425  
FXUS66 KEKA 241250  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
450 AM PST TUE JAN 24 2017  
   
SYNOPSIS
 
HIGH PRESSURE WILL BUILD TOWARD THE COAST TODAY  
PROVIDING DRY WEATHER THROUGH MOST OF THE DAY ON WEDNESDAY. A WEAK  
FRONT WILL APPROACH THE COAST LATE ON WEDNESDAY AND MAY PRODUCE  
SOME LIGHT SHOWERS BY WEDNESDAY NIGHT. RIDGING WILL RETURN LATER  
IN THE WEEK BRINGING DRY WEATHER THROUGH THE WEEKEND.  
 

 
   
DISCUSSION
 
RADAR HAS BEEN SHOWING ISOLATED RETURNS OVER THE  
EASTERN FRINGES OF TRINITY COUNTY AS WELL AS THE EASTERN AND FAR  
SOUTHERN PORTIONS OF MENDOCINO COUNTY EARLY THIS MORNING. THE  
NAM AND HRRR LOOKED TO HAVE THE BEST HANDLE ON THE UPSLOPE/WRAP  
AROUND PRECIP. BOTH MODELS INDICATE ISOLATED SHOWERS PERSISTING  
EARLY THIS MORNING, THEN RAPIDLY DECAYING SHORTLY AFTER SUNRISE  
AS A SURFACE LOW WEST OF SFO BAY SLIDES SOUTHWARD. EXCEPT FOR  
SOME PATCHES OF FOG AND LOW CLOUDS IN THE INTERIOR VALLEYS AND  
THE RESIDUAL SHOWERS, IT IS SHAPING UP TO BE A FINE DAY WITH  
BOUNTIFUL SUNSHINE.  
 
UPPER LEVEL RIDGING OFFSHORE WILL EDGE CLOSER TO THE COAST  
TONIGHT AS AN UPPER TROUGH WEST OF 140W PUSHES EASTWARD. EXPECT  
MOSTLY CLEAR SKIES WITH COLDER OVERNIGHT TEMPERATURES. SOME FOG  
AND LOW CLOUDS WILL PROBABLY DEVELOP OVERNIGHT IN THE INTERIOR  
VALLEYS.  
 
ALL THE MODELS HAVE A WEAKENING FRONT APPROACHING THE COAST  
ON WEDNESDAY. EXPECT WE WILL SEE AN INCREASE IN AT LEAST HIGH  
LEVEL CLOUDS DURING THE DAY ON WED. THE LATEST NAM, GFS AND ECMWF  
HAVE SLOWED DOWN THE FRONT WHICH WILL MOST LIKELY STALL AND  
BECOME STATIONARY OFFSHORE BEFORE REACHING THE COAST. THE FRONT  
WILL MEANDER OFFSHORE NEAR THE COASTLINE WED NIGHT WHICH MAY BE  
THE BEST OPPORTUNITY FOR RECEIVING LIGHT RAIN. EXPECT THE BOUNDARY  
TO DISSIPATE BY EARLY THU MORNING. THE NAM AND BUFKIT PROFILES  
INDICATE THE BOUNDARY LAYER MOISTENING UP WED NIGHT, HOWEVER THE  
NAM MAY BE OVERDONE WITH THE SHALLOW PUSH OF MOIST AIR. IF WE DO  
RECEIVE ANY PRECIP, EXPECT IT TO BE FAIRLY LIGHT WITH PERHAPS A  
FEW HUNDREDTHS BY EARLY THU MORNING.  
 
UPPER LEVEL RIDGING WILL SPRING BACK UP LATER ON THU AND HOLD  
OVER THE REGION THROUGH THE WEEKEND. THE FORECAST FOR THE REST OF  
THE PERIOD IS LOOKING QUITE DRY. IT IS VERY TYPICAL FOR THE  
INTERIOR VALLEYS TO CLOUD UP AND FOG UP DURING THE NIGHT AND EARLY  
MORNING HOURS WHEN SKIES CLEAR OUT THIS TIME OF YEAR. THE AIR  
MASS DOES WARM UP OVER THE WEEKEND AND COASTAL STRATUS MAY BECOME  
MORE PROBLEMATIC. THE RIDGE SHOULD START TO FLATTEN OUT AND  
WEAKEN EARLY NEXT WEEK. THE GFS AND ECMWF BRING A FRONT TOWARD  
THE COAST ON TUE WHICH WILL BE OUR NEXT CHANCE OF RAIN.  
 

