MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1257 AM EDT TUE AUG 19 2014 VALID AUG 19/0000 UTC THRU AUG 22/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z GFS/NAM INITIALIZATION WITH PRELIMINARY MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INITIALIZATION ERRORS WITH THE NAM/GFS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. DEEP-LAYERED CYCLONE MOVING TOWARDS THE DESERT SOUTHWEST ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-CANADIAN COMPROMISE CONFIDENCE: AVERAGE THE NON-GFS GUIDANCE HAS SHOWN SOME SIGNIFICANT FLIP-FLOPPING IN THEIR FORECASTS CONCERNING THIS SYSTEM, LOWERING CONFIDENCE IN ANY NON-GFS SOLUTION RIGHT OFF THE BAT. TO BE FAIR, THE CYCLONE IS DROPPING TOWARDS A COL POINT IN THE MID-LEVEL FLOW, WHICH NORMALLY LEADS TO GREATER THAN AVERAGE UNCERTAINTY, MODEL GUIDANCE OR OTHERWISE. SPEAKING OF NON-GFS GUIDANCE, THE 12Z CANADIAN IS NOW THE SLOWEST/MOST WESTERLY SOLUTION AMONGST THE GUIDANCE THU/FRI -- ITS USUAL BIAS. A NON-CANADIAN COMPROMISE IS PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING THE POOR DAY-TO-DAY CONTINUITY SEEN IN THE NON-GFS GUIDANCE. TROUGH MOVING THROUGH THE NORTHERN CONTINENTAL DIVIDE LEADING SHORTWAVE MOVING THROUGH THE DAKOTAS WED/THU ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF COMPROMISE CONFIDENCE: AVERAGE THE 12Z UKMET/12Z CANADIAN ARE WEAKER THAN THE OTHER GUIDANCE, INCLUDING THE 12Z ECMWF/18Z GEFS MEANS, WITH THIS SYSTEM. THE BEST 12Z GLOBAL ENSEMBLE CLUSTERING WITH THIS SYSTEM SUPPORTS THE 00Z GFS/12Z ECMWF SOLUTIONS, WHICH ARE PREFERRED WITH ONLY AVERAGE CONFIDENCE CONSIDERING THE ABOVE AVERAGE SPREAD SEEN IN THE DETERMINISTIC AND 12Z GLOBAL ENSEMBLE GUIDANCE. SYSTEM MOVING ACROSS THE GREAT LAKES & NORTHEAST SURFACE LOW NEAR THE VIRGINIA CAPES FRIDAY MORNING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-UKMET COMPROMISE CONFIDENCE: ABOVE AVERAGE THIS MID-LEVEL SYSTEM IS EXPECTED TO PROGRESS UNDER THE BASE OF AN INCREASINGLY STRONG AND QUASI-STATIONARY NORTHERN STREAM RIDGE/CLOSED HIGH WITH TIME WHICH SHOULD KEEP IT STRONG AND PROGRESSIVE. THE 12Z UKMET FAILED IN THE STRENGTH DEPARTMENT ALOFT, AND BECAUSE OF THIS, FALLS OUTSIDE THE 12Z GLOBAL ENSEMBLE CLUSTERING BY FRIDAY MORNING WITH THE SURFACE LOW NEAR NC AND THE VIRGINIA CAPES. A NON-UKMET COMPROMISE IS ADVISED HERE WITH ABOVE AVERAGE CONFIDENCE BASED UPON THE SYNOPTIC PATTERN IN WHICH THE SYSTEM IS EMBEDDED. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ROTH