023  
FXUS10 KWNH 270631  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
230 AM EDT SUN OCT 27 2019  
 
VALID OCT 27/0000 UTC THRU OCT 30/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..TROUGH/CLOSED LOW CURRENTLY OVER THE OH VALLEY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE LATEST MODEL GUIDANCE SHOWS THE UPPER TROUGH AND ASSOCIATED  
LOW CENTER OVER THE OH VALLEY CROSSING THROUGH THE LOWER GREAT  
REGION EARLY SUNDAY. THE ENERGY THOUGH WILL BE ENCOUNTERING  
INCREASINGLY CONFLUENT DOWNSTREAM FLOW ALOFT AND THE SYSTEM WILL  
WEAKEN SUBSTANTIALLY LATE SUNDAY AS IT REACHES THE NORTHEAST. AS  
THE ATTENDANT COLD FRONT REACHES THE EAST COAST, THE ORIGINAL LOW  
CENTER WILL DAMPEN OUT IN FAVOR OF A NEW AREA OF CYCLOGENESIS NEAR  
SOUTHERN NEW ENGLAND. THIS LOW CENTER WILL MOVE EAST AND OFFSHORE  
MONDAY AS THE REMNANT ENERGY ALOFT SHIFTS EAST TOWARD THE WESTERN  
ATLANTIC AND CONTINUES TO WEAKEN. ALL OF THE MODELS ARE IN GOOD  
AGREEMENT NOW WITH THE DETAILS OF THE MASS FIELD EVOLUTION, AND SO  
A GENERAL MODEL BLEND WILL BE PREFERRED.  
 
   
..DEEP TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST/PLAINS
 
   
..CLOSED LOW EVOLUTION OVER THE FOUR CORNERS BY WEDNESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z UKMET/ECMWF  
CONFIDENCE: ABOVE AVERAGE  
 
A STRONG DEEP LAYER RIDGE OVER THE GULF OF AK THIS WEEKEND WILL  
SHIFT TOWARD NORTHWEST CANADA EARLY NEXT WEEK WHICH WILL ALLOW  
SHORTWAVE ENERGY TO DIG SOUTH ACROSS SOUTHWEST CANADA AND THEN  
INTO INTERMOUNTAIN WEST AND HIGH PLAINS THROUGH THE PERIOD,  
LEADING TO THE DEVELOPMENT OF A DEEP LONGWAVE TROUGH OVER THE  
INTERMOUNTAIN WEST AND PLAINS BY TUESDAY. AS ADDITIONAL ENERGY  
DIGS INTO THE BACKSIDE OF THE TROUGH ON WEDNESDAY, THERE SHOULD BE  
A CLOSED LOW EVOLUTION THAT SETTLES DOWN TOWARD THE FOUR CORNERS  
REGION. GRADUALLY THE 00Z NAM BECOMES A BIT STRONGER THAN ALL OF  
THE GLOBAL MODELS AS THE CLOSED LOW EVOLUTION TAKES SHAPE. AND BY  
THE END OF THE PERIOD, THE 00Z GFS BECOMES THE MOST PROGRESSIVE  
SOLUTION IN PIVOTING THE ENERGY FARTHER EAST ACROSS CO, WHEREAS  
THE REMAINING GUIDANCE HAS THE CLOSED LOW OVER UT. THE BETTER  
MODEL CLUSTERING RESIDES WITH THE 00Z NON-NCEP GUIDANCE, LED  
ESPECIALLY BY THE UKMET AND ECMWF. SO, A BLEND OF THE UKMET AND  
ECMWF WILL BE PREFERRED WHICH IS STRONGLY SUPPORTED BY THE LATEST  
GEFS MEAN AND ECENS MEAN AS WELL.  
 
   
..SHORTWAVE/CLIPPER LOW OVER MT/ND BY MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
AS THE HIGHLY AMPLIFIED DEEP LAYER FLOW PATTERN EVOLVES ACROSS  
NORTH AMERICA EARLY NEXT WEEK, THE GUIDANCE FAVORS A VIGOROUS  
SHORTWAVE/JET-STREAK DIVING SOUTHEAST TOWARD THE NORTHERN HIGH  
PLAINS ON MONDAY WHICH WILL DRIVE A CLIPPER LOW AND REINFORCING  
COLD FRONT SOUTHEAST ACROSS MT/ND. THE MODELS ARE IN GOOD  
AGREEMENT WITH THIS FEATURE, SO A GENERAL MODEL BLEND WILL BE  
PREFERRED.  
 
   
..SURFACE COLD FRONT OVER THE LOWER/MID MS VALLEY BY TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS/ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
AS THE DEEP LONGWAVE TROUGH EJECTS OUT OVER THE PLAINS SUNDAY AND  
MONDAY, A COLD FRONT WILL SETTLE WELL SOUTH AND EAST, AND WILL BE  
APPROACHING THE LOWER/MIDDLE MS VALLEY REGION LATE MONDAY AND  
TUESDAY. SOME INCREASE IN MODEL SPREAD WITH THE TIMING OF THE  
FRONT AND THE DETAILS OF A WAVE OF LOW PRESSURE RIDING NORTHEAST  
UP ALONG IT IS SEEN BY EARLY TUESDAY. MOST NOTABLY, THE 00Z UKMET  
TENDS TO BE THE SLOWEST SOLUTION WITH THE BOUNDARY AS IT CROSSES  
THE MS VALLEY AND APPROACHES THE OH VALLEY. WITH RESPECT TO THE  
FRONTAL WAVE, THE 00Z NAM IS MOST PROGRESSIVE WITH IT. IN GENERAL,  
THE 00Z GFS AND 00Z ECMWF TEND TO CLUSTER TOGETHER RATHER WELL AND  
HAVE FAVORABLE SUPPORT FROM THEIR RESPECTIVE ENSEMBLE SUITES, SO A  
BLEND OF THE GFS AND ECMWF WILL BE PREFERRED FOR NOW.  
 
   
..POTENTIAL DISTURBANCE IN THE GULF OF MEXICO EARLY NEXT WEEK
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND  
CONFIDENCE: AVERAGE  
 
THERE IS CURRENTLY AN AREA OF DISTURBED WEATHER SOUTH OF CUBA  
WHICH SOME OF THE MODELS TRACK AROUND THE WESTERN SIDE OF THE  
SUBTROPICAL ATLANTIC RIDGE AND INTO THE GULF OF MEXICO. THE MODELS  
ARE IN SUFFICIENTLY GOOD ENOUGH AGREEMENT WITH THE 00Z CYCLE TO  
SUPPORT A GENERAL MODEL BLEND.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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