559  
FXUS66 KEKA 271128  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
428 AM PDT MON APR 27 2015  
   
SYNOPSIS
 
A RIDGE OF HIGH PRESSURE OVER THE WEST COAST WILL  
BRING DRY WEATHER AND INTERIOR TEMPERATURES WELL ABOVE NORMAL  
TODAY. EXPECT INTERIOR TEMPERATURES TO COOL TUESDAY AND WEDNESDAY  
AS THE RIDGE SHIFTS INLAND AND A TROUGH PASSES OVER THE PACIFIC  
NORTHWEST. INTERIOR TEMPERATURES WILL TREND UPWARD THE SECOND HALF  
OF THE WEEK AS HIGH PRESSURE DOMINATES THE WEATHER PATTERN.  
 

 
   
DISCUSSION
 
A RIDGE OF HIGH PRESSURE OVER THE WEST COAST WILL  
BRING DRY WEATHER TO NORTHWEST CALIFORNIA TODAY. WITH THE RIDGE  
NEARLY OVERHEAD INTERIOR TEMPERATURES WILL CONTINUE TRENDING  
UPWARD TODAY, RISING WELL ABOVE NORMAL ALONG WITH SOME HIGH LEVEL  
CLOUDS. WIDESPREAD VALLEY TEMPERATURES IN THE 80S ARE FORECASTED  
TODAY AND A FEW 90S ARE NOT OUT OF THE QUESTION. THE COAST CAN  
EXPECT SEASONAL TEMPERATURES IN THE 50S AND 60S. THOUGH, THE  
IMMEDIATE REDWOOD COAST MAY STAY UNDER STRATUS MOST OF TODAY DUE  
TO WEAK NORTHWEST FLOW. SOME CLEARING IS POSSIBLE FOR A SHORT TIME  
THIS AFTERNOON, BUT UNCERTAINTY IS HIGH AND CLOUDS WILL PROBABLY  
RETURN TONIGHT. INTERIOR TEMPERATURES WILL BEGIN TRENDING DOWNWARD  
ON TUESDAY AS THE RIDGE SHIFTS INLAND AND A TROUGH APPROACHES FROM  
THE PACIFIC. BUT EVEN WITH THE TEMPERATURES TRENDING DOWNWARD,  
THEY WILL REMAIN A FEW DEGREES ABOVE NORMAL ON TUESDAY. THE TROUGH  
WILL APPROACH ON TUESDAY AND AN ASSOCIATED VERY WEAK DISTURBANCE  
WILL PASS TO OUR NORTH TUESDAY MORNING. THIS WILL BRING US SOME  
HIGH LEVEL CLOUDS AND A SLIGHT CHANCE OF VERY LIGHT RAIN SHOWERS  
TO DEL NORTE COUNTY. WILL EMPHASIZE THE ODDS OF THIS ARE LOW, BUT  
NOT ZERO. ANY QPF WILL BE BARELY MEASURABLE. MODELS SHOW THE  
TROUGH MOVING OVER US LATE TUESDAY INTO WEDNESDAY, BRINGING COOLER  
TEMPERATURES. NO PRECIPITATION IS EXPECTED. AS A RESULT, POPS  
REMAIN BELOW CLIMO DURING THIS TIME PERIOD. ZONAL FLOW DEVELOPS  
THURSDAY AND CONTINUES THROUGH THE END OF THE WEEK. THOUGH, THE  
MODELS HINT AT A CUTOFF LOW DEVELOPING OFF THE COAST OF SOUTHERN  
CALIFORNIA TOWARDS THE END OF THE WEEK. WILL KEEP AN EYE ON THIS  
AS IT COULD LEAD TO SHOWERS OR MAYBE THUNDERSTORMS LATE THIS WEEK.  
BUT IT'S TOO FAR OUT TO KNOW FOR SURE AT THIS POINT. OTHERWISE,  
THE CONSMODEL WAS USED FOR TEMPERATURES DURING THAT TIME PERIOD  
AND IT HAS THEM REMAINING SEASONAL ALONG THE COAST AND TRENDING  
BACK UP (ABOVE NORMAL) ACROSS THE INTERIOR.  
 

