236  
FXUS10 KWNH 200740  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
339 AM EDT SUN OCT 20 2019  
 
VALID OCT 20/0000 UTC THRU OCT 23/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
NORTHERN STREAM SHORTWAVE AND SURFACE CYCLOGENESIS PLAINS/UPPER  
MIDWEST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND; WEIGHTED TOWARD ECMWF/GFS/UKMET  
CONFIDENCE: AVERAGE  
 
07Z UPDATE: NO SIGNIFICANT CHANGES NOTED WITH THE REST OF THE 00Z  
GUIDANCE NOW AVAILABLE - THE 00Z CMC DID TREND A BIT BETTER TOWARD  
THE REST OF THE MODEL CONSENSUS SUCH THAT SOME OF IT CAN BE  
INCORPORATED. THE 00Z ECMWF WAS NOT AS DEEP WITH ITS SURFACE LOW  
OVER MN/WI COMPARED TO ITS 12Z RUN AND IS NOW MORE IN LINE WITH  
THE REST OF THE 00Z GUIDANCE. OVERALL, TRACK AND MINIMUM SLP IS  
FAIRLY CLUSTERED SUCH THAT A GENERAL BLEND CAN BE INCORPORATED.  
 
---PREVIOUS DISCUSSION---  
SHORTWAVE ENERGY CURRENTLY MOVING THROUGH THE NORTHERN ROCKIES  
WILL EJECT OUT INTO THE CENTRAL/NORTHERN PLAINS LATER TODAY. ALL  
OF THE AVAILABLE DETERMINISTIC AND ENSEMBLE GUIDANCE CLOSES OFF  
THE MID-LEVEL LOW AT 500 MB BY 18Z, WITH BETTER CLUSTERING IN THE  
POSITION/AXIS OF THIS TROUGH NOW COMPARED TO THE PREVIOUS MODEL  
CYCLES. AS THE LOW MOVES INTO PORTIONS OF THE DAKOTAS AND  
NEBRASKA, THE CMC QUICKLY FALLS OUT OF FAVOR AS IT IS TOO DEEP/AMP  
FLIED AS WELL AS SLOW AND TO THE SOUTH OF THE MODEL CONSENSUS. ITS  
SOLUTION SHOULD BE DISCARDED. BY 48 HOURS /22.00Z/ THE MID/UPPER  
LEVEL LOW REACHES THE UPPER MISSISSIPPI RIVER VALLEY. AT THE  
SURFACE, CYCLOGENESIS WILL OCCUR ALONG THE NE/SD BORDER WITH A  
SECONDARY LOW EXPECTED TO FORM ACROSS NORTH TEXAS. THE NORTHERN  
LOW WILL BE DOMINANT AT FIRST BUT THEN AS THE SOUTHERN LOW LIFTS  
NORTHEAST, IT WILL BECOME ABSORBED WITH THE STRONGER/NORTHERN LOW  
IN THE VICINITY OF MN/IA/WI. THE ECMWF/NAM DEPICT THE LOW CENTER  
OVER WESTERN WI WHILE THE GFS/UKMET KEEP THE INITIAL LOW TO THE  
WEST DOMINANT. AFTER 48 HOURS ALL THE MODELS DEPICT ONE LOW CENTER  
ACROSS NORTHERN WISCONSIN AS THE WHILE SYSTEM BECOMES  
OCCLUDED/STACKED. FOR MODEL PREFERENCE, THROUGH 22.00Z THE CMC  
SHOULD NOT BE INCLUDED OR CONSIDERED. THEREAFTER, A BLEND OF THE  
ECMWF/GFS/UKMET IS PREFERRED AS CONFIDENCE TRENDS TOWARD AVERAGE.  
 
THIRD FAST MOVING SHORTWAVE ENTERING NORTHERN US ROCKIES/MT HIGH  
PLAINS LATE TUESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE TO SLIGHTLY BELOW AVERAGE  
 
THE 3RD MORE SIGNIFICANT SHORTWAVE, WILL OVER-TOP THE BROAD  
LONGWAVE RIDGE PEAKING AROUND VANCOUVER ISLAND AND SLIP INTO THE  
NORTHERN US ROCKIES AND MT HIGH PLAINS. MODEL GUIDANCE IS IN  
DECENT AGREEMENT WITH VERY LITTLE SPREAD SEEN BETWEEN THE 00Z  
GFS/NAM AND 12Z ECMWF/UKMET/CMC AT 500 MB. AT THE SURFACE, THE NAM  
SURFACE LOW DEPICTION IS FAST, PARTICULARLY ON DAY 3 BUT IS WITH  
THE MODEL SPREAD ENVELOPE, SO IT CAN STILL BE INCORPORATED.  
OVERALL, WILL FAVOR A GENERAL MODEL BLEND GIVEN THE RELATIVELY  
GOOD AGREEMENT.  
 
POST-TROPICAL STORM NESTOR  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS, 12Z ECMWF/UKMET  
CONFIDENCE: AVERAGE TO SLIGHTLY ABOVE AVERAGE  
 
POST-TROPICAL CYCLONE NESTOR HAS LOST ITS NEAR CENTER CONVECTION  
WITH THE LATEST CENTER INLAND ACROSS GEORGIA. THE MOST RECENT  
MODEL GUIDANCE IS IN REASONABLE AGREEMENT THAT THE CENTER WILL  
MOVE TOWARD EASTERN NORTH CAROLINA LATER TODAY AND THEN OFFSHORE  
THE MID-ATLANTIC COAST THIS EVENING. THE SYSTEM THEN WILL SLOW AND  
GRADUALLY DISSIPATE AND/OR BECOME ABSORBED WITHIN TROUGHING OVER  
THE EASTERN CONUS EARLY TO MID NEXT WEEK. AFTER 30-36 HOURS, MODEL  
SPREAD DOES INCREASE REGARDING THE TRACK - WITH THE NAM BEING LEFT  
OF THE MODEL CONSENSUS AND CMC TO THE RIGHT. THE 00Z GFS ALONG  
WITH THE 12Z ECMWF/UKMET IS A REASONABLE CONSENSUS AT THIS TIME.  
 
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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