EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 108 AM EDT MON APR 13 2015 VALID 12Z THU APR 16 2015 - 12Z MON APR 20 2015 THE GEFS AND MSC ENSEMBLE MEMBERS CONTINUE TO BE MORE EMPHATIC ABOUT A LOW ALONG THE ATLANTIC SEABOARD DAYS 4 AND 5 THAN THE ECENS MEMBERS, THOUGH THE 12Z/12 EUROPEAN CENTRE GUIDANCE WAS MARKED BY MORE SUCH SOLUTIONS THAN PREVIOUS DATA CYCLES. THE CONSISTENCY IN THE NAEFS AND THE UPTICK IN THE ECENS WITH REGARD TO THE RESOLUTION OF AN EAST COAST LOW BUBBLING NORTHWARD DAY 4 WERE THE MAIN SUPPORTS IN RELYING ON THE NAEFS MEAN THIS FORECAST PACKAGE. AS IT IS, THE NAEFS MEAN IS NOT AN EASY ARITHMETIC AVERAGE OF SOLUTIONS FROM WHICH TO DIVINE FEATURES OF THE REAL ATMOSPHERE, AS IT IS COMPROMISED OF TWO DISTINCT FORECAST CENTER "TEMPERAMENTS"--DYNAMICS, PHYSICS, ET CETERA. BLENDING THE ECENS MEAN WITH THE NAEFS USUALLY RENDERS NULL ALL SEMBLANCE OF METEOROLOGICAL VERITY TO FRONTAL STRUCTURE, SO DID NOT ATTEMPT TO FURTHER MUDDLE THE ALREADY TENUOUS MANUAL PRESENTATION OF THE PROGRESSION OF SYSTEMS ACROSS THE NATION AT THE MEDIUM RANGE. WHAT CAN BE GLEANED FROM THE ONGOING DISPARATE SOLUTIONS IS THAT THE SHORTWAVE ENERGY TRAVERSING THE WELL-PRONOUNCED SPLIT FLOW OVER EAST-CENTRAL NORTH AMERICA DAYS 3 THROUGH 5 IS LIKELY TO INTERACT IN THE VICINITY OF THE MID-ATLANTIC AND NORTHEASTERN UNITED STATES COAST, SPREADING SOME OF THE JUICIER RAINFALL FROM THE GULF STATES INTO THOSE REGIONS. THE TAIL END OF THE NORTHERN STREAM SHORTWAVE SHOULD FOCUS SOME UPSLOPE PRECIPITATION OVER THE CENTRAL HIGH PLAINS LATE THIS WEEK. BY LATE IN THE WEEKEND INTO EARLY NEXT WEEK, A NEW WAVE PACKET SHOULD BE TAPPING THE GULF OF MEXICO ONCE AGAIN--THOUGH NOT AS VIGOROUSLY AS THE SYSTEM EARLY IN THE PERIOD. CISCO