MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1203 AM EST SUN FEB 02 2014 VALID FEB 02/0000 UTC THRU FEB 05/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... ============================================== 00Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES ============================================== NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT. ============================================== ...SOUTHERN STREAM WAVE TRACKING FROM SOUTHWEST TO THE MID ATLANTIC SUN-MON... PREFERENCE: GFS/UKMET/12Z ECMWF MODEL SPREAD REMAINS SLIGHT BUT ENOUGH TO CREATE SIGNIFICANT DIFFERENCES IN THE MODEL QPFS FROM THE SOUTHERN PLAINS TO THE MID ATLANTIC REGION. SO FAR THE 00Z RUNS HAVE DIVERGED LITTLE FROM THEIR 12Z RUNS. THE NAM REMAINS SLIGHTLY MORE AMPLIFIED...ESPECIALLY AT 700MB AS THE WAVE MOVES OUT INTO THE SOUTHERN PLAINS LATER TODAY. THEN AS THIS SYSTEM MOVES FROM THE TN VALLEY INTO THE MID ATL REGION ON MON THE SPREAD ALOFT REMAIN SLIGHT...HOWEVER DIFFERENCES AT THE SURFACE BECOME A LITTLE MORE PRONOUNCED...WITH THE UKMET/12Z ECMWF AND CMC GLOBAL SLOWER AND MORE AMPLIFIED THAN THE NCEP MODELS. WPC WILL CONTINUE TO PREFER A BLEND OF THE GFS/00Z ECMWF ALONG WITH THE UKMET WITH THIS SYSTEM. FOR MORE ON THE QPF AND WINTER WEATHER ASSOCIATED WITH THIS SYSTEM... PLEASE REFER TO THE LATEST QPFPFD AND QPFHSD RESPECTIVELY. ...SHORTWAVE DIGGING THROUGH CALIFORNIA AND EJECTING TO THE MIDWEST SUN-TUES... PREFERENCE: GFS/UKMET/12Z ECMWF SIGNIFICANT MODEL DIFFERENCES DO NOT EMERGE UNTIL MON NIGHT-TUE MORNING WHEN THE NAM MOVES TO THE DEEP PROGRESSIVE SIDE OF THE GUIDANCE WITH THE UPPER TROUGH AS IT MOVES ACROSS THE SOUTHWEST-SOUTHERN ROCKIES. THE NAM REMAINS A PROGRESSIVE OUTLIER ALOFT LIFTING THE TROUGH FROM THE SOUTHERN HIGH PLAINS TO THE MID MS VALLEY ON TUE. AT THE SURFACE...IT DEVELOPS AND TRACKS THE THE ASSOCIATED LOW WELL TO THE NORTH OF THE MODEL CONSENSUS THROUGH THE OH VALLEY INTO THE LOWER GREAT LAKES REGION. ...NORTHERN STREAM UPPER TROUGH SETTLING INTO NW/NRN ROCKIES/PLAINS MON-TUES... PREFERENCE: BLEND OF THE OPERATIONAL MODELS OVERALL THERE IS A GENERAL MODEL CONSENSUS THAT A NUMBER OF SHORTWAVES EMBEDDED WITHIN BROAD NORTHERLY FLOW REGIME WILL HELP ESTABLISH AN ANOMALOUS NORTHERN STREAM UPPER TROUGH ACROSS THE NORTHWEST TO THE NORTHERN PLAINS/UPPER MIDWEST. THIS SHOULD DRIVE A STABLE ARCTIC AIR MASS INTO THE REGION...POTENTIALLY INTERACTING WITH THE SOUTHERN STREAM SHORTWAVE ARRIVING INTO THE MIDWEST. www.wpc.ncep.noaa.gov/html/model2.shtml... PEREIRA