Prognostic Meteorological Discussion
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000 FXUS10 KWNH 240658 PMDHMD MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 257 AM EDT FRI MAR 24 2017 VALID MAR 24/0000 UTC THRU MAR 27/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF ...CLOSED LOW DIVING THROUGH EASTERN CANADA BY SAT MORNING... ...COLD FRONT ADVANCING DOWN ACROSS THE GREAT LAKES/NORTHEAST... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE DIFFERENCES AT THIS POINT ARE RATHER MODEST WITH THE EVOLUTION OF THE STRONG UPPER LOW MOVING INTO EASTERN CANADA AND THE COLD FRONT SWEEPING SOUTHEAST ACROSS THE GREAT LAKES AND NORTHEAST. A GENERAL MODEL COMPROMISE WILL BE PREFERRED AT THIS TIME. ...CLOSED LOW EVOLUTION OVER THE CENTRAL PLAINS FRI... ...ENERGY CROSSING THE MID MS/OH VALLEYS THROUGH SAT... ...SYSTEM WEAKENING INTO THE GREAT LAKES BY SUN/MON... PREFERENCE: NON-NAM CONSENSUS CONFIDENCE: AVERAGE THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE 00Z CYCLE...WITH THE ECMWF HAVING TRENDED A LITTLE MORE PROGRESSIVE AND RATHER CLOSE TO THE MODEL CONSENSUS. THE CMC WHICH HAD BEEN MORE PROGRESSIVE AND FARTHER NORTH WITH ENERGY REACHING THE GREAT LAKES REGION IS NOW A BIT SLOWER. HOWEVER...THE NAM AT THIS POINT DOES APPEAR TO BE TOO FAST IN LIFTING ITS SURFACE WAVE NORTHEAST OUT OF THE MID MS VALLEY AND ACROSS THE GREAT LAKES REGION. THE GLOBAL MODELS ARE WELL CLUSTERED IN BEING A LITTLE SLOWER AND SOUTHWEST OF THE NAM SOLUTION. WILL PREFER A NON-NAM CONSENSUS AS A RESULT. ...NORTHERN STREAM TROUGH/COLD FRONT CROSSING THE NORTHWEST THROUGH FRI... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THERE ARE ONLY MINOR TIMING DIFFERENCES WITH THIS SYSTEM AND ITS ASSOCIATED COLD FRONT...THUS A GENERAL MODEL COMPROMISE IS PREFERRED TO SMOOTH OUT THESE SMALLER SCALE DIFFERENCES. ...SOUTHERN STREAM COMPONENT OF UPPER LEVEL TROUGH OVER THE WEST ON SAT... ...ENERGY EJECTING INTO THE CENTRAL/SOUTHERN PLAINS SUN NIGHT/MON... PREFERENCE: BLEND OF THE 00Z NAM/00Z ECMWF AND 00Z UKMET CONFIDENCE: AVERAGE THE MODELS CLUSTER TOGETHER VERY WELL WITH THE TIMING AND DEPTH OF THE SOUTHERN STREAM TROUGH INITIALLY CROSSING CA ON FRI AND MOVING INTO GREAT BASIN ON SAT. HOWEVER...AFTER ABOUT 36 HOURS...THE 00Z CMC BECOMES SLOWER THAN THE MODEL CONSENSUS WITH ITS EASTWARD PROGRESSION. IN TIME THE 00Z GFS BEGINS TO TREND A BIT STRONGER THAN THE MODEL CONSENSUS AT THE SURFACE AND ALOFT...AND ESPECIALLY BY SUN NIGHT/MON AS THE SYSTEM CROSSES OUT THROUGH THE CENTRAL/SOUTHERN PLAINS. THE LATEST GEFS MEAN AND ECENS MEAN TEND TO FAVOR THE SLIGHTLY WEAKER CONSENSUS BY LATER SUN/MON. WILL SUGGEST LEANING TOWARD A BLEND OF THE 00Z NAM/UKMET AND ECMWF AT THIS TIME WHICH AS A BLEND MOST CLOSELY MATCHES THE MODEL CONSENSUS. ...UPPER TROUGH/COLD FRONT REACHING THE WEST COAST SUN EVENING... PREFERENCE: BLEND OF THE 00Z GFS/00Z UKMET AND 00Z ECMWF CONFIDENCE: AVERAGE THE MODELS BRING THE NEXT UPPER TROUGH AND ASSOCIATED COLD FRONT ACROSS THE WEST COAST BY SUN EVENING WITH THE TROUGH THEN MOVING INLAND ON MON. THE 00Z NAM IS A TAD FASTER WITH THE FRONT VERSUS THE 00Z GLOBAL MODELS AS IT APPROACHES AND ARRIVES ALONG THE WEST COAST. BY LATER SUN AND MON...WITH RESPECT TO THE UPPER TROUGH...THE 00Z NAM AND 00Z CMC BOTH APPEAR TO BE A TAD TOO FAST...WITH PERHAPS THE 00Z ECMWF EDGING A LITTLE TOO SLOW. WILL COMPROMISE BY SUGGESTING A BLEND OF THE 00Z GFS/UKMET AND ECMWF AT THIS POINT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON $$

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