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Sorry about the length of the post. Forecaster is very good with the week ahead forecast. Starting Wednesday Morning. Models can be inaccurate! Bold emphasis added~danielw Posted one hour after transmission: EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 203 PM EDT SUN MAY 13 2012 VALID 12Z WED MAY 16 2012 - 12Z SUN MAY 20 2012 ...COASTAL LOW/NOR'EASTER POSSIBLE NEAR THE CAROLINAS NEXT WEEKEND... OUTSIDE THE 00Z CANADIAN GUIDANCE BEYOND FRIDAY MORNING...THE AVAILABLE DETERMINISTIC AND ENSEMBLE MEAN GUIDANCE IS IN VERY GOOD AGREEMENT CONCERNING THE EXPECTED FLOW PATTERN. TROUGHING BECOMES ESTABLISHED ACROSS THE INTERMOUNTAIN WEST WHILE RIDGING EXISTS ACROSS THE PLAINS/MIDWEST AND A DEEP CYCLONE MOVES OFFSHORE THE SOUTHEAST COAST. SINCE THERE WAS SUCH GOOD AGREEMENT...USED A 40/30/30 BLEND OF THE 00Z UKMET/00Z GFS/00Z ECMWF THROUGH FRIDAY BEFORE SWITCHING TO A 50/50 BLEND/COMPROMISE OF THE 00Z GFS AND 00Z ECMWF SOLUTIONS. THIS PREFERENCE LED TO GOOD CONTINUITY. THE DEEP CYCLONE/NOR'EASTER FORECAST OFFSHORE THE SOUTHEAST COAST THIS WEEKEND HAS A CHANCE TO BECOME A HYBRID SYSTEM AS IT HOVERS NEAR THE WARM GULF STREAM WATERS FROM FRIDAY INTO EARLY THE FOLLOWING WEEK. EVEN IF IT REMAINS COLD CORE...THE SYSTEM SHOULD LEAD TO LOWERED PRESSURES/DISTURBED WEATHER ACROSS THE WESTERN CARIBBEAN LATE IN THE PERIOD NEAR THE BASE OF ITS UPPER TROUGH/COLD FRONT...NORMALLY A PROBLEM WHEN A DEEP LAYERED CYCLONE FORMS BETWEEN THE SOUTHEAST AND BERMUDA. HEAVY COMMA HEAD RAINS/WINDY CONDITIONS ARE POSSIBLE NEAR THE CAROLINA/GEORGIA/NORTHEAST FLORIDA COAST IF THE SYSTEM TAKES A MORE COASTAL ROUTE AS SEEN IN THE 00Z ECMWF. IF IT DEVELOPS AND STAYS FARTHER OFFSHORE...IT COULD EVOLVE INTO A WILDFIRE CONCERN FOR SOUTH CAROLINA/GEORGIA/NORTHERN FLORIDA WHICH ARE WITHIN THEIR ANNUAL SPRING DROUGHT...SIMILAR TO THE SITUATION SEEN DURING SUBTROPICAL STORM ANDREAS DEVELOPMENT DURING EARLY MAY 2007. THE POTENTIAL DEVELOPMENT AS SEEN BY ECMWF OVER THE PAST SEVERAL RUNS IS DIFFERENT THAN THAT OF 2007 EVOLUTION OF ANDREAS...BUT THE FINAL DEVELOPMENT OF ANDREAS INTO ITS SUBTROPICAL FORM IS SIMILAR IN THE MID LEVEL H500 FLOW OF THIS EVENT. VELOCITY POTENTIAL ANOMALIES OF GFS/ECMWF/CMC CONTINUE TO INDICATE A FAVORABLE ENVIRONMENT FOR TROPICAL DEVELOPMENT IN THE EASTERN PACIFIC/WESTERN CARRIBEAN AND OFF THE U.S. SOUTHEASTERN SEABOARD. THE EASTERN PACIFIC ALREADY HAS A SYSTEM READY TO GO AND WILL LIKELY BE AT LEAST A TROPICAL DEPRESSION IN THE NEXT DAY OR SO. SEE NHC DISCUSSIONS. THE ATLANTIC SIDE OFF THE SOUTHEASTERN SEABOARD ALSO HAS FAVORABLE CONDITIONS AS MENTIONED ABOVE WITH A LARGE NUMBER OF ECMWF ENSEMBLE MEMBERS SUPPORTING THE OPERATIONAL RUN WITH THE SYSTEM LATE NEXT WEEK AND WEEKEND. BEYOND THIS TIME FRAME LONGER TERM RUNS OF GFS HAVE BEEN PRODUCING TROPICAL SYSTEMS IN THE WESTERN CARRIBEAN WITH AN EXIT NORTH AND NORTHEASTWARD. THIS IS ANOTHER INDICATION THAT THE MODELS RECOGNIZE FUTURE FAVORABLE DEVELOPMENT CONDITIONS OR CYCLOGENESIS. UPDATED MORNING PRELIMS REMAIN SIMILAR TO THE OVERNIGHT PACKAGE WITH AN ADJUSTMENT OF THE SOUTHEASTERN SEABOARD LOW SOUTHWARD OF THE EARLY PRELIMS OFF THE SC COAST AS A BETTER FIT TO LAGGED AVERAGE FORECASTS OF ECMWF AND GFS. AFTernooN FINALS REMAIN THE SAME. ADDITIONAL SUPPORT FOR EARLIER PROGS BY HIRES UKMET OVER CONUS AND ADJACENT WATERS. SOUTHEAST SEABOARD LOW FORECAST SE OF CAPE FEAR IN GOOD AGREEMENT WITH 00Z ECMWF DAYS 6-7. ROTH/ROSENSTEIN |