EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1148 AM EDT TUE MAY 05 2015 VALID 12Z FRI MAY 08 2015 - 12Z TUE MAY 12 2015 ...OVERVIEW AND GUIDANCE PREFERENCES... HAVE NOT DEVIATED SIGNIFICANTLY FROM LAST NIGHTS FORECAST PACKAGE. ACROSS THE NORTHEAST CORNER OF THE NATION...RIDGING WILL DOMINATE THE EARLY FLOW PATTERN. THE COMBINATION OF RIDGING IN THE NORTHEAST AND ACROSS NORTHWESTERN CANADA TELECONNECTS WITH TROUGHING OVER THE WESTERN US...WHICH WILL BE THE DOMINANT FLOW MODE BEGINNING THE MEDIUM RANGE...WHICH THEN PROGRESSES EASTWARD. WITHIN THE EASTERN RIDGE...A SUBTROPICAL LOW IS EXPECTED TO DEVELOP WITHIN THE EAST SOUTHEASTERLY FLOW OFF THE SOUTHEAST COAST IN THE SHORT RANGE AND THEN THEN CONTINUE SLOWLY WESTWARD IN THE MEDIUM RANGE. IN CONSULT WITH NHC...THIS LOW IS DEPICTED SO FAR AS A RELATIVELY WEAK SYSTEM THAT WILL MOVE SLOWLY WESTWARD POSSIBLY REACHING THE GEORGIA/SOUTH CAROLINA COAST BY AROUND SUNDAY TO MONDAY. THIS EARLY SEASON SYSTEM IS THE FIRST POTENTIAL TROPICAL SYSTEM OF THE SEASON. THERE IS GENERALLY DECENT AGREEMENT AMONG THE MODELS ON DAYS 3 TO 5/FRIDAY THROUGH SUNDAY DISCOUNTING THE OPERATIONAL CANADIAN. WHILE THE EUROPEAN ENSEMBLE MEANS SEEM TO HAVE SLIGHTLY MORE CYCLE TO CYCLE CONTINUITY WITH THE EVOLUTION OF FEATURES AFFECTING THE US...THERE ARE SOME SIGNIFICANT DIFFERENCES THAT BEGIN TO EMERGE DURING LATE WEEKEND INTO EARLY NEXT WEEK. THE MAIN CONCERN IS THAT THERE ARE A SIGNIFICANT NUMBER OF INDIVIDUAL ENSEMBLE RUNS THAT ARE SUGGESTIVE THAT ARE AT ODDS WITH THE EXTEND OF THE RESULTANT RIDGING OCCURRING AGAIN OVER THE NORTHEAST AND SOUTHEAST CANADA LATE IN THE FORECAST ON DAYS 6 AND 7...WHICH WOULD IMPLY A SIGNIFICANT WARMUP FOR THE NORTHEAST EARLY NEXT WEEK. HOWEVER...SOME OTHER MEMBERS ARE MORE SUGGESTIVE OF A FLATTER SOLUTION WITHIN CONFLUENT FLOW...ALLOWING COOLER AIR TO SUBSIDE INTO THE NORTHEAST. SOME OF LAST WEEKS FORECASTS INDICATED A WARM WEEK FOR MUCH OF THE EAST BUT AS THIS WEEK CONTINUES...COOLER AIR IS LIKELY TO FLOW SOUTHWARD ALONG THE EAST COAST. THIS CONTINUES TO BE A SIMILAR KIND OF DILEMMA FOR THE FORECAST FOR EARLY NEXT WEEK AS WELL. NOT MUCH CONFIDENCE EITHER WAY AT THIS POINT BUT FAVORED A MIXED SOLUTION LATE IN THE FORECAST...BUT NOT AS WARM AS THE EUROPEAN ENSEMBLES MAY HAVE INDICATED. TIME WILL TELL. IN ADDITION...RECENT OPERATIONAL GFS SOLUTIONS APPEAR TO BE ON THE EDGE OF THE SOLUTION ENVELOP IN THE EASTERN PACIFIC LATE IN THE FORECAST...SO HAVE MINIMIZED THEIR INFLUENCE. ...SENSIBLE WEATHER HIGHLIGHTS... TEMPERATURE DEPARTURES APPEAR COOLER THAN AVERAGE IN THE WEST AND WARMER THAN AVERAGE IN THE EAST. THE CENTRAL STATES WILL COOL DOWN BY EARLY NEXT WEEK AND ALLOW THE WEST TO REBOUND TO NEAR OR ABOVE AVERAGE. PRECIPITATION WILL FOCUS ALONG AND DOWNSTREAM OF THE CLOSED LOW THAT LIFTS FROM THE GREAT BASIN AND CENTRAL ROCKIES INTO THE CENTRAL/SOUTHERN PLAINS AND INTO THE GREAT LAKES. THE THREAT OF SEVERE WEATHER IS LIKELY TO BE SIGNIFICANT IN THE WARM SECTOR OF THIS SYSTEM AS IT PROGRESSES EASTWARD. IT DOES APPEAR THAT PRECIPITATION WITH THE SUBTROPICAL SYSTEM OFF THE SOUTHEAST COAST COULD MAKE ITS INFLUENCE KNOW OVER THE WEEKEND ON SATURDAY AND SUNDAY WITH THE BULK OF THE PRECIPITATION REMAINING OFFSHORE. AS THIS SYSTEM COULD COME ASHORE EARLY NEXT WEEK...PRECIPITATION WILL INCREASE ACROSS THE SOUTHEAST BUT CONFIDENCE IS RELATIVELY LOW GIVEN WHETHER IT WILL REMAIN WEAK OR POSSIBLY NOT COME ASHORE. BECAUSE OF THE CONCERNS OF THE RELATIVE EFFECTS OF RIDGING IN THE EAST VERSUS FLATTER MORE CONFLUENT FLOW...TEMPERATURE DEPARTURE FORECASTS ACROSS THE NORTHEASTERN CORNER OF THE NATION WILL HAVE LOW CONFIDENCE DUE TO CONCERNS ABOUT WHERE A BACKDOOR TYPE FRONT MOVES ON MONDAY AND TUESDAY. KOCIN