EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1154 AM EDT THU APR 10 2014 VALID 12Z SUN APR 13 2014 - 12Z THU APR 17 2014 ...MAJOR SPRING STORM FROM THE ROCKIES TO THE EAST COAST... THE CONVERGENCE OF HIGHLY DISPARATE AIRMASSES OVER THE CENTRAL STATES SUNDAY AND MONDAY IS EXPECTED TO FOCUS AN EXTREMELY ENERGETIC COLD FRONT AND DRYLINE SYSTEM. ON THE COLD SIDE OF THE BAROCLINIC ZONE, GUSTY WINDS AND HEAVY UPSLOPE SNOWS ARE ANTICIPATED OVER THE CENTRAL AND NORTHERN ROCKIES AND CENTRAL HIGH PLAINS SUNDAY. SEVERE THUNDERSTORMS ARE LIKELY SUNDAY AFTERNOON INTO SUNDAY EVENING OVER THE SOUTHERN PLAINS INTO THE ARKLATEX, WHERE REMARKABLE DISCONTINUITIES ARE PROGGED ALONG THE SOUTHWARD-PLUNGING COLD FRONT AND PACIFIC-REINFORCED DRYLINE. AS THE SYSTEM EVOLVES EASTWARD SUNDAY NIGHT THROUGH TUESDAY, A GRADUAL SHIFT FROM SEVERE WEATHER TO WIDESPREAD HEAVY SHOWERS SHOULD MARK THE WARM SECTOR, WITH A NEW SWATH OF SNOW BLOOMING ACROSS THE UPPER MIDWEST AND GREAT LAKES. THE ENTIRE COMPLEX SHOULD HIT THE WALL OF THE WESTERN ATLANTIC RIDGE ASTRIDE THE APPALACHIANS EARLY TUESDAY--PRESERVING OR EVEN STRENGTHENING THE DISCONTINUOUS NATURE OF THE THEN MERIDIONALLY-ORIENTED COLD FRONT. USED RECENT OPERATIONAL ECMWF RUNS FOR THE DETAILS OF THIS SPRAWLING SYSTEM THROUGH TUESDAY MORNING DUE TO THAT MODEL'S STABILITY FOR THE PAST FEW CYCLES. BY WEDNESDAY AND THURSDAY, SWITCHED TO THE 00Z/10 ECENS MEAN--AS SUPPORTED BY THE NAEFS MEAN--AS GUIDANCE FOR THE FLOW IN THE WAKE OF THE BIG FRONT. ONE OF THE BIGGEST UNCERTAINTIES LATE TUESDAY INTO THURSDAY IS HOW MUCH MOISTURE AND FORCING REMAIN BEHIND THE FRONT OVER THE EAST. OF PARTICULAR CONCERN IS THE POSSIBILITY OF HEAVY LATE-SEASON SNOWFALL IN THE APPALACHIANS AND INTERIOR NORTHEAST IF THE WHOLE SYSTEM GETS HUNG UP JUST OFFSHORE. THE ONLY PART OF THE NATION SHELTERED FROM THE ENERGETIC PATTERN APPEARS TO BE THE SOUTHWEST. CISCO