000 FXUS02 KWBC 061854 PMDEPD EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 153 PM EST FRI NOV 06 2009 VALID 12Z MON NOV 09 2009 - 12Z FRI NOV 13 2009 NERN PAC TROF ENERGY IS FCST TO PROGRESS INTO NORTH AMERICA DURING THE MEDIUM RANGE PERIOD. THE 00Z GEFS AND ECMWF/CANADIAN ENSEMBLES SHOW SOME SPREAD/A FEW MEMBER OUTLIERS BUT BY DAY 7 FRI THEIR MEANS GENERALLY AGREE IN SHOWING A POSITIVELY TILTED TROF EXTENDING FROM NEAR CNTRL CANADA INTO THE SWRN CONUS. THE 00Z GFS AND ECMWF DIFFER FROM THE ENSEMBLE MEAN CONSENSUS BY SEPARATING NRN AND SRN STREAM FLOW... YIELDING AN ONTARIO/NRN CONUS SHRTWV BY EARLY FRI AND A SEPARATE TROF OVER THE SOUTHWEST. PRIOR ECMWF RUNS GENERALLY DID NOT SHOW THE DEGREE OF SEPARATION DISPLAYED BY THE 00Z ECMWF/GFS OR AT LEAST WERE SLOWER WITH THE NRN PART OF THE MEAN TROF... WHILE INDIVIDUAL GFS RUNS HAVE BEEN SOMEWHAT INCONSISTENT WITH DETAILS. TELECONNECTIONS RELATIVE TO A CORE OF NEGATIVE HGT ANOMALIES SETTLING OVER THE AK MAINLAND BY D+8... AND POSITIVE ANOMALIES OVER THE NWRN PAC... OFFER SUPPORT FOR SOME DEGREE OF FLOW SEPARATION OVER NOAM. HOWEVER SINCE THE NWRN PAC/AK PATTERN IS ACHIEVED ONLY BY THE END OF THE PERIOD IT COULD STILL TAKE A LITTLE TIME FOR THE TELECONNECTION FAVORED FLOW TO EVOLVE DOWNSTREAM. TELECONNECTION CONSIDERATIONS ALONG WITH LACK OF PRONOUNCED CONTINUITY WITH THE 00Z GFS/ECMWF SCENARIO FAVOR A COMPROMISE BETWEEN THE GFS/ECMWF AND ENSEMBLE MEAN CLUSTERS. FARTHER EWD THE GFS/ECMWF/UKMET ALL INDICATE THAT MID LVL ENERGY OVER CNTRL NOAM AS OF DAY 3 MON MAY CLOSE OFF A FAIRLY VIGOROUS CLOSED LOW OVER/NEAR THE NORTHEAST BY MIDWEEK WHILE THE CANADIAN IS MORE SHEARED. RUN TO RUN CONTINUITY IN OPERATIONAL MODELS HAS YET TO STABILIZE... ENSEMBLES FAVOR MAINTAINING A PROGRESSIVE TROF... AND THE RECENT/CURRENT REGIME HAS BEEN FAIRLY PROGRESSIVE. THUS IT APPEARS BEST TO LEAN SOMEWHAT FASTER/WEAKER THAN THE 00Z GFS/ECMWF AT THIS TIME BUT NOT TO THE EXTENT OF THE ENSEMBLE MEANS. CURRENT T.D. IDA IS EXPECTED TO STRENGTHEN TO TROPICAL STORM STATUS AS IT TRACKS INTO THE GULF OF MEXICO FROM THE NWRN CARIBBEAN DURING THE SHORT RANGE PERIOD. MANUAL FORECAST REPRESENTS TRACK POINTS FROM THE 15Z TPC ADVISORY...WITH WEAKENED HPC/TPC COORDINATED DAYS 5-7 EXTRATROPICAL LOW POSITIONS CONSISTENT WITH EXPECTED INCREASED SHEAR AND COOLER WATER TEMPS...AND HELD IN PLACE IN LUE OF SIGNIFICANT MODEL TRACK/STRENGTH UNCERTAINTY. IN ORDER TO ACCOMMODATE THE ABOVE CONSIDERATIONS... AND ACCOUNTING FOR THE ECMWF COMPARING SOMEWHAT BETTER TO THE FULL ARRAY OF GUIDANCE THAN THE GFS... THE DAYS 3-7 MON-FRI FCST STARTS WITH A BLEND OF THE 00Z ECMWF AND GEFS/ECMWF ENSEMBLE MEANS. SLIGHTLY MORE WEIGHT WAS GIVEN TO THE ECMWF DAYS 3-4 BEFORE OPERATIONAL DETAILS BECOME MORE UNCERTAIN. WE SEE NO COMPELLING REASON TO ADJUST HPC CONTINUITY FOR OUR FINAL PRODUCTS CONSIDERING THE WIDE ARRAY OF FORECAST SOLUTIONS STILL PROVIDED BY LATEST 12 UTC MODELS AND ENSEMBLES. RAUSCH/SCHICHTEL $$