 
   
AVIATION
 
AFTER A MORNING OF PATCHY LOW CLOUDS ALONG THE COAST,  
CIGS SHOULD LIFT ALLOWING FOR A VFR DAY. HIGH CLOUDS WILL BE  
STREAMING OVER NW CAL TODAY AS WEAK HIGH PRESSURE BEGINS TO SHIFT  
TO THE EAST. VFR WILL PREVAIL ACROSS NW CAL THROUGH TONIGHT WITH  
EXCEPTION OF THE COASTAL AREAS. MODELS SHOW AN ONSHORE PUSH  
DEVELOPING THIS EVENING AND THE BOUNDARY LAYER MOISTURE INCREASING  
AS WE GO INTO TONIGHT. THIS SHOULD BRING IN SOME LOW CLOUDS ACROSS  
COASTAL AREAS. WITH A DEEPENING MARINE LAYER DUE TO THE  
APPROACHING FRONT, THERE COULD BE DEEPER PENETRATION OF THE LOW  
CLOUDS UP THE RIVER VALLEYS. SOMETHING TO WATCH FOR THIS EVENING.  
BFG  
 

 
   
MARINE
 
HIGH PRESSURE WILL SHIFT OFF TO THE EAST TODAY AHEAD OF  
AN APPROACHING UPPER TROUGH AND ITS WEAK SURFACE FRONT. THIS FRONT  
IS FORECAST TO CLIP THE NORTHERN WATERS TUESDAY EVENING, BRINGING  
SOUTHERLY WINDS WHILE LEAVING NORTHERLY WINDS ACROSS THE SOUTHERN  
WATERS. IF THE FRONT COMES IN A BIT STRONGER WINDS WILL SHIFT TO  
THE SOUTH ACROSS ALL COASTAL WATERS, BUT MODELS ARE FAIRLY  
CONSISTENT YIELDING MODERATE TO HIGH CONFIDENCE. A NW SWELL WILL  
BEGIN TO BUILD INTO THE WATERS ON TUESDAY, GENERATED FROM A BROAD  
AREA OF LOW PRESSURE SPINNING IN THE GULF OF ALASKA. LOOK FOR  
HEIGHTS TO BUILD TO AROUND 8 TO 11 FT AT ABOUT 12 SECONDS LATE  
TUESDAY INTO WEDNESDAY. SMALL CRAFT ADVISORIES WILL LIKELY BE  
NEEDED SOMETIME TUESDAY FOR MOST OF THE WATERS. THIS DEPENDS ON  
HOW FAST THE WINDS INCREASE AND WHEN THE SWELL ARRIVES.  
REGARDLESS, AS HIGH PRESSURE SURGES IN BEHIND TUESDAYS WEAK FRONT  
NORTHERLY CONDITIONS WILL INCREASE SHARPLY. SMALL CRAFT ADVISORIES  
WILL BE NEED FOR ALL WATERS BY WEDNESDAY MORNING DUE TO SEAS. AT  
THIS POINT, WE ARE LOOKING AT THE POTENTIAL OF GALE CONDITIONS  
DEVELOPING BY THURSDAY AFTERNOON ACROSS THE OUTER WATERS. WE WILL  
NEED TO SEE HOW MODELS HANDLE THIS OVER THE COMING CYCLES, BUT WE  
MAY NEED TO ISSUE A GALE WATCH FOR THURSDAY. HIGH PRESSURE IS  
EXPECTED TO MAINTAIN FRESH TO STRONG WINDS OVER THE OUTER WATERS  
THROUGH THE WEEKEND WHILE THE INNER WATERS WILL BE IN MORE OF A  
DIURNAL TREND WITH HIGHER WINDS EACH AFTERNOON AND EVENING. BFG  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
 
NORTHWEST CALIFORNIA COASTAL WATERS...NONE.  
 

 
 

 
 
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