408  
FXUS10 KWNH 261847  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
247 PM EDT SAT OCT 26 2019  
 
VALID OCT 26/1200 UTC THRU OCT 30/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
*** NOTE THAT THE 12Z CMC WAS NOT AVAILABLE AT THE TIME OF THIS  
DISCUSSION'S COMPOSITION.  
 
   
..AMPLIFIED TROUGH/CLOSED LOW LIFTING TOWARD THE OH VALLEY
 
   
..POST T.C. OLGA
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM, SO A GENERAL  
MODEL BLEND WILL BE PREFERRED.  
 
...DEEP TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST ON SUNDAY AND  
REACHING THE PLAINS ON MONDAY...  
...WEAK SURFACE WAVE TRACKING ACROSS THE MIDWEST MONDAY NIGHT WITH  
TRAILING COLD FRONT...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON 12Z GFS BLEND  
CONFIDENCE: AVERAGE  
 
DIFFERENCES WITH THE MID-LEVEL TROUGH'S PROGRESSION OUT WEST BEGIN  
TO BECOME MORE SIGNIFICANT EARLY MONDAY WITH TIMING ISSUES  
CONCERNING EJECTION OF THE SHORTWAVE INTO THE CENTRAL PLAINS. THE  
12Z GFS IS FASTEST, AND HAS BEEN WITH SIMILAR SYSTEMS IN THE  
EASTERN PACIFIC RIDGE/WESTERN CONUS TROUGH PATTERN OF LATE.  
ENSEMBLE TRENDS THROUGH TUESDAY MORNING HAVE BEEN SLOWER WITH THE  
GEFS ADJUSTING TOWARD THE MORE CONSISTENT ECMWF ENSEMBLES. PREFER  
TO STAY NEAR THE ECMWF ENSEMBLE MEAN OR PERHAPS A SHADE FASTER  
WHICH IS CLOSE TO A NON 12Z UKMET BLEND OF THE LATEST  
DETERMINISTIC GUIDANCE.  
 
   
..SHORTWAVE/CLIPPER LOW OVER MT/ND BY MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
ANY MODEL DIFFERENCES WITH THIS SYSTEM ARE MINOR ENOUGH TO SUPPORT  
A GENERAL MODEL BLEND.  
 
...CLOSED LOW LIKELY SETTING UP OVER THE INTERMOUNTAIN WEST FOR  
TUESDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 12Z NAM/ECMWF AND 00Z CMC  
CONFIDENCE: AVERAGE  
 
SIMILAR TO PREVIOUS SYSTEMS DIGGING INTO THE WEST THAT WE'VE SEEN  
RECENTLY, THE 12Z GFS IS THE FARTHEST EAST WITH A LIKELY CLOSED  
LOW OVER THE GREAT BASIN ON TUESDAY. TRENDS IN THE GEFS AND GFS  
SUPPORT A SLOWER/MORE WESTWARD SHIFT OVER THE PAST FOUR 12Z/00Z  
CYCLES. CURRENTLY, NEAR THE ECMWF MEAN AND 00Z ECMWF APPEARS LIKE  
THE MOST FAVORABLE POSITION, WITH THE 12Z NAM AND 00Z CMC THE NEXT  
CLOSEST MODELS TO THAT POSITION. THE 12Z UKMET TRENDED WEST FROM  
ITS 00Z RUN BUT IT REMAINS A BIT FARTHER TO THE EAST THAN  
PREFERRED AT THIS TIME VALID TUESDAY EVENING. A 3-WAY BLEND  
BETWEEN THE 12Z ECMWF, 12Z NAM AND 00Z CMC IS PREFERRED AT THIS  
TIME.  
 
   
..POTENTIAL DISTURBANCE IN THE GULF OF MEXICO EARLY NEXT WEEK
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON 12Z UKMET BLEND  
CONFIDENCE: BELOW AVERAGE  
 
THERE IS CURRENTLY AN ENHANCED AREA OF DISTURBED WEATHER SOUTH OF  
CUBA WHICH SOME OF THE MODELS TRACK AROUND THE WESTERN SIDE OF THE  
SUBTROPICAL ATLANTIC RIDGE INTO THE GULF OF MEXICO. DEEP MOISTURE  
IN PLACE WITH THIS AREA OF DISTURBED WEATHER WILL JOIN WITH AN  
AXIS OF HIGH MOISTURE OUT AHEAD OF THE TAIL END OF A COLD FRONT  
WHICH WILL BE CROSSING THE EAST COAST ON SUNDAY. THERE ARE VARYING  
SOLUTIONS SEEN IN THE LATEST DETERMINISTIC GUIDANCE THROUGH  
TUESDAY MORNING WITH THE 12Z UKMET THE MOST DEVELOPED. HOWEVER,  
FOR NOW, THE PREFERENCE WILL BE FOR A NON 12Z UKMET BLEND WHICH  
DOWNPLAYS ANYTHING MORE ORGANIZED IN AGREEMENT WITH THE LATEST  
THINKING FROM THE NHC.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
OTTO  
 

 
 
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