EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 141 AM EDT SAT MAR 15 2014 VALID 12Z TUE MAR 18 2014 - 12Z SAT MAR 22 2014 ...ACTIVE/CHAOTIC AND TRANSITIONAL PATTERN... ...GUIDANCE/UNCERTAINTY ASSESSMENTS... PREFER A SIMILAR FORECAST STRATEGY AS YESTERDAY AND HAVE LEANED AWAY FROM CHAOTIC SHORT AND MEDIUM RANGE MODEL RUN TO RUN TRENDS. IT STILL SEEMS PRUDENT THAT GIVEN THE AMPLITUDE OF ENERGETIC PACIFIC SYSTEMS IN WATER VAPOR LOOPS AND GUIDANCE...PREFER A MID-UPPER LEVEL MEDIUM RANGE PATTERN EVOLUTION DOWNSTREAM OVER THE LOWER 48 THAT HIGHLIGHTS SYSTEMS ON THE AMPLIFIED AND SOMEHWAT LESS PROGRESSIVE SIDE OF THE FULL COMPOSITE ENVELOPE OF MODEL AND ENSEMBLE SOLUTIONS INTO MID-LATE NEXT WEEK WHEN TIMING DIFFERENCES ARE MOST EVIDENT. HOWEVER...REMAIN HESITANT TO EMBRACE THE MOST AMPLIFIED OUTLIER SOLUTIONS CONSIDERING RUN-RUN FLUCTUATIONS IN DETERMINISTIC MODELS AND ELEVATED FORECAST SPREAD/UNCERTAINTY WITH EMBEDDED SENSIBLE WEATHER FOCUSING SYSTEMS. WITH THESE PATTERN PREFERENCES IN MIND...WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS ALONG WITH HPCGUIDE SENSIBLE WEATHER GRIDS WERE PRIMARILY DERIVED FROM A BLEND OF REASONABLY COMPATABLE/CLUSTERED GUIDANCE FROM THE 12 UTC ECMWF/ECMWF ENSEMBLE MEAN/UKMET AND 18 UTC GFS ENSEMBLE MEAN DAYS 3/4 TUE/WED BEFORE SWITCHING INCREASINGLY OVER TIME FROM DAYS 5-7 THU-NEXT SAT TO THE ECMWF ENSEMBLE MEAN THAT MAINTAINS MAX PATTERN AND WPC CONTINUITY. ...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS... MID-UPPER LEVEL FLOW OFFERS LEAD REMAINING NRN AND SRN STREAM TROUGHING MOVING OFF THE EAST COAST TUE. DEEPEST MOISTURE/PCPN SHOULD LINGER OVER FL UNDERNEATH UNSEASONABLY COOLED HIGH PRESSURE TO THE NORTH IN THE WAKE OF SHORT RANGE WINTERY SYSTEM PASSAGE THAT ERODES BY MIDWEEK. THIS OCCURS AS AN UPSTREAM AND VIGOROUS WRN US MID-UPPER LEVEL COOLING TROUGH AND LEAD FRONTAL PUSH DIGS LOCALLY AND TERRAIN ENHANCED PCPN THROUGH THE N-CENTRAL INTERMOUNTAIN WEST/ROCKIES/PLAINS INTO TUE...CONTINUING ONWARD OVER THE CENTRAL THEN ERN US WED-FRI AIDED BY WELL ORGANIZED LATE WINTER CYCLOGENESIS ALLOWING SNOW SWATH POTENTIAL ON THE NRN PORTION OF THE LOW TRACK/PCPN SWATH AND A WARMING PRE-FRONTAL AIRMASS. FURTHER UPSTREAM...ANOTHER VIGOROUS AND MID-UPPER LEVEL TROUGH AND SURFACE SYSTEM PUNCHES PCPN THROUGH THE NWRN US AGAIN INTO THU...WITH SUBSEQUENT PROGRESSION OUT THROUGH THE WEST/ROCKIES IN FLATTER FLOW BY NEXT WEEKEND ACROSS THE CENTRAL AND ERN US. EXPECT MORE ROLLER COASTER WEATHER SHIFTS WITH LEAD WARMING/MODEST MOISTURE FOLLOWED BY THE DRAGGING OF SOME COLDER AIR DOWN IN THE WAKE OF THE ASSOCIATED WAVY FRONTAL SYSTEM. SCHICHTEL