000 FXUS02 KWBC 061806 PMDEPD EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 206 PM EDT MON JUL 06 2009 VALID 12Z THU JUL 09 2009 - 12Z MON JUL 13 2009 TODAYS OPERATIONAL MODEL AND ENSEMBLE GUIDANCE DISPLAYS BETTER THAN AVERAGE CLUSTERING WITH THE EXPECTED LARGE SCALE FLOW DURING THE FCST PERIOD. PRIMARY FCST ISSUES REVOLVE AROUND DETAILS WITHIN THE AGREED UPON MEAN FLOW THAT CONSISTS OF A STABLE SRN PLAINS-ROCKIES RIDGE ALONG WITH A PAC NW COAST TROF AND RELOADING ERN NOAM TROF. FOR THE IMPORTANT DETAILS THE LATEST ECMWF GUIDANCE... WHICH HAS BEEN FAIRLY CONSISTENT WITH THE FLOW PATTERN FOR SEVERAL DAYS... PROVIDES A MORE REASONABLE FCST RELATIVE TO THE OVERALL ARRAY OF MODEL/ENSEMBLE SOLNS VERSUS THE LATEST GFS RUNS. THUS THE FCST IS BASED MOSTLY UPON THE 00Z ECMWF/ECMWF ENSEMBLE MEAN SOLNS. TELECONNECTIONS RELATIVE TO A CORE OF POSITIVE ANOMALIES JUST OFF THE SERN ALASKA COAST OFFER GOOD SUPPORT FOR THE TROF FCST TO PERSIST NEAR THE PAC NW COAST FOR MOST OF THE PERIOD. SOME EWD EJECTION IS POSSIBLE BY SUN-MON BUT THE 00Z/06Z GFS RUNS LEAN ON THE FAST EDGE OF THE GEFS/ECMWF/CMC ENSEMBLE SPREAD. A BLEND OF THE 00Z ECMWF AND SLIGHTLY SLOWER ENSEMBLE MEANS PROVIDES A REASONABLE BALANCE TO ACCOUNT FOR THE POSSIBILITY THAT SOME UPSTREAM ENERGY MAY BEGIN TO EJECT THE TROF LATE IN THE PERIOD VERSUS THE TENDENCY FOR FASTER EJECTING SOLNS WITHIN AN AMPLIFIED PATTERN TO BE INCORRECT. FARTHER EWD... CNTRL CANADA ENERGY IS FCST TO CONSOLIDATE AND SUPPORT STRONG LOW PRESSURE WELL N OF THE CONUS. THIS ENERGY SHOULD GRADUALLY RELOAD THE PERSISTENT ERN NOAM MEAN TROF AFTER A BRIEF RISE IN ERN CONUS HGTS LATE THIS WEEK. THIS RELOADING WOULD BE CONSISTENT WITH TELECONNECTION FAVORED ERN CONUS/SERN CANADA TROFFING ASSOC WITH A DECENT CORE OF POSITIVE HGT ANOMALIES WHICH MULTI-DAY MEANS SHOW OVER OR NEAR NERN CANADA. ALONG THE LEADING EDGE OF HGT FALLS SAT-MON... THERE IS MINIMAL SUPPORT FOR THE STRONG 00Z GFS FEEDBACK-AIDED SYSTEM TRACKING FROM THE PLAINS THRU THE NORTHEAST. THE 06Z GFS HAS TRENDED WEAKER BUT MAY STILL BE TOO FAST/STRONG BASED ON THE DOMINANT CLUSTERING OF ENSEMBLE SOLNS. AHEAD OF THESE FEATURES... THE BEST CONSENSUS OF MODELS AND GEFS/ECMWF ENSEMBLE MEANS SUGGESTS THE 00Z/06Z GFS RUNS MAY BE TOO FAR SEWD WITH THE MID LVL SYSTEM WHICH THE MODEL BRINGS ACROSS ONTARIO ON DAY 4 FRI... AND THAT THE GFS MAY BE TOO FLAT/PROGRESSIVE WITH THE TROF FCST TO BE OVER THE NORTHEAST AS OF DAY 3 THU. 12Z UPDATE... THE 12Z GFS BECOMES MORE PROGRESSIVE THAN THE PREVAILING CONSENSUS OF OTHER 12Z AND EARLIER GUIDANCE... INCLUDING THE 12Z GEFS MEAN... WITH NEARLY ALL FEATURES FROM THE NRN PACIFIC EWD ACROSS THE NRN CONUS AND SRN CANADA. THE ONE FAVORABLE TREND IN THE 12Z GFS IS TOWARD A WEAKER SFC PATTERN FROM THE PLAINS TO THE NORTHEAST WHERE EARLIER GFS RUNS HAD BEEN QUESTIONABLY STRONG BY SUN. OVERALL THERE IS NO COMPELLING REASON TO ALTER PRIOR FCST THINKING. THE ABOVE EVALUATION OF GUIDANCE LEADS TO FAVORING A SOLN CLOSE TO THE 00Z ECMWF FOR DAY 3 THU WITH INCREASED INCLUSION OF THE 00Z ECMWF ENSEMBLE MEAN THEREAFTER SO THAT DAYS 5-7 SAT-MON ACHIEVE A 50/50 WEIGHTING OF THE MODEL/ENSEMBLE MEAN SOLNS. MINOR ADJUSTMENTS WERE MADE OVER CNTRL CANADA TO ACCOUNT FOR AVERAGE OF OTHER GUIDANCE THAT IS A LITTLE WEAKER/EWD THAN THE OPERATIONAL ECMWF WITH DEEP LOW PRESSURE OVER THAT AREA. REGIONAL HIGHLIGHTS... ...WEST... EXPECT SCATTERED DIURNAL CONVECTION FROM THE FOUR CORNERS REGION INTO THE NORTHWEST... WITH THE BEST ORGANIZED ACTIVITY LIKELY TO BE OVER THE PAC NW/NRN ROCKIES ALONG AND AHEAD OF A PERSISTENT TROF ALOFT. DAYTIME TEMPS SHOULD BE VARIABLE OVER NRN AREAS WITH A WARMING TREND FOLLOWED BY A COOLING TREND. THE FOUR CORNERS REGION SHOULD SEE ABOVE NORMAL TEMPS ON AVERAGE WHILE DEPARTURES FROM NORMAL OVER THE WRN GRTBASIN/SOUTHWEST/CA WILL DISPLAY MORE LOCAL DEPENDENCE. ...CENTRAL/EAST... A PERSISTENT STRONG RIDGE ALOFT WILL KEEP HOT WEATHER OVER THE SRN PLAINS INTO THE SRN HALF OF THE MS VALLEY. DAYTIME HIGHS MAY REACH 10-12 F ABOVE NORMAL OVER PORTIONS OF THE S-CNTRL PLAINS... WHICH MAY APPROACH RECORD VALUES AT SOME LOCATIONS. NEAR TO SLIGHTLY ABOVE TEMPS SHOULD PREVAIL OVER THE SOUTHEAST. COLD FRONTAL PASSAGES SHOULD BE CONFINED TO THE NRN HALF OF THE CNTRL-ERN STATES. THIS PROGRESSION OF NRN CONUS SYSTEMS SHOULD ALLOW FOR AT LEAST A BRIEF PERIOD OF WARMER THAN AVERAGE READINGS AT MANY LOCATIONS THAT HAVE SEEN UNSEASONABLY COOL WEATHER RECENTLY... BUT NEAR TO BELOW NORMAL READINGS SHOULD RETURN TO THE NRN HALF OF THE CNTRL-ERN STATES BY EARLY NEXT WEEK. BEST ORGANIZED RNFL SHOULD BE ASSOC WITH THE FRONTAL SYSTEMS OVER THE NRN HALF OF THE CONUS AND WITH DIURNAL CONVECTION OVER THE SOUTHEAST/FL. RAUSCH/CISCO %$$