138  
FXUS10 KWNH 260641  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
241 AM EDT SAT OCT 26 2019  
 
VALID OCT 26/0000 UTC THRU OCT 29/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..SHORTWAVE TROUGH CROSSING THE NORTHEAST ON SATURDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
A SHORTWAVE TROUGH CURRENTLY CLIPPING THE GREAT LAKES WILL ADVANCE  
EAST ACROSS THE NORTHEAST EARLY SATURDAY MORNING AND THEN EXIT  
THROUGH THE CANADIAN MARITIMES LATE IN THE DAY. ANY MODEL  
DIFFERENCES WITH THIS SYSTEM ARE MINOR AND THEREFORE A GENERAL  
MODEL BLEND WILL BE PREFERRED.  
 
   
..AMPLIFIED TROUGH/CLOSED LOW LIFTING TOWARD THE OH VALLEY
 
   
..POST T.C. OLGA
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
EFFECTIVE AT 03Z, T.S. OLGA HAS MERGED WITH THE STRONG COLD FRONT  
ADVANCING EAST ACROSS THE LOWER MS VALLEY AND IS NOW AN  
EXTRATROPICAL CYCLONE POSITIONED 170 MILES SOUTH-SOUTHEAST OF LAKE  
CHARLES, LA. THE LATEST MODEL GUIDANCE SHOWS THE LOW CENTER  
LIFTING NORTHEAST AND INLAND BY EARLY SATURDAY MORNING OVER  
SOUTH-CENTRAL LA WITH THE SYSTEM THEN RAPIDLY LIFTING  
NORTH-NORTHEAST TOWARD THE OH VALLEY LATER IN THE AFTERNOON AND  
ACROSS THE LOWER GREAT LAKES REGION BY EARLY SUNDAY. THE  
SUPPORTING UPPER TROUGH WILL BE ENCOUNTERING INCREASINGLY  
CONFLUENT DOWNSTREAM FLOW ALOFT WITH TIME AND THE SYSTEM WILL  
WEAKEN SUBSTANTIALLY LATE SUNDAY AS IT REACHES THE NORTHEAST. AS  
THE ATTENDANT COLD FRONT REACHES THE EAST COAST LATE SUNDAY, 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
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GEFS/12Z ECENS MEAN  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
A STRONG DEEP LAYER RIDGE IS FORECAST TO EVOLVE OVER THE GULF OF  
AK THIS WEEKEND AND 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. THE 00Z NON-NCEP  
MODELS ARE ALL A LITTLE SLOWER THAN THE 00Z NAM AND 00Z GFS WITH  
THE INITIAL SURGE OF ENERGY THAT PIVOTS ACROSS THE FOUR CORNERS  
REGION SUNDAY THROUGH MONDAY. THE LATEST GEFS MEAN AND ECENS MEAN  
SUPPORT A SOLUTION TOWARD THE MODESTLY MORE PROGRESSIVE CAMP, BUT  
IT SHOULD BE NOTED THAT THE ECMWF DID TREND SLOWER AND AWAY FROM  
THE NAM/GFS CAMP COMPARED TO ITS PREVIOUS RUN AND IS NOW ALIGNED  
WITH THE LATEST UKMET/CMC SOLUTIONS. TOWARD THE END OF THE PERIOD  
WITH THE DETAILS OF THE LONGWAVE TROUGH, THE NAM APPEARS TO BE  
PERHAPS SLIGHTLY TOO DEEP OVER THE ROCKIES AND IMMEDIATE HIGH  
PLAINS WITH THE ENERGY. ALSO, THE 00Z NON-NCEP MODEL SUITE VIA THE  
UKMET, CMC AND ECMWF ARE ALL A TAD SLOWER THAN THE NAM AND GFS  
WITH THE CORE OF HEIGHT FALLS/JET ENERGY DIGGING SOUTH ACROSS THE  
NORTHERN ROCKIES. A BLEND OF THE LATEST GEFS MEAN AND ECENS MEAN  
WILL BE PREFERRED TO ACCOUNT FOR THE RELATIVELY MODEST MODEL  
SPREAD.  
 
   
..SHORTWAVE/CLIPPER LOW OVER MT/ND BY MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY 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 LATEST NON-NCEP MODEL SUITE  
DID TREND A TAD SLOWER AND IS AGAIN A LITTLE SLOWER THAN THE NAM  
AND GFS, BUT FOR NOW, A GENERAL MODEL BLEND WILL CONTINUE TO BE  
PREFERRED.  
 
   
..SURFACE COLD FRONT OVER THE LOWER/MID MS VALLEY BY TUESDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GEFS/12Z ECENS MEAN  
CONFIDENCE: 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. SPREAD INCREASES WITH THE TIMING OF THE FRONT AS THE 00Z  
GFS BECOMES MORE PROGRESSIVE THAN THE REMAINING GUIDANCE.  
MEANWHILE, THE 00Z UKMET BECOMES THE SLOWEST. THERE IS ALSO SOME  
SUPPORT FOR A WEAK WAVE OF LOW PRESSURE TO DEVELOP ALONG THE FRONT  
AND LIFT UP ACROSS THE GREAT LAKES REGION BY THE END OF THE  
PERIOD. THE BETTER MODEL CLUSTERING WITH THE SURFACE FRONT AND THE  
SURFACE WAVE IS WITH THE LATEST GEFS MEAN AND ECENS MEAN, SO A  
BLEND OF THESE SOLUTIONS WILL BE PREFERRED.  
 
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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