499   
FXUS10 KWNH 131639  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1138 AM EST WED NOV 13 2019  
  
VALID NOV 13/1200 UTC THRU NOV 17/0000 UTC  
  
..SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..SHORTWAVE CROSSING THE PLAINS/MIDWEST  
   
..CLOSED LOW DEVELOPMENT OVER THE SOUTHEAST  
   
..CYCLOGENESIS OFF THE SOUTHEAST COAST  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...THROUGH 36 HOURS  
            12Z GFS...AFTER 36 HOURS  
CONFIDENCE: ABOVE AVERAGE...BECOMING BELOW AVERAGE AFTER 36 HOURS  
  
A SHORTWAVE WHICH IS CURRENTLY CROSSING PORTIONS OF THE PLAINS AND  
MIDWEST WILL BEGIN TO SEPARATE OUT FROM THE WESTERLIES AND DIG  
DOWN ACROSS THE LOWER MS AND TN VALLEYS ON THURSDAY. AS THIS  
ENERGY DROPS SOUTHEAST ACROSS THE GULF COAST STATES, IT SHOULD  
INTERACT WITH AND CAPTURE ENERGY ASSOCIATED WITH AN EJECTING  
SOUTHERN STREAM CLOSED LOW CROSSING FROM MEXICO THROUGH SOUTH  
TEXAS AND THE WESTERN GULF OF MEXICO. THE RESULT OF THIS  
INTERACTION WILL ULTIMATELY BE A CLOSED LOW OVER THE SOUTHEAST BY  
FRIDAY, WITH COASTAL CYCLOGENESIS TAKING PLACE JUST SOUTHEAST OF  
THE CAROLINAS.  
   
THE 12Z NAM AGAIN BECOMES STRONGER THAN THE GLOBAL MODELS WITH THE  
CLOSED LOW EVOLUTION ACROSS THE SOUTHEAST AND THEN OFFSHORE GOING  
THROUGH FRIDAY AND SATURDAY. THE NAM IS AN OUTLIER SOLUTION WITH A  
LEAD SURFACE LOW THAT DEVELOPS NEAR THE NC OUTER BANKS BY EARLY  
FRIDAY WHICH THEN LIFTS NORTHEAST UP ALONG A FRONTAL ZONE. THE  
ENTIRE GLOBAL MODEL SUITE FOCUSES THE MAIN AREA OF CYCLOGENESIS  
FARTHER SOUTH AND OFFSHORE OF SC BY LATE FRIDAY, ALTHOUGH  
EVENTUALLY THE NAM DOES DEVELOP A NEW AREA OF LOW PRESSURE IN THE  
AREA FRIDAY NIGHT THROUGH SATURDAY, WITH ALL OF THE MODELS AT  
LEAST AGREEING ON THERE BEING A RATHER STRONG AREA OF LOW PRESSURE  
SOUTHEAST OF THE CAROLINAS ON SATURDAY. REGARDING THE GLOBAL  
MODELS, THE 00Z ECMWF APPEARS TO BE TOO SLOW WITH ITS HEIGHT FALL  
PROGRESSION, AND THE 00Z CMC APPEARS TO BE TOO WEAK. THE 12Z GFS  
IS VERY CLOSE TO THE MULTI-MODEL CONSENSUS, WITH THE 00Z UKMET  
JUST A LITTLE EAST OF THE GFS WITH THE SURFACE LOW EVOLUTION. THE  
ENSEMBLE MEANS ARE SPLIT WITH TIMING AS THE ECENS MEAN IS ON THE  
SLOW SIDE OF THE GUIDANCE AND THE GEFS MEAN FASTER, ALTHOUGH THE  
LATEST GFS IS NOT AS PROGRESSIVE AS THE GEFS MEAN. BASED ON THE  
LATEST MODEL CLUSTERING AND ENSEMBLE SPREAD, A GENERAL MODEL BLEND  
WILL BE PREFERRED THROUGH 36 HOURS, FOLLOWED BY A SOLUTION TOWARD  
THE GFS THEREAFTER, ALTHOUGH CONFIDENCE IS LIMITED IN TIME GIVEN  
THE RATHER BROAD SPREAD SEEN WITH THE SURFACE LOW EVOLUTION LATE  
IN THE PERIOD.  
  
