN NEAR CEC FOR THE ENTIRE STORM SYSTEM AND AT LEAST 0.50 INCHES  
EVERYWHERE ELSE. COLDER AIR WITH THE TROUGH AS 850MB TEMPS DROP  
DOWN TO ABOUT 5C AND VERY HIGHEST PEAKS COULD GET A DUSTING OF  
SNOW. LAPSE RATES DO NOT LOOK STEEP ENOUGH FOR ANY THUNDERSTORMS  
BUT WILL STILL NEED TO KEEP AN EYE ON IT. DEAN  
 

 
   
AVIATION
 
2130Z VISIBLE SATELLITE SHOWS CLOUDS ALONG MOST OF  
THE IMMEDIATE COAST, BRINGING LIFR, AND MOSTLY SUNNY SKIES WITH  
VFR ELSEWHERE. ALONG THE IMMEDIATE COAST...EXPECT THE CLOUDS TO  
THICKEN EARLY THIS EVENING AND OVERNIGHT. VISIBILITIES ARE  
EXPECTED TO DROP IN MOST LOCATIONS AS FOG DEVELOPS.  
INLAND...EXPECT VFR TO PREVAIL, EXCEPT FOR SOUTHERN MENDOCINO  
COUNTY WHERE VALLEY CLOUDS/FOG MAY DEVELOP LATE.  
 

 
   
MARINE
 
THE SMALL CRAFT ADVISORY FOR THE NORTHERN OUTER WATERS  
HAS BEEN ALLOWED TO EXPIRE THIS AFTERNOON AS WINDS AND SEAS HAVE  
FALLEN BELOW ADVISORY LEVELS.  
 
ELONGATED LOW PRESSURE OFF THE OR/CA BORDER HAS BEEN MAINTAINING  
FRESH SOUTHERLY WINDS AROUND CAPE MENDOCINO TODAY. A LATE MORNING  
ASCAT PASS CONFIRMED THE EARLY MORNING FORECAST WITH 20 KT WINDS  
AROUND THE CAPE. WHILE AT BUOY 22 THE GUSTS HAVE PROVEN TO BE WELL  
FORECAST AT AROUND 25 KT. AS THIS LOW LIFTS TO THE NW AND FILLS  
OVER THE NEXT SEVERAL HOURS, THE WINDS WILL COME DOWN WHICH IN  
TURN WILL ALLOW FOR THE STEEP SOUTHERLY WAVES TO SUBSIDE.  
OTHERWISE, A NW SWELL REMAINS THE MAIN HEIGHT PLAYER IN THE SEA  
STATE, RUNNING AROUND 7 FT AT 12 SECONDS THIS AFTERNOON. THIS  
SWELL WILL SLOWLY SUBSIDE THROUGH SUNDAY. SUNDAY AND MONDAY SHOULD  
HAVE GENERALLY LIGHT TO MODERATE WINDS AND SEAS AROUND 3 TO 4 FT  
AT 10 SECONDS.  
 
TUESDAY WILL BE A TRANSITION DAY AS AN APPROACHING FRONT BRINGS  
WINDS TO THE SOUTH AND INCREASES OVERNIGHT. BY LATE TUE INTO WED,  
EXPECT WINDS INTO THE 15 TO 25 KT RANGE WITH RESULTANT STEEP  
SOUTHERLY WAVES. AT THE SAME TIME A POST FRONTAL WESTERLY SWELL,  
WHICH IS OUT RUNNING THE SPEED OF THE FRONT, WILL BEGIN TO BUILD  
INTO THE WATERS, PEAKING OUT AROUND 12 FT AT 15 SECONDS OVERNIGHT  
WED INTO THU. WHILE SMALL CRAFT ADVISORIES WILL BE NEEDED BY  
MIDWEEK FOR ALL WATERS, WE'LL BE WATCHING FOR THE POSSIBILITY OF  
HOISTING A HAZARDOUS SEAS WARNING FOR THE NORTHERN OUTER WATERS.  
CONDITIONS WILL SUBSIDE AS QUICKLY AS THEY BUILT ON THU INTO FRI.  
MODEL SHOW NW CAL SLIDING UNDER A WEAK PRESSURE GRADIENT WHICH  
WILL ALLOW FOR EASING WINDS AND SUBSIDING STEEP WAVES. TIMING  
REMAINS A LITTLE FUZZY WITH THE ONSET AND SUBSIDING OF THE WORST  
CONDITIONS, BUT REGARDLESS MIDWEEK IS LOOKING NOT SO NICE TO BE  
OUT TO SEA. KEEP AN EYE ON THE FORECAST AND THIS DISCUSSION FOR  
THE LATEST INFO. BFG  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
 
NORTHWEST CALIFORNIA COASTAL WATERS...  
 
SMALL CRAFT ADVISORY FOR PZZ470.  
 

 
 

 
 
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