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