EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1200 PM EDT WED AUG 26 2015 VALID 12Z SAT AUG 29 2015 - 12Z WED SEP 02 2015 ...ERIKA FORECAST TO THREATEN FL AND VICINITY BY EARLY NEXT WEEK... ...PATTERN OVERVIEW AND GUIDANCE EVALUATION AND PREFERENCES... MODELS CONTINUE TO DEPICT A 500MB LONGWAVE TROUGH MOVING INTO THE WEST COAST AS A WARM HIGH GRADUALLY BUILDING EASTWARD ACROSS THE U.S. AND WITH A BREAK/WEAKNESS OF THE HIGH IN THE FORM OF A SHEAR AXIS LINGERING OVER THE CENTRAL GULF COAST. IN THE MEAN TIME...TROPICAL STORM ERIKA IS FORECAST TO INTENSIFY TO A HURRICANE AND MOVE OVER EASTERN FLORIDA EARLY NEXT WEEK. THE LARGEST MODEL DIFFERENCE IN THE MID-LATITUDES IS SEEN REGARDING THE WEST COAST UPPER-LEVEL TROUGH. PREVIOUS RUNS OF THE GEFS DEPICTED DEEPER AND HIGHER AMPLITUDE TROUGH THAN THE EC MEAN ON DAY 6/TUE AND DAY 7/WED. THE LATEST 00Z RUN OF THE EC MEAN TRENDED TOWARD A DEEPER SOLUTION. IN VIEW OF THIS...A GENERAL MODEL PROMISE IS USED GIVING EQUAL WEIGHTS TO BOTH THE 06Z GEFS MEAN AND THE 00Z EC MEAN THROUGH THE MEDIUM-RANGE PERIOD. AS FOR ERIKA...MODELS HAVE DEFINITELY TRENDED WESTWARD WITH RESPECT TO THE DAY 6 AND 7 POSITIONS. ERIKA IS TAKEN NORTHWARD ACROSS EASTERN FLORIDA AHEAD OF THE CENTRAL GULF COAST SHEAR AXIS FOLLOWING THE DAY 5 NHC FORECAST POSITION. ...SENSIBLE WEATHER HIGHLIGHTS... WITH THE APPROACH OF THE UPPER-LEVEL TROUGH...COOLER AIR IS EXPECTED TO SPREAD INLAND ACROSS THE PACIFIC NORTHWEST WHERE COOL DAYS AND MILD NIGHTS ARE FORECAST. RAIN IS FORECAST TO LINGER IN THE PACIFIC NORTHWEST WITH A GRADUAL DRYING TREND BY EARLY NEXT WEEK. WARMER AIR IS EXPECTED TO SPREAD EASTWARD ACROSS THE COUNTRY INTO EARLY NEXT WEEK AS ERIKA IS FORECAST TO MAKE LANDFALL OVER FLORIDA. RAINFALL AMOUNTS ARE RELATIVELY LIGHT OUTSIDE OF ERIKA. BUT A LINGERING FRONT ACROSS NORTHERN FLORIDA AND JUST OF THE SOUTHEAST COAST WILL ALLOW SHOWERS AND THUNDERSTORMS TO CONTINUE NEAR THE GULF COAST...FLORIDA...AND IN THE VICINITY OF THE SOUTHEAST U.S. COAST. KONG