156  
FXUS02 KWBC 061614  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1113 AM EST TUE MAR 06 2018  
 
VALID 12Z FRI MAR 09 2018 - 12Z TUE MAR 13 2018  
 
...POTENTIAL STILL EXISTS FOR ANOTHER EAST COAST WINTER STORM  
EARLY NEXT WEEK...  
 
...PATTERN HIGHLIGHTS/THREATS AND GUIDANCE/PREDICTABILITY  
ASSESSMENT...  
 
MODEL GUIDANCE THIS MORNING CONTINUES TO DEPICT AN ACTIVE AND HIGH  
AMPLITUDE UPPER-LEVEL PATTERN WITH A BLOCKING REGIME ACROSS THE  
HIGH LATITUDES THAT MAKES IT PRONE TO RAPID CYCLOGENESIS IN THE  
MID LATITUDES. THE FIRST OF THESE CYCLONE IS FORECAST TO OCCUR IN  
THE SHORT RANGE NEAR THE NORTHEAST U.S. COAST. THIS STORM IS  
FORECAST TO SLOWLY SPIN DOWN OVER NORTHERN NEW ENGLAND ON DAY 3  
FRIDAY AS A WEAKENING FRONT AND AN UPPER TROUGH MOVE INTO THE  
WESTERN U.S. THE VORTICITY ASSOCIATED WITH THIS TROUGH IS  
FORECAST TO MOVE OUT THE ROCKIES AND INTO THE PLAINS ON DAY 5  
SUNDAY...AND THAT IS WHEN THE MODEL SOLUTIONS BEGIN TO DIVERGE.  
THE SUBSEQUENT DEVELOPMENT OF THIS SYSTEM WILL HAVE SIGNIFICANT  
IMPLICATIONS TO THE POTENTIAL OF ANOTHER EAST COAST WINTER STORM  
SOME TIME EARLY NEXT WEEK. THE LAST FEW DETERMINISTIC RUNS FROM  
THE ECMWF HAVE QUICKLY TRENDED TOWARD A FLATTER/NON-DEVELOPING  
SOLUTION FROM DAY 5 ONWARD...IN CONTRAST WITH THE GFS WHICH  
CONTINUES TO INDICATE A SIGNIFICANT NOR'EASTER JUST OFF THE  
MID-ATLANTIC COAST ON DAY 6 MONDAY. NEVERTHELESS...THE 00Z EC  
MEAN CONTINUES TO SUPPORT THE IDEA OF CYCLOGENESIS OFF THE  
CAROLINA COAST ON MONDAY WHICH IS IN GOOD AGREEMENT WITH THE 00Z  
AND 06Z GEFS MEANS. THE REASON FOR THE ECMWF'S TREND TOWARD A  
FLATTER SOLUTION IN THE EAST APPEARS TO BE A TREND TOWARD A MORE  
AMPLIFIED RIDGE IN THE WEST WITH ITS AXIS NUDGING SLIGHTLY MORE  
TOWARD THE EAST. HOWEVER...GIVEN THE HIGH AMPLITUDE NATURE OF THE  
UPPER-LEVEL FLOW ACROSS THE U.S. EARLY NEXT WEEK AND THE FACT THAT  
BOTH THE EC AND GEFS MEANS ARE IN AGREEMENT...IT APPEARS THAT EAST  
COAST CYCLOGENESIS REMAINS THE MORE LIKELY OUTCOME FOR EARLY NEXT  
WEEK. THE WPC MORNING GRID PACKAGES ARE A BLEND OF THE 00Z ECMWF  
AND THE 06Z GFS SOLUTIONS...TRENDING MORE TOWARD THEIR ENSEMBLE  
MEANS ON DAY 5...AND CONSISTING OF MOSTLY THEIR ENSEMBLE MEANS ON  
DAY 7.  
 
KONG  
 

 
 
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