061  
FXUS10 KWNH 230441  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1241 AM EDT WED OCT 23 2019  
 
VALID OCT 23/0000 UTC THRU OCT 26/1200 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
STRONGER SHORTWAVE DROPPING THROUGH ROCKIES; CLOSING OFF ACROSS  
THE SOUTHERN PLAINS  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z ECENS MEAN AND 12Z UKMET BLEND  
CONFIDENCE: BELOW AVERAGE  
 
SHORTWAVE ENERGY CURRENTLY MOVING THROUGH THE CENTRAL/NORTHERN  
ROCKIES WILL APPROACH THE SOUTHWEST U.S. AND SOUTHERN PLAINS LATER  
IN THE WEEK. MODEL SPREAD AND UNCERTAINTY REMAINS EVEN AT DAY 2  
AND DAY 3 WITH RESPECT HOW THE UPPER LEVEL PATTERN EVOLVES. THERE  
HAVE BEEN 2 SCENARIOS ADVERTISED THE LAST SEVERAL DAYS, ONE BEING  
A SLOWER SOLUTION WITH ENERGY PINCHING OFF INTO A CLOSED LOW OVER  
TEXAS OR A FASTER/FLATTER SOLUTION WITH MORE POSITIVE TILTED  
ENERGY MOVING INTO THE SOUTHEAST U.S. AND OHIO VALLEY.  
 
IN THE LAST 24 HOURS, THE NCEP GUIDANCE (SOLUTION 2 ABOVE) HAS  
TRENDED TOWARD THE NON-NCEP GUIDANCE (SLOWER/CLOSED LOW) THOUGH  
THE MODELS STILL HAVE QUITE A BIT OF SPREAD EVEN AT DAY 2/3. THE  
00Z GFS STILL ADVERTISES A FASTER SOLUTION, BUT DOES CLOSE OFF A  
LOW ACROSS THE ARKLATEX REGION WHILE THE NAM CLOSES OFF OVER  
OKLAHOMA (COMPARED TO THE ECMWF/CMC WHICH CLOSE OFF OVER TEXAS).  
THE 12Z UKMET ACTUALLY LIES IN BETWEEN THE TWO SIDES.  
 
THE DETERMINISTIC ECMWF AND CMC MAY BE A BIT AGGRESSIVE AND QUICK  
TO CLOSE OFF THE LOW AND GIVEN SOME OF THE UNCERTAINTY AND SPREAD  
STILL, SOMETHING MORE ALONG THE LINES OF THE ECENS MEAN COULD BE  
USEFUL FOR A BLENDED APPROACH. THIS IS FAVORED ALSO SINCE THERE'S  
BEEN A TREND TOWARD THE ECMWF LIKE SOLUTIONS (AND NOT TOWARD THE  
GFS SOLUTIONS).  
 
SHORTWAVE TROUGHING ACROSS PACIFIC NORTHWEST FRIDAY-SATURDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z GFS AND 12Z ECMWF BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
THE ANOMALOUS RIDGE OVER THE EASTERN PACIFIC AND WESTERN U.S. MID  
TO LATE WEEK WILL BE SHUNTED AND BROKEN DOWN SOME AS ANOTHER  
STRONG SHORTWAVE TROUGH APPROACHES FROM THE GULF OF ALASKA. THERE  
IS FAIRLY GOOD AGREEMENT IN THE 500 MB HEIGHTS AS FAR AS TIMING  
AND GENERAL ORIENTATION AS THE WAVE REACHES THE PACIFIC NORTHWEST.  
THE 12Z UKMET IS NOTICEABLY STRONGER WITH ITS ENERGY AND DIGS THE  
WAVE A BIT FURTHER TO THE SOUTH. THE 12Z CMC HAS A SIMILAR  
SOLUTION BUT NOT AS STRONG. THE GFS/ECMWF/NAM ARE IN FAIRLY GOOD  
AGREEMENT AND WITHIN THE ENSEMBLE SPREAD. AT THE SURFACE, LOW  
PRESSURE QUICKLY TRACKS THROUGH THE CANADIAN ROCKIES AND MOST OF  
THE DETERMINISTIC MODELS HAVE SIMILAR STRENGTH AS IT EMERGES OUT  
IN THE SOUTHERN CANADIAN PRAIRIES. THE TYPICAL BIASES ARE SEEN -  
FAST GFS, SLOWER ECMWF. AS SUCH, THE WPC PREFERENCE IS TO LEAN  
TOWARD A GFS/ECMWF BLEND AT THIS POINT GIVEN THE RELATIVELY GOOD  
AGREEMENT WITH JUST MINOR SPATIAL DETAILS TO SORT OUT IN 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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