EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1146 AM EDT THU JUN 02 2016 VALID 12Z SUN JUN 05 2016 - 12Z THU JUN 09 2016 ...WEATHER PATTERN HIGHLIGHTS/THREATS AND GUIDANCE/UNCERTAINTY ASSESSMENT... THE AVERAGE TO ABOVE AVERAGE MEDIUM RANGE PREDICTABILITY IDENTIFIED OVER THE PAST SEVERAL DAYS CONTINUES WITH A RELATIVELY ACTIVE EARLY JUNE PATTERN. A DEVELOPING RIDGE OVER THE WEST AND A TROUGH IN THE EAST CONTINUES TO DOMINATE THE FLOW REGIME ACROSS THE NATION WITH A POSSIBLE TROPICAL SYSTEM AFFECTING FLORIDA. SEE LATEST HURRICANE CENTER OUTLOOKS FOR ADDITIONAL DETAILS. AS THE FORECAST PROCEEDS INTO MID NEXT WEEK...TROUGHING WILL MAKE ITS WAY BACK ACROSS THE WESTERN AND NORTHWESTERN UNITED STATES. BY SUNDAY...THE START OF THE MEDIUM RANGE FORECAST PERIOD...A RATHER DEEP TROUGH OVER THE EASTERN US IS ALREADY ESTABLISHED WITH WIDESPREAD CHANCES FOR SIGNIFICANT PRECIPITATION ALONG THE EAST AND GULF COASTS. MEANWHILE... A PRONOUNCED RIDGE HAS EVOLVED OUT WEST ACCOMPANIED BY RECORD OR NEAR RECORD HEAT. WITHIN THE WESTERN RIDGE... A WEAK UPPER LOW CUT THROUGH THE RIDGE FROM CENTRAL CALIFORNIA INTO THE INTERMOUNTAIN WEST ON MONDAY INTO TUESDAY...INCREASING THE CHANCES FOR SCATTERED HIGH ELEVATION CONVECTION THROUGHOUT THE INTERMOUNTAIN WEST. BY EARLY NEXT WEEK...THE PRIMARY COLD FRONT HAS CLEARED THE EAST COAST BUT CYCLONIC FLOW WILL KEEP THE CHANCE FOR SHOWERS ACROSS THE US CANADIAN BORDER FROM THE UPPER MISSISSIPPI VALLEY ACROSS THE UPPER MIDWEST AND NORTHERN NORTHEAST WHILE EMBEDDED IMPULSES AROUND THE SIGNIFICANT EASTERN TROUGH WILL BRING SCATTERED SHOWERS AND POSSIBLE THUNDERSHOWERS WITH A STRONG DIURNAL COMPONENT ALONG THE RELATIVELY COOLER TEMPERATURES. A POSSIBLE TROPICAL LOW WILL DEVELOP IN THE EASTERN GULF OF MEXICO AND CURRENTLY APPEARS TO HEAD TOWARD WESTERN FLORIDA BY TUESDAY. THERE IS CONSIDERABLE UNCERTAINTY WITH THIS FEATURE BUT IT DOES HAVE THE POTENTIAL TO BRING HEAVY DOWNPOURS AND IS BEING MONITORED BY THE NATIONAL HURRICANE CENTER. BY MIDWEEK...HIGH PRESSURE BUILDS ACROSS MUCH OF THE EASTERN US WITH SHOWERS STILL POSSIBLE ACROSS THE MID ATLANTIC STATES INTO NEW ENGLAND AS THE UPPER TROUGH AXIS STILL REMAINS NEAR THE REGION ON WEDNESDAY. MEANWHILE...ANOTHER UPPER TROUGH IS EXPECTED TO MOVE ACROSS THE NORTHWEST WITH MUCH COOLER TEMPERATURES PROGRESSING EASTWARD AFTER THE WEEKEND HEAT. SOME RETURN SOUTHERLY FLOW FROM THE WESTERN GULF OF MEXICO BEHIND THE RETREATING HIGH PRESSURE SYSTEM AND DEVELOPING LOW PRESSURE ACROSS THE PLAINS COULD INCREASE THE CHANCES FOR SHOWERS AND THUNDERSTORMS AHEAD OF THE COLD FRONT MOVING ACROSS THE ROCKIES. THE GFS/ECMWF AND GEFS/ECMWF ENSEMBLE MEANS WERE USED TO GENERATE THE FORECAST AS BOT THE UKMET/CANADIAN SOLUTIONS APPEARED TO HAVE SOLUTIONS THAT SEEMED MORE OUTLIER THAN HIGHER PROBABILITY. THERE APPEARS TO BE A TREND TOWARD A FASTER SOLUTION OF THE NORTHWESTERN TROUGH LATER IN THE FORECAST WHEN COMPARED TO RECENT FORECASTS. KOCIN