MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 157 PM EST FRI MAR 10 2017 VALID MAR 10/1200 UTC THRU MAR 14/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...AMPLIFYING SHORTWAVE CROSSING SOUTHERN NEW ENGLAND... ...INTENSE LOW CENTER DEEPENING OFFSHORE NEW ENGLAND... ...DEEP UPPER LOW/TROUGH DROPPING ACROSS SOUTHEAST CANADA... PREFERENCE: NON-UKMET CONSENSUS CONFIDENCE: ABOVE AVERAGE WATER VAPOR IMAGERY AND MID-LEVEL HEIGHT FIELDS SHOW BROAD CYCLONIC FLOW ACROSS MUCH OF EASTERN NORTH AMERICA WITH AN EMBEDDED SHORTWAVE SEEN AMPLIFYING ACROSS THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND. THIS SYSTEM WILL CONTINUE TO DEEPEN TONIGHT AND WILL ALLOW SURFACE LOW PRESSURE EXITING AWAY FROM NEW ENGLAND TO RAPIDLY INTENSIFY TOWARD THE CANADIAN MARITIMES OF SOUTHEAST CANADA TONIGHT AND SAT. IN THE WAKE OF THIS SYSTEM...A BROADER AND DEEPER UPPER LOW WILL DROP ACROSS SOUTHEAST CANADA AND MAINTAIN A TROUGH DOWN ACROSS THE NORTHEAST THROUGH SAT. THE 12Z UKMET BECOMES A BIT DEEPER AND SLOWER THAN THE MODEL CONSENSUS AS THE LOW CENTER PULLS AWAY FROM THE EAST COAST. GIVEN GOOD MODEL AGREEMENT SEEN OTHERWISE...A NON-UKMET CONSENSUS WILL BE PREFERRED. ...SLOW-MOVING MYRIAD OF MESOSCALE VORTICES TRACKING FROM MX TOWARD/ALONG THE GULF COAST... ...POTENTIAL SURFACE LOW IN THE GULF OF MX/SOUTHEASTERN U.S... PREFERENCE: BLEND OF THE 12Z GFS/12Z ECMWF AND 00Z ECENS MEAN CONFIDENCE: BELOW AVERAGE A RATHER EXPANSIVE AREA OF UNSETTLED WEATHER ACROSS CENTRAL/EASTERN MX WILL GRADUALLY SHIFT ITS FOCUS TOWARD THE NORTH AND EAST OVER THE NEXT COUPLE OF DAYS. CURRENT SATELLITE IMAGERY SHOWS AN ELONGATED AREA OF MID LEVEL TROUGHING ACROSS CENTRAL AND NORTHEAST MX...WITH EMBEDDED SMALLER SCALE VORTS. OVER THE NEXT TWO DAYS...A PORTION OF THIS ENERGY WILL EJECT EAST ACROSS THE GULF COAST IN CONJUNCTION WITH A LOW-AMPLITUDE NORTHERN STREAM SHORTWAVE DROPPING EAST-SOUTHEAST OUT OF THE ROCKIES. THIS WILL ALLOW FOR THE POTENTIAL FOR SURFACE LOW PRESSURE TO DEVELOP OVER THE NORTHERN GULF OF MEXICO BY SUN BEFORE THEN CONSOLIDATING OFF THE SOUTHEAST COAST ON MON. THE 12Z ECMWF IS OVERALL THE STRONGEST SOLUTION WITH THE GULF OF MEXICO WAVE DEVELOPMENT...OWING TO A BIT STRONGER SOUTHERN STREAM ENERGY. THE 12Z UKMET AND 12Z CMC HAVE TRENDED A BIT WEAKER AND ARE REASONABLY CLOSE TO THE 12Z NAM AND 12Z GFS WITH THE SOUTHERN STREAM SYSTEM. THE 12Z NAM IS TENDING THE BE THE STRONGEST WITH THE NORTHERN STREAM ENERGY WITH THE REMAINING GUIDANCE A BIT FLATTER. ENSEMBLE SUPPORT FOR A WAVE IN THE NORTHERN GULF OF MEXICO IS LARGELY SUPPORTED BY THE EURO SUITE WITH A NUMBER OF MEMBERS STILL ADVERTISING A LOW CENTER. THE GFS AND CMC-BASED ENSEMBLE SUITES SHOW MUCH FEWER MEMBERS SUPPORTING THIS. CONFIDENCE IS BELOW AVERAGE...BUT THE BEST COURSE OF ACTION IS TO COMPROMISE BETWEEN WEAKER AND STRONGER CAMPS...AND ESPECIALLY WITH THE CONSISTENCY SEEN WITH THE ECMWF CAMP. WILL