MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1211 AM EST SUN JAN 26 2014 VALID JAN 26/0000 UTC THRU JAN 29/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS NO SIGNIFICANT INITIALIZATION ERRORS WERE SEEN IMPACTING THE SHORT RANGE FORECAST. ...NEXT ARCTIC OUTBREAK LED BY LOW PRESSURE CROSSING OVER THE GREAT LAKES... PREFERENCE: GENERAL MODEL COMPROMISE...WITH THE SURFACE LOW 00Z GFS...WITH THE FRONTAL TIMING CONFIDENCE: ABOVE AVERAGE LOW PRESSURE ALREADY SITUATED OVER THE NRN PLAINS ATTM WILL ADVANCE PROGRESSIVELY ESEWD ACROSS THE UPR MIDWEST EARLY SUN AND THEN CROSS THE GREAT LAKES BY SUN NIGHT. THEREAFTER...THE SFC LOW ALONG WITH A RATHER ROBUST SHORTWAVE TROUGH CROSSING THE GREAT LAKES REGION WILL LIFT NEWD UP INTO THE ST LAWRENCE RIVER VLY AND ADJACENT AREAS OF NRN NEW ENGLAND. AN ARCTIC COLD FRONT ASSOCD WITH THE ADVANCING SFC LOW AND ENERGY ALOFT WILL CROSS THE CNTRL AND ERN U.S. THROUGH THE PERIOD...ALLOWING FOR ANOTHER SURGE OF ANOMALOUSLY COLD TEMPERATURES TO AGAIN SURGE SOUTH AND EAST IN ITS WAKE AS A ARCTIC HIGH PRESSURE SETTLES SOUTH OUT OF CANADA. THE LATEST GLOBAL MODELS ARE REASONABLY WELL CLUSTERED WITH THE DETAILS OF THE SFC LOW EVOLUTION. REGARDING THE ARCTIC COLD FRONT...THE 00Z NAM AND 12Z UKMET ARE A TAD SLOWER THAN THE GLOBAL MODEL CONSENSUS. THE 00Z GFS IS THE FASTEST...FOLLOWED BY THE 12Z GEM GLOBAL AND 12Z ECMWF. THE 18Z GEFS MEAN AND 12Z ECENS MEAN SUPPORT THEIR RESPECTIVE DETERMINISTIC MODELS. WOULD PREFER TO HEDGE A LITTLE MORE PROGRESSIVE LIKE THE 00Z GFS WITH THE FRONT GIVEN THE DEGREE OF ARCTIC AIR/HIGH PRESSURE NOSING IN BEHIND THE EXITING SFC LOW. OTHERWISE...A GENERAL MODEL COMPROMISE WILL BE PREFERRED WITH THE SFC LOW. ...SOUTHERN STREAM TROUGH/CLOSED LOW IMPACTING THE SOUTHWEST/BAJA CALIFORNIA... PREFERENCE: 12Z ECMWF/12Z UKMET/12Z GEM GLOBAL BLEND CONFIDENCE: AVERAGE THE MODELS SHOW SOME SRN STREAM SHORTWAVE ENERGY BREAKING AWAY FROM THE DEEP TROUGH SOUTH OF THE ALEUTIANS AND ADVANCING NEAR SRN CA AND ADJACENT AREAS OF THE BAJA PENINSULA AS A CLOSED MID LVL LOW CENTER SUN NIGHT AND MON. THE 12Z ECMWF/12Z UKMET AND 12Z GEM GLOBAL ALL SUGGEST THE CLOSED LOW SLOWING DOWN AND SETTLING FARTHER SOUTH DOWN THE BAJA PENINSULA THROUGH TUES. THE 00Z GFS AND 00Z NAM THOUGH ARE MORE PROGRESSIVE AND ACTUALLY TREND WEAKER WITH THE ENERGY AS IT CROSSES INTO NWRN MEXICO. THE NAM AND GFS THEN SHEAR THIS ENERGY OUT ACROSS THE RIO GRANDE VLY ALONG WITH THEIR ATTENDANT SUBTROPICAL MOISTURE FEEDS BY TUES NIGHT/WED...HELPING TO ALSO IGNITE A WETTER SOLN FOR THE GULF COAST STATES. THE 18Z GEFS MEAN AND 12Z ECENS MEAN SUPPORT THE SLOWER/CLOSED LOW SCENARIO OF THE NON-NCEP SOLNS. THE NAM AND GFS HAVE LITTLE SUPPORT FOR THEIR PROGRESSIVE/SHEARED SOLNS...AND BASED ON MODEL TRENDS AND ENSEMBLE SUPPORT...WILL FAVOR A NON-NCEP CONSENSUS. ...SHORTWAVE ENERGY DIGGING TOWARD THE SOUTHERN PLAINS/LOWER MS VALLEY/GULF COAST... PREFERENCE: 12Z ECMWF CONFIDENCE: