EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 205 AM EDT THU MAY 07 2015 VALID 12Z SUN MAY 10 2015 - 12Z THU MAY 14 2015 ...OVERVIEW... UPPER RIDGING IS FORECAST TO LARGELY REMAIN IN PLACE OVER WESTERN CANADA WHICH FAVORS TROUGHING ALONG THE WEST COAST AND EVENTUALLY INTO THE NORTHEAST. OFF THE CAROLINA COAST... A POTENTIALLY-SUBTROPICAL LOW PRESSURE SHOULD SLOWLY LIFT NORTHEASTWARD SUN/MON ONCE IT GETS A NUDGE FROM THE FLOW UPSTREAM. ...MODEL/ENSEMBLE PREFERENCES... DECENT AGREEMENT STILL EXISTS OUT TO NEXT THURSDAY... MORE OR LESS... AMONG THE GUIDANCE... LIKELY OWING TO A FAIRLY AMPLIFIED FLOW THAT IS NEITHER TOO ZONAL OR OVERLY BLOCKY. FOR THE SE LOW... THE GFS/GEFS MEMBERS CONTINUE TO FALL ON THE SW SIDE OF THE SPREAD WHILE THE ECMWF AND ITS ENSEMBLES LIE TO THE NE SUN/MON THROUGH NC /OR SC IF THE GFS IS RIGHT/. FOLLOWING FROM COORDINATION ON WED AFTERNOON... PREFERENCE FOR THE MORE NORTHEASTERLY TRACK -- LIKE THE ECMWF -- WAS PREFERRED. BACK TO THE WEST... INCOMING UPPER LOW OFF THE OREGON COAST BY MONDAY SHOULD DIG SOUTHWARD IN RESPONSE TO NOW STRONGER RIDGING MAINTAINING ITSELF OVER ALBERTA. THIS WAS PROBABLY THE BIGGEST CHANGE IN THE FORECAST OVER THE PAST 24 HRS. WITHOUT A REAL PUSH EASTWARD OF THIS RIDGE... ENERGY IN THE NE PACIFIC SHOULD THEN DIG THROUGH THE WESTERN OR SW CONUS FOR PERHAPS THE THIRD TIME IN ABOUT A WEEK. FINALLY... MIDWEEK NEXT WEEK IN THE EAST... FRONT SHOULD PASS OFF THE COAST EARLY WEDNESDAY -- THIS TIMING HAS BEEN FAIRLY CONSISTENT -- BUT LINGER ALONG THE NORTHERN GULF COAST. SWITCHED THE BLEND OF THE ECMWF/ECENS MEAN FOR SUN-WED TO THE 12Z GEFS/ECENS MEAN BY NEXT THURSDAY... WHEN THE DETAILS OFF THE WEST COAST AND INTO THE PAC NW ITSELF BECOME MUDDLED. ...SENSIBLE WEATHER HIGHLIGHTS... TEMPERATURES ARE FORECAST TO BE WARMER THAN AVERAGE... ESPECIALLY FOR AM MIN TEMPS... AHEAD OF THE FRONT IN THE EAST EARLY IN THE PERIOD. TROUGHING IN THE WEST WILL KEEP MAX TEMPS NEAR/BELOW CLIMO. PRECIPITATION WILL FOCUS AROUND AND DOWNSTREAM OF THE EXITING CLOSED LOW FROM THE FRONT RANGE ON SUNDAY... WHERE SIGNIFICANT ACCUMULATING SNOW IS LOOKING MORE AND MORE LIKELY IN SOME PLACES LIKE SE WYOMING AND NW NEBRASKA. DAYTIME MAX TEMPS HERE WILL BE WELL BELOW AVERAGE ON THE ORDER OF 20-35F. ENSEMBLES CONTINUE TO SHOW SOUTH TEXAS IN A QPF MAX NEXT TUE-THU ALONG AND NORTH OF THE STALLED FRONTAL BOUNDARY. MEAN QPF NEARING TWO INCHES IN 48 HOURS IS NOT ALL THAT RARE TO SEE... BUT SOME MODEL QPFS -- E.G. THE 18Z GFS -- SHOW ABOUT 11 INCHES OF RAIN. OTHERS ARE MORE 'REASONABLE' IN THE 2-4 INCH RANGE. FRACASSO