MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1217 AM EDT FRI MAY 09 2014 VALID MAY 09/0000 UTC THRU MAY 12/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE TROUGH LIFTING THROUGH THE UPPER MIDWEST/GREAT LAKES... ...SURFACE LOW ADVANCING NORTHEAST INTO ONTARIO... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE ALL OF THE MODELS CONTINUE TO ADVERTISE THE NEWD EJECTION OF THE SHORTWAVE TROUGH CURRENTLY OVER THE PLAINS UP THROUGH THE UPPER MIDWEST AND CROSSING THE UPPER GREAT LAKES REGION THROUGH FRI. THIS WILL INCLUDE THE ASSOCD SFC LOW WHICH IS EXPECTED TO LIFT NEWD INTO ONTARIO BY LATE FRI. A TRAILING COLD FRONT WILL ADVANCE EASTWARD AND MOVE THROUGH THE MID MS VLY THROUGH FRI AND THEN INTO THE OH VLY ON SAT WHILE ALSO SLOWING DOWN AND WEAKENING. THERE IS RELATIVELY MINOR SPREAD SFC AND ALOFT WITH THE ENERGY LIFTING OUT INTO SERN CANADA OVER THE NEXT COUPLE OF DAYS...SO WILL PREFER A GENERAL MODEL COMPROMISE ATTM TO RESOLVE ANY SMALLER SCALE DIFFS THAT REMAIN. ...UPPER TROUGH MOVING THROUGH THE NORTHWEST/GREAT BASIN... ...CLOSED LOW DEVELOPMENT NEAR THE FOUR CORNERS REGION BY SUN... ...LEE-SIDE CYCLOGENESIS OVER THE CENTRAL HIGH PLAINS BY SUN... PREFERENCE: 12Z ECMWF/12Z ECENS MEAN CONFIDENCE: BELOW AVERAGE THE MODELS INDICATE THAT THE CLOSED UPR LOW CURRENTLY ADVANCING SEWD FROM THE GULF OF AK WILL ADVANCE PROGRESSIVELY INTO THE PAC NORTHWEST BY FRI NIGHT. THE MODELS SHOW THIS ENERGY THEN DIGGING ACROSS THE GREAT BASIN AND THE FOUR CORNERS REGION SAT AND SUN AND SUPPORT THE IDEA OF A CLOSED LOW CROSSING THE INTERIOR BEFORE THEN OPENING BACK UP INTO A N/S TROUGH AXIS BY MON WHILE ATTEMPTING TO EJECT OUT INTO THE PLAINS. THE HEIGHT FALLS WILL FOSTER LEE-SIDE CYCLOGENESIS OVER THE CNTRL HIGH PLAINS BY SAT WITH LOW PRESSURE THEN EXPECTED TO LIFT NEWD INTO THE MIDWEST BY LATE SUN AND MON. THE 00Z GFS BEGINNING LATE SAT AND ESP SUN AND MON BECOMES A FASTER AND RELATIVELY WEAK OUTLIER WITH THE EVOLUTION OF THE HEIGHT FALLS ACROSS THE GREAT BASIN AND THROUGH THE FOUR CORNERS REGION. ON MON...IT HAS AN OPEN TROUGH AXIS WELL OUT INTO THE PLAINS WHICH DRIVES SFC LOW PRESSURE AND ESP ITS SFC FRONT FASTER OFF TO THE EAST AND NORTHEAST. THE 00Z NAM AND 12Z UKMET APPEAR REASONABLY CLOSE TO THE GLOBAL MODEL CONSENSUS UNTIL SUN NIGHT AND MON WHEN THEY SUGGEST ALSO A SOMEWHAT MORE PROGRESSIVE SOLN. THE 12Z ECMWF AND 12Z GEM ARE SLOWER AND THESE MODELS ARE BETTER SUPPORTED BY THE 12Z ECENS MEAN. THE 12Z GEM OVERALL IS THE STRONGEST SOLN ALOFT...AND MAY BE A TAD TOO STRONG. BASED ON RELATIVELY BETTER RUN TO RUN MODEL CONTINUITY...WILL PREFER A BLEND OF THE ECMWF AND ECENS MEAN...HOWEVER CONFIDENCE IS LIMITED GIVEN THE OVERALL MODEL SPREAD IN THE PLAINS BY MON. ...CLOSED LOW PERSISTING OVER NORTHERN SASKATCHEWAN... ...UPPER TROUGH EXTENDING SOUTH INTO THE NORTHERN PLAINS... ...SURFACE LOW DEVELOPMENT OVER THE FAR NORTHERN PLAINS... PREFERENCE: 12Z GEM/12Z ECMWF COMPROMISE CONFIDENCE: AVERAGE THE MODELS INDICATE A CLOSED LOW THAT IS OVER NRN SASKATCHEWAN SHOULD PERSIST UNTIL LATE SAT WHEN IT IS EXPECTED TO WEAKEN AND POTENTIALLY REDEVELOP FARTHER SOUTH OVER SRN SASKATCHEWAN OR POTENTIALLY THE FAR NRN PLAINS SUN AND MON. THE SWD EXTENSION OF THE HEIGHT FALLS INTO THE NRN PLAINS IS AGAIN EXPECTED TO INVIGORATE AN AREA OF LOW PRESSURE OVER THE FAR NRN PLAINS NEAR THE CANADIAN BORDER. THE 00Z GFS KEEPS MUCH MORE OF THE ORIGINAL CLOSED LOW OVER CNTRL CANADA INTACT AND DOES NOT DROP NEARLY AS MUCH ENERGY FARTHER SOUTH TWD THE U.S./CANADIAN BORDER AS DOES THE 12Z UKMET/12Z GEM AND 12Z ECMWF. THE 00Z NAM DOES ALLOW FOR MORE SWD EXTENSION OF HEIGHT FALLS THROUGH THE PERIOD...BUT APPEARS A BIT TOO DEEP ALOFT OVER THE NRN PLAINS OVERALL SUN AND MON. THE 12Z GEM AND 12Z ECMWF CLUSTER THE BEST OVERALL AND ARE REASONABLY WELL SUPPORTED BY THE 12Z ECENS MEAN. ...SHORTWAVE IMPULSE TRAVERSING THE NORTHERN GULF OF MEXICO PREFERENCE: NON-ECMWF CONSENSUS CONFIDENCE: AVERAGE ALL OF THE MODELS SHOW A WEAK SRN STREAM SHORTWAVE IMPULSE TRAVERSING THE NRN GULF OF MEXICO AND POTENTIALLY IMPACTING THE IMMEDIATE GULF COAST STATES. THE 12Z ECMWF WAS A RELATIVELY STRONG OUTLIER WITH THE VORT ENERGY ASSOCD WITH THIS SYS. WILL PREFER A NON-ECMWF CONSENSUS ATTM. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON