MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1218 PM EDT SUN OCT 04 2015 VALID OCT 04/1200 UTC THRU OCT 08/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS ...SOUTHEASTERN U.S. CLOSED LOW... PREFERENCE: GENERAL MODEL COMPROMISE THROUGH 48 HOURS NON-NAM CONSENSUS...AFTER 48 HOURS CONFIDENCE: ABOVE AVERAGE AN IMPRESSIVE CLOSED UPPER LEVEL LOW CURRENTLY OVER THE SOUTHEAST U.S. CONTINUES TO MOVE VERY SLOWLY TOWARDS THE EAST. OVER THE NEXT COUPLE OF DAYS...THIS ENERGY WILL ADVANCE EAST OFF THE SOUTHEAST COASTLINE AND ALLOW A FRONTAL ZONE ALONG THE SOUTHERN MID-ATLANTIC COAST TO GRADUALLY SHIFT OUT TO SEA ALONG WITH A WAVE OF LOW PRESSURE ALONG IT. THE MODELS ARE IN VERY GOOD AGREEMENT THROUGH ABOUT 48 HOURS...BUT THEREAFTER THE 12Z NAM BECOMES A STRONGER OUTLIER SOLUTION. SO...A GENERAL MODEL COMPROMISE WILL BE PREFERRED THROUGH 48 HOURS...WITH A NON-NAM CONSENSUS THEREAFTER. ...SOUTHWESTERN U.S. CLOSED LOW... PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF AND 00Z UKMET CONFIDENCE: AVERAGE A RELATIVELY COMPACT UPPER LEVEL LOW DIGGING TOWARD SOUTHERN CA WILL SWING EAST ACROSS THE FOUR CORNERS REGION THROUGH TUES...AND TOWARD THE SOUTHERN HIGH PLAINS ON WED. THE GUIDANCE IS IN BETTER AGREEMENT THAN YESTERDAY WITH THE EVOLUTION OF THIS...BUT THE 00Z ECMWF IS STILL JUST A LITTLE SOUTH OF THE GLOBAL MODELS CONSENSUS AFTER 36 HOURS. THE 12Z NAM AND 00Z CMC ARE A LITTLE NORTH OF THE SAME CONSENSUS. THE 12Z GFS AND 00Z UKMET SPLIT THE DIFFERENCE...BUT TEND TO LEAN A LITTLE CLOSER TO THE ECMWF OVERALL. WILL PREFER A BLEND OF THE 12Z GFS/00Z ECMWF AND 00Z UKMET AT THIS POINT. ...SHORTWAVE TROUGH CROSSING THE NORTHERN PLAINS EARLY IN THE WEEK... PREFERENCE: GENERAL MODEL COMPROMISE CONFIDENCE: ABOVE AVERAGE THE MODELS SHOW A NORTHERN STREAM SHORTWAVE TROUGH CLIPPING THE NORTHERN PLAINS REGION LATER TODAY THROUGH MON. THE GUIDANCE REMAINS IN VERY GOOD AGREEMENT WITH THIS SYSTEM...AND THUS A GENERAL MODEL COMPROMISE CAN BE USED. ...SHORTWAVE TROUGH DIGGING TOWARD THE NORTHERN PLAINS BY WED... ...ASSOCIATED CLIPPER-TYPE SURFACE LOW... PREFERENCE: BLEND OF THE 00Z ECMWF AND 00Z UKMET CONFIDENCE: AVERAGE THE MODELS ADVERTISE ANOTHER SHORTWAVE TROUGH DIGGING SOMEWHAT INTO THE NORTHERN PLAINS BY MIDWEEK ALONG WITH A CLIPPER-TYPE SURFACE LOW. THE 12Z GFS IS THE MOST PROGRESSIVE WITH THIS SYSTEM. THE 00Z CMC WAS THE SLOWEST SOLUTION AT LEAST ALOFT...ALTHOUGH ITS SURFACE LOW EVOLUTION WAS VERY CLOSE TO THE MULTI-MODEL CONSENSUS. THE 12Z NAM/00Z ECMWF AND 00Z UKMET SPLIT THE DIFFERENCE ALOFT AND CLUSTER TOGETHER RATHER WELL...ALTHOUGH THE 12Z NAM APPEARS TO BE A LITTLE TOO STRONG ON WED WITH ITS SURFACE LOW OVER ND. WILL PREFER A BLEND OF THE 00Z ECMWF AND 00Z UKMET AT THIS POINT AS A RESULT. www.wpc.ncep.noaa.gov/html/model2.shtml... www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... ORRISON