EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 240 AM EDT SUN MAY 11 2014 VALID 12Z WED MAY 14 2014 - 12Z SUN MAY 18 2014 ...OVERVIEW AND PREFERENCES... THE FCST REMAINS FAIRLY WELL ON TRACK FOR THE BROAD AMPLIFIED TROUGH EXPECTED TO SETTLE OVER THE ERN HALF OF THE CONUS AS DOWNSTREAM ATLC FLOW BECOMES INCREASINGLY BLOCKY... WHILE GRADUAL OPENING UP/PROGRESSION OF ERN PAC CLOSED LOW ENERGY SHOULD EVENTUALLY NUDGE A STRONG WEST COAST RIDGE A LITTLE FARTHER INLAND. DURING THE FIRST HALF OF THE PERIOD GFS/GEFS RUNS CONTINUE TO BE ON THE FASTER EDGE OF THE GUIDANCE SPREAD WITH HGT FALLS ADVANCING THROUGH THE EAST. MULTI-DAY TRENDS/CONTINUITY AND AMPLITUDE OF THE EVOLVING PATTERN RECOMMEND THE 12Z ECMWF MEAN AND TO A SOMEWHAT LESSER EXTENT NAEFS MEAN/ECMWF FROM DAY 3 WED INTO DAY 5 FRI. AFTER FRI THE 12Z/18Z GEFS MEANS COMPARE BETTER TO OTHER SOLNS OVER THE EAST ALLOWING FOR SOME INCLUSION IN THE FCST... BUT SLOWER TRENDS IN ECMWF-BASED SOLNS WITH ERN PAC ENERGY HEADING TOWARD THE WEST COAST ARE SUFFICIENTLY REASONABLE TO FAVOR LEANING 2/3 TOWARD THE ECMWF MEAN FOR DAYS 6-7 SAT-SUN. ...GUIDANCE EVALUATION... SOLN SPREAD IS GRADUALLY NARROWING BUT GFS/GEFS SOLNS ARE CONTINUING TO BRING LEADING HGT FALLS INTO THE EAST FASTER THAN MOST OTHER GUIDANCE IN THE MID-LATE WEEK TIME FRAME. TRENDS AND CONTINUITY OVER MULTIPLE DAYS HAVE BEEN FAVORING SLOWER TIMING AS SUPPORTED BY THE AMPLIFIED NATURE OF THE PATTERN AND INCREASING BLOCKINESS OF DOWNSTREAM ATLC FLOW... SO SEE NO REASON TO DEVIATE FROM SOLNS IN THE SLOWER HALF OF THE SPREAD ASIDE FROM CMC RUNS THAT HAVE BEEN EXTREME RELATIVE TO MOST ENSEMBLES. A SMALL CONTRIBUTION OF THE OPERATIONAL 12Z ECMWF WAS INCLUDED WED-FRI IN LIGHT OF SOME NON-GFS MODELS SHOWING SOME SEPARATION OF ENERGY WITHIN THE OVERALL TROUGH. THE 00Z CMC STILL LOOKS TOO SLOW/AMPLIFIED BUT IT ALONG WITH THE 00Z UKMET ARE NOW LESS ENTHUSIASTIC ABOUT FLOW SEPARATION SO KEEPING 12Z ECMWF WEIGHTING FAIRLY LOW SEEMS REASONABLE. THERE IS STILL ROOM FOR SOME SEPARATION THOUGH. BY NEXT WEEKEND THE 12Z/18Z GEFS MEANS COMPARE BETTER TO THE ECMWF MEAN WITH THE CORE OF MID LVL ENERGY EXPECTED TO BE OVER OR NEAR THE GRTLKS. MOST OPERATIONAL RUNS COMPARE ACCEPTABLY TO THE CONSENSUS LARGE SCALE PATTERN BUT WITH DETAIL DIFFS THAT ARE TYPICALLY NOT WELL RESOLVED 6-7 DAYS OUT IN TIME. VERIFICATION AND BETTER STABILITY FAVOR THE ENSEMBLE MEANS FOR THIS PART OF THE FCST WITH THE UNDERSTANDING THAT THE UPR SYSTEM COULD END UP BEING SOMEWHAT DEEPER... WHICH COULD PUSH THE ASSOC SFC FRONT/MSTR FARTHER EWD-NEWD. ECMWF/ECMWF MEAN SOLNS OVER THE PAST DAY HAVE TRENDED SOMEWHAT SLOWER WITH ERN PAC TROUGH/CLOSED LOW ENERGY EXPECTED TO APPROACH/REACH THE WEST COAST BY NEXT WEEKEND BUT OTHER SOLNS HAVE THUS FAR NOT EXHIBITED SUCH TRENDS. RIDGING EXPECTED TO BUILD OVER THE SERN BERING SEA/SRN ALASKA FOR A PORTION OF THE PERIOD HAS THE POTENTIAL TO SLOW DOWN THE FEATURE TO THE S TEMPORARILY. THIS COMBINED WITH THE AMPLIFIED/BLOCKY PATTERN DOWNSTREAM... AND UKMET RUNS THAT ARE NO FASTER THAN A COMPROMISE TIMING INTO FRI... SEEM TO SUPPORT LEANING MORE TOWARD THE SLOWER ECMWF MEAN. ...SENSIBLE WEATHER HIGHLIGHTS... STRONG RIDGE ALOFT NEAR THE WEST COAST AS OF WED WILL SUPPORT VERY WARM TO HOT TEMPS WEST OF THE ROCKIES. NRN-CNTRL PARTS OF THE WEST SHOULD SEE A COOLING TREND AND A MODEST INCREASE IN MSTR BY NEXT WEEKEND AS THE RIDGE WEAKENS SOMEWHAT AND MOVES INLAND. EXPECT GREATEST COVERAGE OF PLUS 10-20F AND ISOLD HIGHER ANOMALIES NEAR THE WEST COAST WED-FRI WITH SOME DAILY RECORD HIGHS PSBL. THE WAVY SFC FRONT AHEAD OF THE TROUGH ALOFT SETTLING OVER THE EAST WILL BRING THE POTENTIAL FOR LOCALLY HVY RNFL TO AREAS FROM THE MS VLY TO EAST COAST. TWO FACTORS MAY COMBINE TO ENHANCE RNFL ALONG THE EAST COAST FROM THU ONWARD... INCORPORATION OF SOME MSTR AND SOME DEGREE OF MID LVL/SFC REFLECTION EMERGING FROM NEAR THE NRN CARIBBEAN AS WELL AS A BAND OF STRONG DEEP LAYER ATLC INFLOW MOVING FROM SRN TO NRN PARTS OF THE EAST COAST DURING THAT TIME FRAME. BEHIND THE FRONT ONE OR MORE IMPULSES WITHIN THE UPR TROUGH MAY GENERATE POCKETS OF RNFL WITH SOME DIURNAL ENHANCEMENT. FARTHER WWD EXPECT A BAND OF MSTR TO BECOME ESTABLISHED FOR A WHILE OVER THE NRN-CNTRL ROCKIES/HIGH PLAINS. THE LARGE SCALE PATTERN WILL MAINTAIN BELOW TO WELL BELOW NORMAL DAYTIME HIGHS OVER MUCH OF THE CNTRL-ERN CONUS. ONE OR MORE DAYS AT LEAST 10F BELOW NORMAL ARE MOST LIKELY FROM THE PLAINS INTO THE OH VLY/GRTLKS. RAUSCH