528  
FXUS10 KWNH 281915  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
314 PM EDT MON OCT 28 2019  
 
VALID OCT 28/1200 UTC THRU NOV 01/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..MID-LEVEL TROUGH EJECTING INTO THE CENTRAL PLAINS  
   
..SHORTWAVE/CLIPPER LOW OVER MT/ND THIS EVENING  
   
..SURFACE COLD FRONT OVER THE LOWER/MID MS VALLEY BY TUESDAY  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
SHORTWAVE ENERGY CURRENTLY OVER THE CENTRAL ROCKIES WILL EJECT OUT  
INTO THE CENTRAL PLAINS AND ADVANCE NORTHEASTWARD TOWARD THE UPPER  
MIDWEST THE NEXT 24 HOURS. THERE IS ABOVE AVERAGE MODEL AGREEMENT  
AND CONTINUITY SUCH THAT A GENERAL MODEL BLEND WILL SUFFICE.  
 
   
..POWERFUL CLOSED LOW OVER THE INTERMOUNTAIN WEST BY TUESDAY  
   
..ENERGY ADVANCING EAST ACROSS THE PLAINS WEDNESDAY  
   
..COLD FRONT/SURFACE WAVE NEAR OH/TN VALLEYS BY THURSDAY  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE ECMWF/ECENS MEAN  
CONFIDENCE: AVERAGE TO SLIGHTLY BELOW AVERAGE  
 
19Z UPDATE: NO SIGNIFICANT CHANGES NOTED WITH THE REST OF THE 12Z  
GUIDANCE NOW AVAILABLE. THE GFS REMAINS A FASTER OUTLIER WITH THE  
TROUGH AXIS ON DAY 2/3 AND THE NAM IS CONSIDERABLY SLOWER ON DAY  
3. THE ECMWF AND TO SOME DEGREE THE UKMET/CMC OFFER A COMPROMISE  
SOLUTION. AT THE SURFACE, THE CMC TAKES THE LOW WELL NORTHEAST  
(NORTH OF MAINE) WHILE THE REST OF THE GUIDANCE SEEMS TO BE  
CLUSTERING ON AN EASTERN GREAT LAKES POSITION BY 01.00Z. WITH THIS  
IN MIND, THE PREFERENCE WILL REMAIN THE SAME FOR A ECMWF/ECENS  
MEAN BLEND, ESPECIALLY DAY 2/3 WHEN CONFIDENCE IS BELOW AVERAGE.  
 
---PREVIOUS DISCUSSION---  
WITH STRONG RIDGING ALOFT ACROSS THE EASTERN PACIFIC, SHORTWAVE  
ENERGY DROPPING SOUTH INTO THE NORTHERN/CENTRAL ROCKIES TUESDAY  
WILL DIG VIGOROUSLY AND EVENTUALLY CLOSE OFF ACROSS COLORADO.  
THROUGH 48 HOURS, MODEL AGREEMENT IS AVERAGE EXCEPT FOR THE LATEST  
GFS, WHICH CONTINUES TO BE TOO FAST/PROGRESSIVE WITH THE OVERALL  
EVOLUTION OF THE SYSTEM. ITS DIFFERENCES ARE LESS THAN PREVIOUS  
RUNS BUT STILL SIGNIFICANT ENOUGH TO BE EXCLUDED FROM THE FORECAST  
PREFERENCE AT THIS TIME.  
 
THE SYSTEM THEN SLOWLY EJECTS INTO THE CENTRAL PLAINS THROUGH  
THURSDAY WITH THE GFS REMAINING AHEAD OF THE REST OF THE  
DETERMINISTIC GUIDANCE AND ENSEMBLE MEANS. SEVERAL WAVES OF LOW  
PRESSURE ARE FORECAST TO DEVELOP AND MOVE THROUGH THE TN/OH  
VALLEYS LATE WEEK EVENTUALLY CONSOLIDATING INTO A DEEPER SYSTEM  
OVER THE GREAT LAKES BY THE END OF THE WEEK. THE NAM BECOMES TOO  
SLOW BY DAY 3 AND IS NOT AS USABLE THEN. THERE IS FAIRLY GOOD  
AGREEMENT WITH THE LATEST ECMWF AND ECENS MEAN AND PERHAPS EVEN  
SOME UTILITY IN THE GEFS MEAN AS WELL. CONFIDENCE BECOMES DEGRADED  
THOUGH BY THE END OF THE PERIOD GIVEN THE OVERALL DETERMINISTIC  
MODEL SPREAD.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
TAYLOR  
 
 
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