   
..STRONG NORTHERN STREAM TROUGH BRUSHING THE NORTHEAST BY FRI  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS  
            NON-NAM BLEND...AFTER 60 HOURS  
CONFIDENCE: ABOVE AVERAGE  
  
THE MODELS PLACE A STRONG NORTHERN STREAM CLOSED LOW DOWN OVER  
PORTIONS OF QUEBEC BY FRIDAY, WITH HEIGHT FALLS BRUSHING PORTIONS  
OF THE NORTHEAST. THE MODELS SHOW GOOD OVERALL AGREEMENT WITH THIS  
SYSTEM THROUGH 60 HOURS, WITH THE 12Z NAM THEN BECOMING A LITTLE  
SLOWER/DEEPER THAN THE GLOBAL MODELS AS THE ENERGY BEGINS TO PULL  
AWAY ON SATURDAY THROUGH THE CANADIAN MARITIMES. WILL PREFER A  
GENERAL MODEL BLEND THROUGH 60 HOURS, AND A NON-NAM BLEND  
THEREAFTER.  
  
   
..MID-LEVEL SHORTWAVES APPROACHING THE WEST COAST ON THURS  
   
..ENERGY DIGGING ACROSS THE INTERMOUNTAIN WEST FRI/SAT  
   
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
PREFERENCE: BLEND OF THE 12Z NAM/00Z CMC AND 00Z ECMWF  
CONFIDENCE: AVERAGE   
   
A RELATIVELY WEAK MID-LEVEL SHORTWAVE IS EXPECTED TO APPROACH THE  
WEST COAST EARLY ON THURSDAY WHILE A SECOND SHORTWAVE FARTHER  
NORTH AIMS TOWARD VANCOUVER ISLAND AND SOUTHERN BRITISH COLUMBIA  
BY EARLY FRIDAY. THE INITIAL SHORTWAVE SHOULD DAMPEN OUT, BUT THE  
SECOND SHORTWAVE FARTHER NORTH IS EXPECTED TO DROP SOUTHEAST DOWN  
ACROSS THE INTERMOUNTAIN WEST AND BEGIN TO AMPLIFY THROUGH  
SATURDAY. THE 00Z UKMET BECOMES THE FASTEST SOLUTION WITH THE  
AMPLIFYING TROUGH, WITH THE 12Z GFS THE SLOWEST. THE 12Z NAM, 00Z  
ECMWF AND 00Z CMC SPLIT THE DIFFERENCE BETWEEN CAMPS AND ACTUALLY  
CLUSTER TOGETHER RATHER WELL, SO A BLEND OF THESE SOLUTIONS WILL  
BE PREFERRED.  
  
   
..CLOSED LOW DEVELOPMENT OFFSHORE SOUTHERN CALIFORNIA ON FRI  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
  
ADDITIONAL SHORTWAVE ENERGY APPROACHING CALIFORNIA LATE THURSDAY  
WILL BREAK AWAY AND DIG SOUTHEAST TO OFFSHORE SOUTHERN CALIFORNIA  
ON FRIDAY, WITH THE GUIDANCE SUPPORTING A WEAK CLOSED LOW  
EVOLUTION THAT DROPS DOWN TO WEST OF THE BAJA PENINSULA BY  
SATURDAY. THE 12Z NAM ENDS UP ON THE SOUTH SIDE OF THE MODEL SUITE  
BY THE END OF THE PERIOD. THE ENSEMBLE MEANS FAVOR THE NON-NAM  
GUIDANCE, SO A NON-NAM BLEND WILL BE PREFERRED.  
  
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
ORRISON  
  
  
 
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