EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1111 AM EDT TUE APR 19 2016 VALID 12Z FRI APR 22 2016 - 12Z TUE APR 26 2016 ...MODEL PREFERENCES... FOR DAYS 3-4 (TIL 24/00Z) ... A 19/00Z DETERMINISTIC-BASED GFS/ECMWF SOLUTION MIXED AND BLENDED WITH THEIR ENSEMBLE MEANS OFFERED THE BEST RESULTS WEST-TO-EAST ACROSS THE LOWER 48. AFTER 24/00Z --- USED CONTINUITY (THE PREVIOUS WPC CHOICES). ...UNCERTAINTY ASSESSMENT... MAIN FORECAST CHALLENGE APPEARS TO BE IN THE WEST. NOT ONLY WITH THE BULK OF THE MID-LEVEL (500MB) TROUGH MIGRATING EASTWARD TO THE CONTINENTAL DIVIDE THROUGH DAY 5 (25/00Z) --- BUT ALSO WITH THE TRAJECTORY OR TRAJECTORIES OF LEAD PACIFIC ENERGY BREAKING OFF DOWNSTREAM OVER THE PLAINS. STILL HAVE THE 19/00Z CANADIAN/GFS-BASED SOLUTIONS AT MID-POINT DAY 4 (23/12Z) THAT CARRY A CUTOFF AND TRAJECTORY ALONG THE LOWER COLORADO BASIN (CA/AZ BORDER). MEANWHILE THE 19/00Z UKMET/ECMWF-BASED SOLUTIONS --- HAVE THE CUTOFF INVOF EAST CENTRAL NEVADA. THESE VARIOUS SOLUTIONS AT MID-POINT DAY 5 (24/12Z) --- JUST 24 HOURS LATER-- PROPAGATE DOWNSTREAM TO EVEN GREATER DEPARTURES IN LATITUDE --- WITH THE LEAD ENERGY EITHER INVOF WYOMING (ECMWF/UKMET) OR AZ/NM BORDER (GFS/CANADIAN). SEEMS BETTER TO MAINTAIN CONTINUITY AFTER DAY 4 --- CARRYING OVER THE PREVIOUS WPC MASS FIELD PREFERENCES --- RATHER THAN 'RE-ASSEMBLE' A NEW MEDIUM RANGE SOLUTION 'FROM SCRATCH' --- THAT COULD CHANGE THE ENTIRE FORECAST OVER PORTIONS OF THE PLAINS (ALONG 100W). AND MORE IMPORTANTLY --- WOULD DO MORE DAMAGE THAN GOOD. ...SENSIBLE WEATHER HIGHLIGHTS... DURING THE LATTER HALF OF THE MEDIUM RANGE --- COOLER NIGHTS IN THE PACIFIC NORTHWEST/NORTHERN NEW ENGLAND --- AND A WARMING TREND FOR DAYTIME HIGHS ACROSS THE SOUTHERN PLAINS AND SOUTHEAST. VOJTESAK