MAINTAIN A GFS/ECMWF AND ECENS MEAN BLEND AT THIS TIME. ...SHORTWAVE CROSSING THE NORTHWEST SAT NIGHT... ...AMPLIFYING TOWARD THE MID MS/LOWER OH/TN VALLEYS ON MON... PREFERENCE: BLEND OF THE 12Z GFS/12Z UKMET AND 12Z ECMWF CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE ONE IMPORTANT PLAYER TO THE EVOLUTION OF LOW PRESSURE OFF THE SOUTHEAST COAST ON MON WILL BE THE ARRIVAL OF AN UPSTREAM SHORTWAVE THAT WILL CROSS THE NORTHWEST U.S. LATE SAT THROUGH EARLY SUN...AND THEN DIG RATHER VIGOROUSLY SOUTHEAST TOWARD THE MID MS/LOWER OH AND TN VALLEYS THROUGH MON. THE SYSTEM AS IT ARRIVES ACROSS THE PACIFIC NORTHWEST WILL BECOME A BIT ELONGATED AND ESPECIALLY AT THE SURFACE...WITH LOW PRESSURE AND A FRONT CROSSING WESTERN WA AND SOUTHERN BRITISH COLUMBIA WHILE ELONGATING BACK OFFSHORE. THERE TENDS TO BE A BIT BETTER MODEL CLUSTERING BETWEEN THE 12Z GFS/12Z ECMWF AND 12Z UKMET. THE 12Z NAM APPEARS TOO WEAK WITH THE SYSTEM...AND THE 12Z CMC FOCUSES TOO MUCH LOW PRESSURE FARTHER OFFSHORE AS THE MAIN SHORTWAVE ARRIVES. A PORTION OF THIS SYSTEM WILL LIFT NORTH THROUGH BRITISH COLUMBIA...WHILE THE REMAINDER OF IT DROPS SOUTHEAST OVER THE MEAN RIDGE AXIS OVER THE WESTERN U.S. THE 12Z GFS AMPLIFIES THIS ENERGY MORE SO THAN ANY OTHER MODEL AS IT APPROACHES THE MID MS/LOWER OH AND TN VALLEYS SUN THROUGH MON. HOWEVER...THE 12Z UKMET ALSO TENDS TO SUPPORT THE STRONGER GFS OVER THIS REGION WITH TIME AND ESPECIALLY AS THE ENERGY MOVES INTO THE OH/TN VALLEYS. BY MON...THE 12Z GFS HAS THE STRONGEST LOW CENTER OVER THE OH VALLEY...WITH THE 12Z CMC THE WEAKEST. MEANWHILE...THE STRENGTH OF THIS TROUGH WILL BEGIN TO HAVE AN IMPACT ON THE LOW PRESSURE CENTER OFF THE SOUTHEAST COAST. THE 12Z ECMWF IS TUCKING A STRONGER LOW CENTER IN A LITTLE CLOSER IN TOWARD THE SC COAST BY LATE MON AS IT HAS A BIT STRONGER INTERACTION GOING ON BETWEEN THE DIGGING NORTHERN STREAM TROUGH AND THE SOUTHERN STREAM ENERGY CROSSING THE GULF COAST. THE REMAINING MODELS AT LEAST THROUGH LATE MON HAVE A BIT MORE STREAM SEPARATION AND ARE A BIT WEAKER...ALTHOUGH THE 12Z NAM IS AN OUTRIGHT WEAK OUTLIER. AT THIS POINT...THE GFS ENSEMBLES AND EURO ENSEMBLES GENERALLY REMAIN IN SUPPORT OF THEIR RESPECTIVE DETERMINISTIC GFS/ECMWF OUTPUT. CONFIDENCE BECOMES LIMITED BY LATE IN THE PERIOD...BUT ACCOUNTING FOR ENSEMBLE SUPPORT AND TRENDS...A COMPROMISE BETWEEN THE GFS/UKMET AND ECMWF WILL BE PREFERRED. ...STRONG NORTHERN STREAM TROUGH DIGGING ACROSS THE UPPER MIDWEST ON MON... PREFERENCE: NON-CMC CONSENSUS CONFIDENCE: AVERAGE THE MODELS SHOW A STRONG NORTHERN STREAM TROUGH DIGGING INTO THE UPPER MIDWEST ON MON. THE 12Z UKMET/12Z CMC AND 12Z ECMWF HAVE ALL GENERALLY TRENDED STRONGER AND CLOSER TO THE ALREADY STRONGER 12Z GFS AND 12Z NAM SOLUTIONS. THE CMC THOUGH APPEARS TO BE TOO PROGRESSIVE. WILL PREFER A NON-CMC CONSENSUS AT THIS POINT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON