EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 234 AM EDT WED JUN 22 2016 VALID 12Z SAT JUN 25 2016 - 12Z WED JUN 29 2016 ...OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES... GUIDANCE CONTINUES TO DISPLAY UNUSUALLY GOOD AGREEMENT AND CONTINUITY WITH THE FCST LARGE SCALE EVOLUTION INTO THE MIDDLE OF NEXT WEEK. A VIGOROUS TROUGH WITH EMBEDDED UPR LOW WILL PROGRESS EWD FROM THE NRN ROCKIES/PLAINS... GRADUALLY BROADENING AS IT SETTLES INTO THE ERN NOAM MEAN TROUGH. BY THE LATTER HALF OF THE PERIOD THIS TROUGH MAY INTERACT WITH RETROGRADING WRN ATLC ENERGY THAT BEGINS TO SEPARATE FROM THE WESTERLIES DURING THE WEEKEND. AT THE SAME TIME THE FCST REMAINS ON TRACK FOR ANOTHER 594+DM RIDGE TO BUILD OVER THE SRN HALF OF THE WEST WHILE AN UPR LOW HOVERS OVER THE EXTREME NERN PAC. THERE ARE SOME MEDIUM TO SMALLER SCALE UNCERTAINTIES WITHIN THE CONSENSUS MEAN PATTERN. BY THE LATTER HALF OF THE PERIOD SHRTWV DETAILS WITHIN THE ERN TROUGH WILL INFLUENCE TIMING/WAVINESS OF THE LEADING SFC FRONT. SPECIFICS OF SHRTWV ENERGY EJECTING FROM THE ERN PAC AND THEN ROUNDING THE WRN RIDGE WILL BE IMPORTANT FOR THE FCST OF PLAINS CONVECTION LATE IN THE PERIOD. IN BOTH CASES THE SCALE IS SUFFICIENTLY SMALL TO PRECLUDE CONFIDENT SELECTION OF A PARTICULAR SOLN. FINALLY THERE HAS BEEN SOME SPREAD/VARIABILITY WITH THE DEGREE OF EWD PROGRESSION OF THE NERN PAC UPR LOW LATE IN THE PERIOD. THROUGH THE 12Z/18Z CYCLE THE 12Z ECMWF BECAME A LITTLE MORE PROGRESSIVE THAN MOST OTHER SOLNS BY DAY 7 WED THOUGH THE 18Z GFS BEGAN TO SHOW SOME EWD MOVEMENT AS WELL. LONGER TERM ECMWF TREND HAS BEEN SLOWER SO BY LATE IN THE PERIOD PREFER TO STAY CLOSER TO THE ENSEMBLE MEANS AND 12Z GFS. IN ADDITION TO NERN PAC/WRN NOAM CONSIDERATIONS OTHER DETAILS OF THE 12Z GFS COMPARED A LITTLE BETTER TO CONSENSUS THAN THE 18Z RUN SO THE UPDATED FCST PLACED MAJORITY EMPHASIS ON THE 12Z GFS/ECMWF DAYS 3-5 SAT-MON WITH INCREASING 18Z GEFS/12Z ECMWF ENSEMBLE MEAN WEIGHT BY DAYS 6-7 TUE-WED. LOWER CONFIDENCE IN THE 12Z ECMWF FCST OVER THE NERN PAC/WRN NOAM AND WITH ERN U.S. DETAILS BY DAY 7 WED LED TO KEEPING IT OUT OF THE BLEND FOR DAY 7. ...SENSIBLE WEATHER HIGHLIGHTS... COLD FRONT PUSHING ACROSS THE NRN TIER DURING THE WEEKEND MAY BE ACCOMPANIED BY SOME LOCALLY INTENSE RNFL AND STRONG TO SEVERE CONVECTION. CONSULT LATEST SPC OUTLOOKS FOR FURTHER INFO ON SEVERE THREATS. AREAS OF RAIN/TSTMS WILL EXTEND INTO THE EAST WITH TIME. TO THE E OF THE MS RIVER THE COMBINATION OF ONE OR MORE FRONTAL WAVES THROUGH THE PERIOD AND A PSBL DISSIPATION/REFORMING OF THE FRONT AROUND SUN-MON COULD AT TIMES SLOW DOWN FRONTAL PROGRESSION AND ALLOW FOR ENHANCED RNFL TOTALS. BY THE LATTER HALF OF THE PERIOD THE CNTRL PLAINS AND VICINITY MAY SEE AN INCREASE OF CONVECTION WITH THE COMBINATION OF THE TRAILING PART OF THE SFC FRONT REMAINING OVER THE REGION AND SHRTWV ENERGY COMING AROUND THE WRN RIDGE ALOFT. EXPECT DIURNALLY ENHANCED CONVECTION OVER THE SRN TIER WITH A GRADUALLY WEAKENING FRONT OVER THE SOUTHEAST PROVIDING A FOCUS DURING THE FIRST HALF OF THE PERIOD. THE REBUILDING OF THE WRN RIDGE WILL BRING ANOTHER PERIOD OF VERY HOT WEATHER TO THE WEST WITH PLUS 10F OR GREATER ANOMALIES FOR HIGHS LIKELY TO BECOME WIDESPREAD BY NEXT MON-WED WITH SOME DAILY RECORDS PSBL. ON THE OTHER HAND THE GRADUAL DEVELOPMENT OF AN ERN TROUGH SHOULD BRING TEMPS CLOSER TO NORMAL OVER THE SOUTHEAST BY MIDWEEK. BEFORE THAT OCCURS... FLOW AHEAD OF THE FRONT EMERGING FROM THE PLAINS WILL BRING ONE OR MORE DAYS OF VERY WARM TO HOT TEMPS INTO THE MIDWEST/NORTHEAST. COVERAGE OF BELOW NORMAL TEMPS WILL BE FAIRLY LIMITED... ACROSS THE EXTREME NRN TIER BEHIND THE FRONT AND IN PARTICULAR THE NRN HIGH PLAINS ON SAT... AND ALONG THE MID ATLC COAST DURING THE WEEKEND DUE TO ONSHORE FLOW. RAUSCH