EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1200 PM EDT TUE APR 01 2014 VALID 12Z FRI APR 04 2014 - 12Z TUE APR 08 2014 ...STORMY PATTERN...GUIDANCE/UNCERTAINTY ASSESSMENT...SENSIBLE WEATHER HIGHLIGHTS... WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS HAVE BEEN PRIMARILY DERIVED FROM A COMPOSITE BLEND OF THE 00 UTC GFS/ECMWF/CANADIAN DAYS DAYS 3/4 FRI/SAT. WHILE FORECAST SPREAD IS A BIT HIGHER THAN NORMAL...THESE 00 UTC GUIDANCE PIECES OFFER SYSTEM TIMINGS THAT ARE BETTER CLUSTERED THAN MORE PROGRESSIVE GUIDANCE FROM THE NAM/UKMET WITH A POTENT MID-UPPER LEVEL TROUGH AND ASSOCIATED SURFACE SYSTEM SLATED TO TRACK NEWD FROM THE MS VALLEY THRU THE GREAT LAKES/NORTHEAST ALONG WITH A GOOD SWATH OF PCPN INCLUDING NRN TIER SNOWS. UPSTREAM...EMERGING SPLIT FLOW INTO NOAM SEEMS WELL SHOWN IN MOST GUIDANCE WITH MID-UPPER LEVEL TROUGH APPROACH PASSAGE ACROSS THE NWRN US AND ESPECIALLY CA AND THE SWRN US DURING THIS PERIOD. OVERALLL...THIS MAINTAINS CLOSE WPC CONTINUITY WITH OVERNIGHT WPC SHORT RANGE PMDHMD PREFERENCES AND SEEMS REASONABLE CONSIDERING EMBEDDED SYSTEM STRENGTH AND KNOWN MODEL BIASES. WITH DETERMINISTIC MODELS OFFERING LESS THAN STELLAR RUN TO RUN CONTINUITY AT LONGER TIME FRAMES...PREFER TO TRANSITION SUN INTO A 50-50 BLEND OF THE 06 UTC GEFS MEAN/00 UTC ECMWF ENSEMBLE MEAN BY DAYS 6/7 NEXT MON/TUE. EVEN SO...THESE ENSEMBLE MEANS OFFER GREATER THAN NORMAL FORECAST SPREAD OVER THE E-CENTRAL US IN A POTENTIALLY QUITE CHAOTIC AND STORMY/WET PATTERN. HOWEVER...THEIR SOLUTIONS HAVE AT LEAST TRENDED TOWARD A MORE COMPATABLE SOLUTION WITH THEIR LATEST RESPECTIVE RENDITIONS. MANUAL FORECASTER ADJUSTMENTS SOLIDIFIED A THREAT FOR DYNAMIC LOW/FRONTAL SYSTEM DEVELOPMENT OVER THE E-CENTRAL US EARLY NEXT WEEK THAT WOULD HAVE THE POTENTIAL TO ADVECT IN DEEP LAYERED GULF AND ATLANTIC MOISTURE TO FUEL HEAVY WARM SECTOR/FRONTAL CONVECTIVE RAINFALL ALONG WITH LATE SEASON ORGANIZED SNOWS ON THE NW/NRN TIERS OF THE OVERALL PRECIPITATION SHIELD ACROSS THE MIDWEST/NORTHEAST IN A LINGERING COLDER AIRMASS. THIS OVERALL PATTERN PREFERENCE SEEMS REASONABLE CONSIDERING MOST GUIDANCE BUILDS QUITE A AMPLIFIED AND WARMING MID-UPPER LEVEL RIDGE UPSTREAM OVER WRN NORTH AMERICA AND SIGNIFICANT ENERGIES SPLIT INTO DISTINCT NRN AND ESPECIALLY SRN STREAM FLOWS. SCHICHTEL