EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1059 AM EST TUE FEB 11 2014 VALID 12Z FRI FEB 14 2014 - 12Z TUE FEB 18 2014 ...OVERVIEW AND PREFERENCES... MODELS/ENSEMBLES SHOW A FAIRLY LOW AMPLITUDE/PROGRESSIVE PATTERN DOWNSTREAM FROM A NERN PAC MEAN TROUGH. THIS WILL PROVIDE A WET REGIME OVER THE NRN HALF OF THE WEST COAST IN PARTICULAR... WITH MULTIPLE WAVES CONTINUING FARTHER EWD WITH SOME ACCOMPANYING PCPN. WHILE THERE IS SOME AGREEMENT ON THE EXISTENCE OF INDIVIDUAL FEATURES... THERE IS AT LEAST MODERATE SPREAD WITH THE SPECIFICS AND IT WILL LIKELY TAKE SOME TIME FOR SUCH DETAILS TO GET RESOLVED. IN COMBINING THE BEST IDEAS OF CONTINUITY AND LATEST GUIDANCE THE PREFERRED FCST STARTS WITH A COMPROMISE BETWEEN THE 00Z ECMWF AND 00Z/06Z GFS ON DAY 3 FRI... A 00Z ECMWF/ECMWF MEAN BLEND DAYS 4-6 SAT-MON... AND EXCLUSIVELY THE 00Z ECMWF MEAN DAY 7 TUE. ...GUIDANCE EVALUATION... CONSULT THE MODEL DIAGNOSTIC DISCUSSION FOR SHORT RANGE DIFFS/PREFS REGARDING THE MAJOR STORM EXPECTED TO AFFECT AREAS NEAR THE EAST COAST. BY 12Z FRI THE 00Z ECMWF/00Z-06Z GFS FORM A FAIR CONSENSUS WITH THIS SYSTEM. RIGHT BEHIND THIS STORM ANOTHER SYSTEM IS FCST TO TRACK FROM THE GRTLKS AND OFF THE NERN COAST FRI-SAT. BY EARLY SAT THE 06Z GEFS/00Z NAEFS MEANS OFFER BEST SUPPORT FOR THE 00Z ECMWF/ECMWF MEAN WHILE THE 06Z GFS BECOMES FAST ONCE OFFSHORE. NEXT IN CHRONOLOGICAL ORDER... SYSTEM REACHING THE PAC NW/BC ON FRI SHOULD REACH THE NRN PLAINS SAT AND ERN STATES BY SUN. THERE IS QUITE A BIT OF SPREAD ESPECIALLY BY SUN WITH 00Z/06Z GFS RUNS GENERALLY ON THE NRN OR NERN SIDE OF THE GUIDANCE ENVELOPE. THE PAST THREE ECMWF RUNS AND TWO ECMWF MEAN RUNS HAVE BEEN FAIRLY STEADY IN DEPICTING A FAIRLY SUPPRESSED WAVE RELATIVE TO SOMEWHAT MORE ERRATIC GFS RUNS. GEFS MEANS HAVE YET TO HOLD ONTO THIS WAVE TO THE E OF THE PLAINS. BROADNESS OF THE MEAN TROUGH ALOFT SEEMS TO SUPPORT THE MORE SUPPRESSED SCENARIO. NEXT BUNDLE OF SHRTWV ENERGY SHOULD REACH WRN NOAM AROUND SAT-SUN... SUPPORTING A PLAINS/MS VLY SYSTEM BY DAY 6 MON. OPERATIONAL GFS/ECMWF/CMC RUNS AGREE THAT THIS SYSTEM SHOULD BE BETTER DEVELOPED THAN LATEST GEFS MEANS BY DAY 7 TUE. HOWEVER WITH COMPLEX FLOW ALONG THE US-CANADIAN BORDER DETERMINING EXACTLY HOW STRONGLY THE SFC LOW WRAPS UP... AND SUCH DETAILS USUALLY NOT EASILY RESOLVED 6-7 DAYS OUT IN TIME... PREFER THE 00Z ECMWF MEAN AS THE BEST WAY TO DEPICT A DEVELOPED SYSTEM WEAKER THAN OPERATIONAL ECMWF/CMC RUNS AND A LITTLE SLOWER THAN GFS RUNS. FARTHER UPSTREAM EXPECT YET ANOTHER FRONTAL SYSTEM OR TWO TO APPROACH THE WEST COAST EARLY NEXT WEEK BUT WITH TYPICALLY LOW CONFIDENCE FOR EXACT TIMING. ...SENSIBLE WEATHER HIGHLIGHTS... OVER THE WEST... RAPID PROGRESSION OF FRONTAL SYSTEMS AROUND THE SERN SIDE OF THE NERN PAC MEAN TROUGH WILL BRING MULTIPLE PERIODS OF ENHANCED RNFL AND HIGHER ELEV SNOW TO AREAS FROM THE NRN-CNTRL WEST COAST AND TO A SOMEWHAT LESSER EXTENT NRN HALF OF THE ROCKIES. TO THE S/SE OF THE MAIN PCPN SHIELD EXPECT WARM TEMPS OVER THE SRN HALF TO 2/3 OF THE INTERIOR WEST/ROCKIES WITH SOME LOCATIONS SEEING ONE OR MORE DAYS WITH HIGHS 15-20F ABOVE NORMAL. SOME OF THIS WARMTH SHOULD EXTEND INTO THE PLAINS BY THE WEEKEND. FARTHER EWD POTENTIAL EXISTS FOR THE SHORT RANGE EAST COAST STORM TO GENERATE LINGERING SNOW OVER NRN NEW ENGLAND INTO FRI. THEN A GRTLKS SYSTEM TRACKING OFFSHORE BY SAT MAY BE ACCOMPANIED BY AN AREA OF LGT SNOW WITH RNFL OR A MIX IN WARMER AIR TO THE S ALONG THE TRAILING COLD FRONT. GREATER UNCERTAINTY EXISTS WITH THE EVOLUTION OF A CNTRL-ERN WAVE DURING THE WEEKEND... WITH A BAND OF SNOW LIKELY TO OCCUR TO THE N OF THE SFC LOW TRACK. ANOTHER DEVELOPING PLAINS/ERN US SYSTEM MAY BRING A MORE ORGANIZED PCPN SHIELD ACROSS THE ERN HALF OF THE CONUS BY NEXT MON-TUE. ERN AREAS SHOULD BE ON THE CHILLY SIDE LATE THIS WEEK INTO THE WEEKEND WITH TEMPS MODERATING BY EARLY NEXT WEEK. RAUSCH