MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1158 AM EST MON FEB 23 2015 VALID FEB 23/1200 UTC THRU FEB 27/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SHORTWAVE TROUGH CROSSING THE GREAT LAKES/NORTHEAST... ...SURFACE LOW IMPACTING EASTERN NEW ENGLAND BY EARLY WED... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW A NORTHERN STREAM TROUGH CROSSING THE GREAT LAKES AND NORTHEAST TUES AND WED WHICH WILL DRIVE A REINFORCING ARCTIC COLD FRONT ACROSS THE REGION. THIS ENERGY COUPLED WITH A LEAD SHORTWAVE IMPULSE WILL DEVELOP AN AREA OF LOW PRESSURE JUST OFF EASTERN NEW ENGLAND BY EARLY WED. THE 00Z UKMET IS A TAD LEFT OF THE MULTI-MODEL CONSENSUS. GIVEN THE STRONG CLUSTERING OF THE REMAINING MODELS...A NON-UKMET CONSENSUS WILL BE PREFERRED. ...SHORTWAVE CROSSING THE GULF COAST STATES THROUGH TUES... ...LOW PRESSURE DEVELOPMENT OFF THE SOUTHEAST COAST... PREFERENCE: 00Z ECMWF CONFIDENCE: ABOVE AVERAGE A SHORTWAVE WILL BE SHEARING OUT ACROSS THE GULF COAST STATES THROUGH TUES...AND THIS ENERGY WILL BE FOCUSING A WAVE OF LOW PRESSURE OFF THE SOUTHEAST COAST BY LATE TUES. THE 12Z GFS OVERALL APPEARS TO BE THE WEAKEST SOLUTION...WITH THE 12Z NAM THE STRONGEST. THE STRONGER MODEL SUPPORT CENTERS ON A SOLUTION IN THE MIDDLE AS SUGGESTED BY A CONSENSUS OF THE 00Z ECMWF/00Z UKMET AND 00Z GEM. WILL PREFER A NON-NCEP CONSENSUS LED BY THE 00Z ECMWF. ...UPPER LOW EJECTING OUT OF THE SOUTHWEST... ...SURFACE LOW DEVELOPING OVER THE GULF OF MEXICO... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z UKMET CONFIDENCE: AVERAGE A CLOSED LOW IN THE SOUTHWEST U.S. WILL BECOME AN OPEN BUT SHARP TROUGH AS IT APPROACHES TEXAS BY WEDNESDAY. THIS WILL INDUCE A WAVE ALONG A FRONT IN THE NORTHERN GULF OF MEXICO AND CROSSING NORTHERN FLORIDA INTO THE ATLANTIC. THE 12Z NAM TRENDED MORE AMPLIFIED WITH THIS SYSTEM AS IT EJECTS EAST ACROSS THE GULF COAST STATES...BUT IT IS THE MOST AMPLIFIED SOLUTION OF ALL THE MODELS. THE 12Z GFS FOR ITS PART IS THE FLATTEST/WEAKEST SOLUTION. THE 00Z UKMET/00Z GEM AND 00Z ECMWF SPLIT THE DIFFERENCE...BUT THE GEM APPEARS TO BE TOO SUPPRESSED WITH ITS WAVE TRACK. THE STRONGER MODEL CLUSTERING FAVORS A BLEND OF THE ECMWF AND UKMET AND SO THIS WILL BE THE PREFERENCE. ...STRENGTHENING TROUGHING OVER THE NORTHERN U.S. BY THURS... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS FEATURE SIMILAR HANDLING OF ANOTHER IS A SERIES OF DEEP NORTHERN STREAM TROUGHS TO CROSS THE NORTHERN TIER OF THE COUNTRY. THIS NEXT TROUGH WILL CROSS THE UPPER MIDWEST AND GREAT LAKES REGION WED AND THURS AND WILL LEAD THE WAVE FOR ANOTHER ARCTIC SURFACE HIGH TO NOSE SOUTH THROUGH THE PLAINS. THERE IS SUFFICIENT AGREEMENT AMONG THE MODELS FOR A GENERAL MODEL COMPROMISE TO BE USED HERE. ...WESTERN U.S. IN THE WAKE OF THE INITIAL SOUTHWEST STORM... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z ECENS MEAN CONFIDENCE: BELOW AVERAGE AS A CLOSED LOW EXITS THE SOUTHWEST U.S...HEIGHTS GENERALLY RISE ALONG THE WEST COAST AND INTERMOUNTAIN REGION...BUT WITH SOME BUCKLING OF THE NORTHWESTERLY FLOW AS PACIFIC SHORTWAVES DIVE FROM THE NORTHWEST U.S. TOWARD THE SOUTHERN ROCKIES. THE MODELS ARE NOT HANDLING THESE LOW AMPLITUDE WAVES VERY CONSISTENTLY FROM RUN TO RUN. THERE IS A FAIR DEGREE OF SPREAD WED AND THURS WITH THE DETAILS OF HOW THE ENERGY DIGS THROUGH THE INTERMOUNTAIN REGION. THE 12Z GFS TENDS TO BE A MORE AMPLIFIED WITH THESE WAVES VERSUS THE MULTI-MODEL CONSENSUS. THE 00Z GEM AND THE 12Z NAM BECOME THE FLATTEST...AND IN THE CASE OF THE NAM THIS IS MAINLY A RESULT OF IT PLACING MUCH MORE ENERGY UPSTREAM NEAR BRITISH COLUMBIA. THE 00Z ECMWF OFFERS A NICE COMPROMISE FOR THE TIME BEING GIVEN ITS REASONABLE SOLUTION IN BETWEEN THE GFS AND NAM CAMPS. THE ECMWF ALSO HAS SOLID SUPPORT FROM THE 00Z ECENS MEAN...HOWEVER CONFIDENCE IS LIMITED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON