EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1215 PM EDT FRI AUG 04 2017 VALID 12Z MON AUG 07 2017 - 12Z FRI AUG 11 2017 ...PATTERN OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES... THE PERSISTENT PATTERN OF BROAD TROUGHING OVER MUCH OF THE CENTRAL AND EASTERN U.S. AND AN UPSTREAM RIDGE OVER THE NORTHWEST/WESTERN CANADA WILL CONTINUE THROUGH THE END OF NEXT WEEK, WITH THE MEAN RIDGE AXIS EXPECTED TO GRADUALLY SHIFT EASTWARD AS A DEEP VORTEX SOUTH OF ALASKA EDGES TOWARDS WESTERN CANADA DURING THE LATER HALF OF NEXT WEEK. MODELS REMAINED FAIRLY LOCKED INTO THE LONGWAVE PATTERN OVER THE LOWER 48 AND ARE EVEN STARTING TO COME INTO BETTER AGREEMENT WITH SHORTWAVES DIGGING INTO THE BROAD TROUGH OVER THE CENTRAL AND EASTERN U.S.. SPECIFICALLY, MODEL SOLUTIONS ARE FINALLY STARTING TO CONVERGE WITH AN INITIAL SHORTWAVE AND SURFACE LOW EXPECTED TO LIFT FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST MONDAY INTO TUESDAY. ON THE FLIP SIDE, MODEL GUIDANCE CONTINUES TO SHOW A WIDE RANGE OF SOLUTIONS WITH AN AREA OF DISTURBED WEATHER CURRENTLY BEING MONITORED BY THE NATIONAL HURRICANE CENTER, WHICH IS EXPECTED TO MOVE WEST-NORTHWESTWARD ACROSS THE WESTERN CARIBBEAN AND TOWARDS THE BAY OF CAMPECHE NEXT WEEK. THE WPC DAY 3-7 FORECAST STARTED WITH A BLEND BETWEEN GFS/ECMWF/CMC/GEFS MEAN/ECWMF ENSEMBLE MEAN/CONTINUITY, WITH LESS THAN AVERAGE WEIGHT GIVEN TOWARDS THE ECWMF SINCE THE 00Z RUN WAS ON THE STRONGER/NORTHERN SIDE OF MODEL SPREAD WITH THE SURFACE WAVE LIFTING FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST MONDAY INTO TUESDAY. THE 00Z ECMWF ALSO TOOK A BIG SHIFT FROM ITS PREVIOUS RUN WITH THE EVOLUTION OF THE LARGE UPPER VORTEX SOUTH OF ALASKA AND NOW APPEARS TO AN OUTLIER SOLUTION COMPARED TO THE GFS/GEFS MEAN/ECMWF ENSEMBLE MEAN. FINALLY, THE ECMWF CONTINUED TO OFFER ONE OF THE STRONGEST SOLUTIONS WITH THE POSSIBLE DEVELOPMENT OF A TROPICAL SYSTEM IN THE BAY OF CAMPECHE NEXT WEEK, BUT PLEASE REFER TO THE NATIONAL HURRICANE CENTER FOR THE LATEST INFORMATION ON THIS FEATURE. ...WEATHER HIGHLIGHTS... MODERATE TO HEAVY RAINFALL WILL BE POSSIBLE WITH A SURFACE WAVE AND TRAILING FRONTAL BOUNDARY PROGRESSING FROM THE OHIO VALLEY TO NEW ENGLAND NEXT MONDAY INTO TUESDAY. THE SURFACE WAVE AND COLD FRONT SHOULD BE QUICK TO EXIT THE NORTHEAST ON TUESDAY, BUT THE CHANCE FOR HEAVY RAINFALL WILL CONTINUE ALONG THE TAIL END OF THE BOUNDARY AS IT STALLS AND LINGERS ACROSS THE SOUTHERN TIER OF THE NATION THROUGH MUCH OF NEXT WEEK. FARTHER NORTH, SCATTERED PRECIPITATION WILL BE POSSIBLE WITH A COLD FRONT DROPPING THROUGH THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY. TEMPERATURES WILL REMAIN BELOW NORMAL BENEATH BROAD TROUGHING OVER THE CENTRAL AND EASTERN U.S., WHILE ABOVE NORMAL TEMPERATURES WILL PERSIST OVER THE NORTHWEST AND NORTHERN ROCKIES. GERHARDT