210  
FXUS66 KEKA 111223  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
423 AM PST SUN DEC 11 2016  
   
SYNOPSIS
 
 
A FEW SHOWERS, WITH HIGHER ELEVATION SNOW SHOWERS, REMAIN POSSIBLE  
THROUGH MONDAY MORNING FOR LOCATIONS ALONG AND NORTH OF HIGHWAY 299.  
AFTER A BRIEF DRY SPELL FOR THE LATTER HALF OF MONDAY INTO TUESDAY  
MORNING, WIDESPREAD RAINFALL AND HIGHER ELEVATION SNOWS WILL DEVELOP  
FROM SOUTHWEST TO NORTHEAST ON TUESDAY, BECOMING WIDESPREAD FOR  
WEDNESDAY THROUGH FRIDAY.  
 

 
   
DISCUSSION
 
 
   
SHORT TERM
 
 
(TODAY THROUGH MONDAY)  
 
A FEW LIGHT SHOWERS CONTINUE TO DEVELOP OVER THE OPEN WATERS EARLY  
THIS MORNING, OCCASIONALLY MAKING IT ASHORE ALONG THE REDWOOD COAST  
BEFORE DYING OUT FARTHER INLAND. THIS IS OCCURRING DUE TO WEAK  
ASCENT ALOFT, COURTESY OF A SHORTWAVE TROUGH PASSING BY TO OUR  
NORTH. AS DAYTIME HEATING COMMENCES, THE MODELS SHOW SHOWER COVERAGE  
BECOMING A LITTLE MORE ROBUST (ALTHOUGH STILL NOTHING TO WRITE HOME  
ABOUT), AS THEY AFFECT AREAS MAINLY NORTH OF HIGHWAY 299. SNOW  
LEVELS RUNNING AROUND 3500 FEET WILL ALLOW PERHAPS A LIGHT DUSTING  
OF SNOW FOR THE HIGHER ELEVATIONS, WITH DEL NORTE COUNTY SEEING THE  
BEST CHANCE OF RECEIVING ANY PRECIPITATION. PRECIPITATION CHANCES  
WILL SIGNIFICANTLY DIMINISH AFTER SUNSET, BUT A STRAY SHOWER CAN'T  
BE RULED OUT OVERNIGHT.  
 
OTHERWISE, SEASONABLY COOL TEMPERATURES AND DRY CONDITIONS ARE  
EXPECTED TO DOMINATE THE REMAINDER OF NORTHWEST CALIFORNIA THROUGH  
MONDAY NIGHT.  
   
LONG TERM
 
 
(TUESDAY THROUGH SATURDAY)  
 
NUMERICAL MODEL CONTINUITY CONTINUES TO INCREASE FOR THE MIDDLE OF  
THE WEEK STORM SYSTEM, MAKING THE FORECAST "A LITTLE LESS FOGGY"  
(PARDON THE PUN). PRIOR TO THE LAST 36 TO 48 HOURS, THE ECMWF MODEL  
HAD REMAINED CONSISTENT, WITH THE GFS TRENDING TOWARDS ITS EUROPEAN  
COUNTERPART. THEN FOR THE FIRST HALF OF YESTERDAY, THE TWO FLIPPED  
THEIR SOLUTIONS, BEFORE THE ECMWF (EURO) TRENDED BACK TOWARDS IT  
INITIAL SOLUTION.  
 
WHAT THEY NOW SHOW IS A LEAD VORT MAX, WITH A WEAK SURFACE LOW  
(AROUND 1012MB) PASSING BY JUST SOUTH OF THE FORECAST AREA. THE GFS  
MODEL INDICATE A WARM FRONT APPROACHING THE SOUTHERN MENDOCINO  
COUNTY BORDER BY LATE TUESDAY, WITH AN OVER-RUNNING PRECIPITATION  
SCENARIO DEVELOPING FROM ABOUT WILLITS SOUTHWARD. THE NAM AND EURO  
AGREE WITH THIS SOLUTION, BUT, SPREAD THE PRECIP INTO FAR SOUTHERN  
HUMBOLDT AND TRINITY COUNTY.  
 
AS ONE SYSTEM DEPARTS THE REGION EARLY WEDNESDAY MORNING, ANOTHER  
SYSTEM QUICKLY ON ITS HEELS WILL ALREADY BE INFLUENCING OUR WEATHER.  
ALL MODELS (THE CURRENT NAM RUN ONLY EXTENDS THROUGH 18Z WEDNESDAY,  
BUT ITS EXTRAPOLATION AGREES) BRING A SURFACE LOW ACROSS THE AREA,  
LIFTING A WARM FRONT THROUGH CENTRAL PORTIONS OF THE FORECAST AREA,  
WITH WIDESPREAD MODERATE TO LOCALLY HEAVY RAINFALL DEVELOPING. THIS  
FRONT LOOKS TO STALL ALONG A LINE FROM THE KINGS RANGE TO NEAR  
ORLEANS DURING THE DAY, WITH ANOTHER LOW TREKKING ALONG THE FRONT FOR  
THURSDAY. STRONG LOW-LEVEL CONVERGENCE IS EXPECTED WITH THESE  
FEATURES, AIDING IN PRECIPITATION GENERATION AND INTENSITY. WHILE  
THE GFS IS MUCH STRONGER WITH THE SECOND LOW (HAS BEEN FOR THE LAST  
SEVERAL RUNS, SHOWING A LOW IN THE 992 TO 997MB RANGE VERSUS THE  
EURO SHOWING A PAIR OF LOWS NEAR 1007MB), IT SHOWS SIMILAR  
PRECIPITATION AMOUNTS, WITH BOTH MODELS SHOWING A WIDESPREAD 3 TO 6  
INCHES OF RAINFALL ACROSS HUMBOLDT, TRINITY, AND MENDOCINO COUNTIES,  
WITH ABOUT AN INCH LESS FOR DEL NORTE. THE CANADIAN WAS MUCH FARTHER  
SOUTH THAN THE OTHER THREE MODELS AND ITS FORECAST WAS DISCOUNTED.  
 
SO OVERALL, THE GENERAL THEME IS FOR A MUCH WETTER MIDDLE TO END OF  
THE WORK WEEK, WITH HIGHER ELEVATION SNOWFALL LIKELY (POSSIBLY  
SEVERAL INCHES IN SOME SPOTS), WITH CONTINUED SEASONABLY COOL  
TEMPERATURES STICKING AROUND. HIGH PRESSURE AND DRYING CONDITIONS  
WILL ARRIVE JUST IN TIME FOR THE WEEKEND (ASSUMING THE IMPROVED  
MODEL STABILITY DISINTEGRATE OVER THE NEXT FEW DAYS). /PD  
 

 
   
AVIATION
 
 
PREDOMINATELY VFR CONDITIONS AND LIGHT WINDS WILL CONTINUE AT KCEC,  
KACV AND KUKI TODAY. HOWEVER MVFR CONDITIONS MAY OCCUR AT TIMES DUE TO LIGHT  
SHOWERS MOVING ACROSS THE REGION AND/OR PATCHY FOG REDUCING CEILINGS AND/OR  
VISIBILITIES.  
 

 
   
MARINE
 
 
LIGHT TO MODERATE WINDS WILL CONTINUE ACROSS THE WATERS THIS WEEK.  
SEAS SUBSIDED SLIGHTLY TODAY. THE NORTHWEST SWELL PROPAGATING ACROSS THE WATERS  
WILL GRADUALLY SUBSIDE MONDAY AND TUESDAY. THERE IS A SLIGHT CHANCE TO CHANCE  
FOR SHOWERS MOVING ACROSS THE REGION AT TIMES THROUGH MONDAY. WINDS AND SEAS  
MAY INCREASE IN OR NEAR ANY SHOWERS.  
 

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

 
 

 
 
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FOR FORECAST ZONE INFORMATION  
SEE THE FORECAST ZONE MAP ONLINE:  
HTTP://WWW.WEATHER.GOV/EUREKA/ZONEMAP.PNG  
 
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