 
   
AVIATION
 
OVERNIGHT, CLEARING SKIES TOOK PLACE AS THE LOW  
CONTINUES TO MOVE SOUTH TOWARDS BAJA CALIFORNIA. THE NORTHEASTERLY  
OFFSHORE FLOW IN THE LOW LEVEL TRANSPORTED DRIER AIR FROM THE  
INTERIOR INTO NW CALIFORNIA. CRESCENT CITY AND ARCATA AIRPORTS  
REPORTED CLEAR SKIES EARLY THIS MORNING. THERE WERE STILL SOME  
LINGERING SHOWERS AND CLOUDS OVER UKIAH AREA. HOWEVER, DO EXPECT  
THE CLEARING SKIES TO REACH THEM LATER THIS MORNING. ALL  
TERMINALS SHOULD SEE CLEAR SKIES THROUGH THE DAY TODAY. HOWEVER,  
THE NEXT SYSTEM WILL BRING IN HIGH CLOUDS TO THE AREA TERMINALS  
THIS EVENING INTO THE OVERNIGHT HOURS. CONDITIONS SHOULD REMAIN  
VFR FOR ALL TERMINALS. /RCL  
 

 
   
MARINE
 
THIS MORNING, SEAS ARE SUBSIDING AS THE WESTERLY SWELL  
DISSIPATES. WITH THE LOWERING WAVE HEIGHTS, DOWNGRADED THE HAZARDOUS  
SEAS WARNING INTO SMALL CRAFT ADVISORY. THE SMALL CRAFT ADVISORY IS  
GOOD UNTIL 9 AM THIS MORNING FOR THE NORTHERN WATERS, WHILE IT IS  
GOOD UNTIL 3 PM THIS AFTERNOON FOR THE SOUTHERN WATERS. LIGHT TO  
MODERATE NORTH WINDS ARE IN STORE FOR TODAY AS THE LOW PRESSURE AREA  
CONTINUES TO HEAD SOUTH TOWARDS BAJA CALIFORNIA.  
 
WINDS WILL SHIFT BACK TO THE SOUTH TOMORROW AS A WEAK WEATHER FRONT  
MOVES TOWARDS NW CALIFORNIA. WINDS WILL BE FAIRLY LIGHT AND VARIABLE  
AFTER THAT AS PRESSURE GRADIENT OVER THE AREA REMAINS WEAK.  
 
WE WILL HAVE ANOTHER SIGNIFICANT WESTERLY SWELL GROUP MOVING INTO  
THE NW CALIFORNIA WATERS WEDNESDAY EVENING INTO THURSDAY. THE WAVE  
HEIGHT IS PROGGED TO BE UP TO 16 FEET. HOWEVER, THE WAVE PERIOD WILL  
BE AS LONG AS 20 SECONDS. /RCL  
 

 
   
BEACH HAZARDS (HIGH SURF AND SNEAKER WAVE POTENTIAL)
 
NW  
CALIFORNIA IS FINALLY OUT OF THE THREAT OF HIGH SURF. THE WESTERLY  
SWELL HAS SUBSIDED EARLY THIS MORNING. HOWEVER, WE WON'T HAVE TOO  
MUCH OF A BREAK BEFORE THE HAZARDOUS CONDITIONS RETURN TO AREA  
BEACHES. MODELS ARE SHOWING SNEAKER WAVE POTENTIAL TOMORROW  
AFTERNOON INTO THE EVENING HOURS, AHEAD OF THE NEXT HIGH SURF  
EVENT. THE NEXT HIGH SURF EVENT IS EXPECTED TO IMPACT AREA BEACHES  
LATE WEDNESDAY NIGHT INTO THURSDAY. RIGHT NOW, MODELS ARE SHOWING  
THE SURF HEIGHTS AROUND 22 TO 25 FEET, WHICH IS IN THE RANGE OF  
HIGH SURF ADVISORY. /RCL  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
 
NORTHWEST CALIFORNIA COASTAL WATERS...  
SMALL CRAFT ADVISORY UNTIL 9 AM PST THIS MORNING FOR PZZ450-470.  
SMALL CRAFT ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR PZZ455-475.  
 

 
 

 
 
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