AVERAGE THE MODELS IN GENERAL AGREE THERE WILL SOME AMPLIFICATION OF SHORTWAVE ENERGY THAT DIGS SEWD ACROSS THE CNTRL/SRN PLAINS AND EASTWARD ACROSS THE LWR MS VLY/TN VLY AND GULF COAST STATES TUES AND WED. THE 00Z NAM IS BY FAR...AS IT HAS BEEN WITH ITS LAST COUPLE OF MODEL CYCLES...TOO AGGRESSIVE WITH THE AMPLIFICATION OF THIS ENERGY. ADDITIONALLY...THE NAM APPEARS TO BE GETTING SOME SUPPORT FROM THE SRN STREAM ENERGY THAT EJECTS ACROSS THE SOUTHWEST/BAJA PENINSULA AND ITS ASSOCD SUBTROPICAL MOISTURE FETCH. THE NAM IS AN OUTLIER SOLN WITH THAT ENERGY OVER THE SOUTHWEST AS IT IS TOO FAST/WEAK WITH THE SYS. THEREFORE BY TUES AND WED...THE REMNANTS OF THAT ENERGY IS GETTING PICKED UP BY THE STRONGER AND MORE AMPLIFIED NRN STREAM ENERGY DIGGING DOWN THROUGH THE PLAINS/LWR MS VLY. THIS HAS BEEN DRIVING THE WETTER NAM SOLN ALONG THE GULF COAST ALONG WITH AN IMPLIED SIGNIFICANT WINTER WX THREAT GIVEN THE DEGREE OF MODIFIED ARCTIC AIR POURING SOUTH ACROSS THE CNTRL/ERN U.S. THROUGH THE PERIOD. THE 00Z GFS WHILE IT IS NO WHERE NEAR AS AMPLIFIED AS THE 00Z NAM...STILL HAS A PROBLEM FOR THE GULF COAST STATES. AS MENTIONED BEFORE...THE 00Z GFS IS PROGRESSIVE/SHEARED WITH THE ENERGY IN THE SOUTHWEST LIKE THE NAM. IT HAS A SUFFICIENT INTRUSION OF SRN STREAM ENERGY AND MOISTURE FOR A WETTER SOLN ALONG THE GULF COAST ALTHOUGH NOT AS WET AS THE NAM. THE NON-NCEP SOLNS BY IN LARGE...ESP LED BY THE 12Z ECMWF AND 12Z UKMET...DO NOT FAVOR SUCH AN INTERACTION BETWEEN NRN AND SRN STREAMS. THE 12Z UKMET IS THE MOST PROGRESSIVE/WEAKEST WITH THE NRN STREAM ENERGY...FOLLOWED BY THE 12Z GEM GLOBAL AND 12Z ECMWF. THE 12Z ECMWF DOES INDICATE SOME HINTS AT A SOMEWHAT MORE AMPLIFIED SHORTWAVE ALBEIT IT PROGRESSIVE OVER THE TN VLY BY EARLY WED...BUT THERE IS LITTLE TO NO INTERACTION WITH THE SRN STREAM FEED AND IS THEREFORE CONSIDERABLY DRIER AT LEAST THROUGH EARLY WED. THE 18Z GEFS MEAN AND 12Z ECENS MEAN SUPPORT THE FLATTER/WEAKER CONSENSUS WITH THE NRN STREAM ENERGY. BASED ON SIGNIFICANT CONCERNS OF THE MASS FIELDS OF THE NAM AND GFS AND THEIR STREAM INTERACTIONS...WILL FAVOR A NON-NCEP CONSENSUS LED HEAVILY BY THE 12Z ECMWF. ...PACIFIC NORTHWEST... PREFERENCE: 12Z ECMWF/12Z UKMET BLEND CONFIDENCE: AVERAGE THE MODELS REMAIN IN GENERAL AGREEMENT THAT A SHORTWAVE TROUGH SHOULD SURVIVE ITS VOYAGE INTO THE MEAN RIDGE POSITION TUES AND WED OVER THE PAC NORTHWEST. THE 00Z NAM AND ESP THE 00Z GFS SUGGEST MORE SUBSTANTIAL ENERGY TOPPING THE RIDGE AXIS. THE 12Z GEM GLOBAL SUPPORTS THIS TOO. THE 12Z UKMET AND 12Z ECMWF ALONG WITH THE 12Z ECENS MEAN SUGGEST THE MEAN RIDGE HANGING TOUGH AND NOT WEAKENING AS MUCH. THE 18Z GEFS MEAN TENDS TO FAVOR THE 00Z GFS SOLN. BASED ON THE PERSISTENCE OF THE STRONGER MEAN LAYER RIDGE OF LATE...WILL PREFER A SOLN TWD A MORE MODEST BREAKING DOWN OF THE RIDGE AXIS. WILL PREFER A BLEND OF THE 12Z UKMET AND 12Z ECMWF ATTM AS A RESULT. www.wpc.ncep.noaa.gov/html/model2.shtml... ORRISON