823  
FXUS66 KEKA 241152  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
352 AM PST MON NOV 24 2014  
   
SYNOPSIS
 
A WEAK WARM FRONT MAY BRING SOME LIGHT RAIN OR  
SPRINKLES TODAY FOR AREAS PRIMARILY NORTH OF CAPE MENDOCINO. HIGH  
PRESSURE AND DRY CONDITIONS RETURN TUESDAY THROUGH THURSDAY  
MORNING. WET WEATHER RETURNS THURSDAY AFTERNOON INTO THE WEEKEND.  
 

 
   
SHORT TERM (THROUGH THURSDAY)
 
A WEAK WARM FRONT CONTINUES TO  
APPROACH THE COAST THIS MORNING. RAIN AMOUNTS LOOK TO BE VERY  
LIGHT WITH THIS FRONT. MODELS HAVE PUSHED BACK MOST OF THE RAIN  
UNTIL LATE MORNING OR AFTERNOON. THERE MAY STILL BE SOME SPRINKLES  
IN THE MORNING NORTH OF CAPE MENDOCINO WITH AREAS TO THE SOUTH  
REMAINING MAINLY DRY. RAINFALL AMOUNTS WILL RANGE FROM A TRACE TO  
A TENTH OF AN INCH OVER THE HIGHER TERRAIN IN DEL NORTE COUNTY.  
FOG IS BEING REPORTED IN THE VALLEYS OF TRINITY AND MENDOCINO  
COUNTIES. THIS WILL LIKELY SLOW DOWN THE WARMING ONCE AGAIN IN  
THESE VALLEYS.  
 
TUESDAY AND WEDNESDAY WILL BE MAINLY CLEAR EACH DAY WITH THE  
EXCEPTION OF THE INLAND VALLEYS WHERE THERE WILL BE NIGHT AND  
MORNING FOG. THIS WILL LIKELY BE SLOW TO CLEAR EACH  
DAY...ESPECIALLY IN TRINITY COUNTY SO HAVE LOWERED THE HIGH  
TEMPERATURES THERE. MORNING TEMPERATURES WILL BE CHILLY...ALTHOUGH  
IT REMAINS TO BE SEEN HOW MUCH FOG WILL BE PRESENT TO KEEP  
TEMPERATURES A BIT WARMER. TUESDAY MORNING WILL LIKELY BE THE  
COLDEST...BY WEDNESDAY THE SOUTHEASTERLY WINDS START TO INCREASE  
AHEAD OF THE THE NEXT SYSTEM. AT THIS POINT IT DOES NOT APPEAR  
THERE WILL BE FROST IN THE COASTAL ZONES OR NORTH COAST INTERIOR  
ZONE (INTERIOR PORTIONS OF HUMBOLDT AND DEL NORTE COUNTY)...BUT  
THIS WILL NEED TO BE WATCHED AS IT GETS CLOSER.  
 
THE 00Z GFS HAS SPED UP THE FRONT SLIGHTLY AND IS NOW BRINGING  
RAIN TO THE NORTH COAST IN THE AFTERNOON ON THANKSGIVING DAY. THE  
ECMWF HAS COME INTO BETTER AGREEMENT WITH THE GFS AND IS ALSO  
BRINGING SOME LIGHT RAIN IN ON THURSDAY AFTERNOON. SO HAVE  
INCREASED POPS SLIGHTLY FOR THE NORTH COAST ON THURSDAY AFTERNOON  
THIS WILL NEED TO BE MONITORED AS IT GETS CLOSER. SNOW LEVELS WILL  
BE MAINLY HIGH WITH THIS SYSTEM...ALTHOUGH THERE COULD BE SOME  
COLD AIR TRAPPED IN THE WEAVERVILLE TO TRINITY LAKE AREA WHICH  
COULD LOWER SNOW LEVELS A BIT EARLY ON. MKK  
 
LONG TERM...(FRIDAY THROUGH MONDAY) ONCE THE FRONT MOVES  
ONSHORE...EITHER DURING THE DAY THURSDAY OR THURSDAY  
NIGHT...WET CONDITIONS WILL PERSIST FOR SEVERAL DAYS. WAVES OF  
UPPER LEVEL ENERGY IN ONSHORE FLOW ADVANCE TOWARD THE COAST FRIDAY  
THROUGH SUNDAY. MODELS ARE STILL IN REMARKABLE CONSISTENCY ON THIS  
PATTERN WITH WIDESPREAD PRECIPITATION EXPECTED FOR THE AREA. THERE  
ARE DIFFERENCES IN THE TIMING OF EACH WAVE OF PRECIPITATION AND  
WHERE EXACTLY THE HEAVIEST PRECIPITATION FALLS ACROSS NORTHWEST  
CALIFORNIA...BUT CONFIDENCE IS VERY HIGH THAT WE ARE HEADED INTO A  
WET PERIOD. THE GFS AND ECMWF BOTH CURRENTLY PREDICT A TOTAL OF 2  
TO 6 INCHES OF RAIN FROM LATE THURSDAY THROUGH SUNDAY...WITH THE  
HIGHEST AMOUNTS IN THE MOUNTAINS AS USUAL. SNOW WILL REMAIN HIGH  
THROUGH EARLY SUNDAY WITH A WARM AIRMASS IN PLACE WITH TROPICAL  
ORIGINS. SUNDAY NIGHT INTO THERE IS FAIRLY GOOD MODEL AGREEMENT  
THAT THE UPPER LEVEL TROUGH WILL MOVE OVERHEAD AND SNOW LEVELS  
WILL FALL BELOW 4000 FT AND MAY CAUSE TRAVEL DIFFICULTIES ON THE  
HIGHER PASSES. MKK/RPA  
 

 
   
AVIATION
 
MUCH OF NORTHERN CALIFORNIA WILL WAKE UP TO VFR  
CONDITIONS TODAY WITH THE EXCEPTION OF AREAS OF IFR ACROSS  
INTERIOR VALLEYS AND POSSIBLY SMALL POCKETS ALONG THE COAST.  
INTERIOR VALLEY FOG SHOULD DISSIPATE BY LATE MORNING. A PASSING  
WARM FRONT WILL CAUSE CEILINGS TO GRADUALLY LOWER ACROSS THE  
REGION TODAY WITH PERIODIC LIGHT RAIN POSSIBLE FOR AIRFIELDS NORTH  
OF CAPE MENDOCINO. THERE IS STILL SOME UNCERTAINTY AS TO WHEN  
CONDITIONS WILL DETERIORATE AND TO WHAT DEGREE. ULTIMATELY DECIDED  
TO CONTINUE TO TREND CLOSER WITH THE NAM. EXPECT MVFR CONDITIONS  
FOR AREAS NORTH OF CAPE MENDOCINO BY LATE AFTERNOON WITH PERIODS  
OF IFR CONDITIONS POSSIBLE TONIGHT. AREAS FARTHER INLAND AND SOUTH  
OF CAPE MENDOCINO CAN EXPECT VALLEY FOG ONCE AGAIN TONIGHT WITH  
OTHERWISE VFR CONDITIONS ELSEWHERE.  
 

 
   
MARINE
 
A WARM FRONT WILL TRAVERSE ACROSS THE WATERS TODAY  
RESULTING IN MINIMAL MARINE IMPACTS INCLUDING A SLIGHT INCREASE IN  
WINDS OFFSHORE AND PERIODS OF LIGHT RAIN. LIGHT TO MODERATE WINDS  
SHALL PERSIST THROUGH THE EARLY HALF OF THE WEEK AS HIGH PRESSURE  
OVER HEAD MAINTAINS A WEAK GRADIENT. FURTHERMORE A NORTHWESTERLY  
WAVE WILL SLOWLY SUBSIDE TODAY THROUGH MID-WEEK. SEA HEIGHTS WILL  
FLUCTUATE NEAR 10 FEET MID-DAY AND SHOULD FURTHER SUBSIDE TO  
AROUND 8 TO 9 FEET AT 13 SECONDS BY TONIGHT. CONSEQUENTLY, SMALL  
CRAFT ADVISORIES SHOULD BE GOOD TO EXPIRE BY LATE THIS AFTERNOON.  
A LOW PRESSURE SYSTEM WILL THEN APPROACH THE REGION CAUSING  
INCREASING SOUTHERLY WINDS AND BUILDING SEAS ACROSS THE COASTAL  
WATERS BY WEDNESDAY/THURSDAY. BEYOND THAT LITTLE WAS CHANGED IN  
THE FORECAST OVER THE WEEKEND AS MODELS STILL EXHIBIT DIFFERENCES  
IN TIMING OF THIS MAIN SYSTEM AND THE SUBSEQUENT DISTURBANCES.  
THUS I CONTINUED TO SKEW TOWARDS ECMWF FOR THE WEEKEND WINDS BUT  
LOWERED THEM SLIGHTLY TO FALL INTO CONSISTENCY WITH NEIGHBORS.  
/KML  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
NORTHWEST CALIFORNIA COASTAL WATERS...  
SMALL CRAFT ADVISORY UNTIL 2 PM PST THIS AFTERNOON FOR  
PZZ450-455-470-475.  
 

 
 

 
 
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