290  
FXUS10 KWNH 261922  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
321 PM EDT MON AUG 26 2019  
 
VALID AUG 26/1200 UTC THRU AUG 30/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
 
---19Z UPDATE---  
NO MAJOR CHANGES MADE TO THE PREFERENCE. THE QPF IN THE SOUTHERN  
PLAINS ON DAY 2 WAS TRENDED CLOSER TO THE AVAILABLE HI-RES MODEL  
GUIDANCE.  
 
---PREVIOUS DISCUSSION---  
MODELS ARE IN FAIRLY GOOD AGREEMENT OVER THE NEXT FEW DAYS WITH  
THEIR DEPICTIONS OF THE MASS FIELDS, WITH MOST DETERMINISTIC  
MODELS WELL WITHIN THE ENVELOPE OF ENSEMBLE SPREAD. THE NOTABLE  
EXCEPTION SEEMS TO BE WITH THE 12Z NAM, WHICH HAS A MUCH STRONGER  
WAVE ROUNDING THE BASE OF THE GREAT LAKES TROUGH ON WEDNESDAY,  
LEADING TO A SURFACE LOW MUCH CLOSER TO THE NORTHEAST COAST ON  
THURSDAY. THIS YIELDS HEAVIER QPF ACROSS MUCH OF NEW ENGLAND.  
GIVEN THE LACK OF ENSEMBLE SUPPORT, THE PREFERENCE IS FOR A  
NON-NAM BLEND OVERALL, BASED ON THE MASS FIELDS. THIS MAY AFFECT  
THE NBM QPF OVER THE REGION.  
 
OTHERWISE, THERE ARE CONSIDERABLE QPF DIFFERENCES ON DAY 2 AND DAY  
3 OVER THE SOUTHERN PLAINS, WITH GLOBAL MODELS CONCENTRATING  
RAINFALL NEAR THE RED RIVER FROM TUESDAY NIGHT INTO WEDNESDAY,  
WHILE HI-RES MODELS ARE CONSIDERABLY FURTHER SOUTHWEST. THE  
PREFERENCE HERE WILL BE TO STRIKE A BALANCE, AS CONVECTIVE  
RAINFALL OFTEN ENDS UP SLIGHTLY FURTHER SOUTH THAN GLOBAL MODELS  
WOULD INDICATE. HOWEVER, HI-RES MODELS ARE NOT EXACTLY CONSISTENT  
ENOUGH TO PINPOINT A LOCATION AND COULD BE TOO FAR SOUTH GIVEN THE  
ROBUST SIGNAL IN GLOBAL MODELS. THESE DIFFERENCES MAY LIKEWISE  
AFFECT NBM QPF GIVEN THE INCLUSION OF THE NAM NEST IN THE DAY 2-3  
TIME FRAME.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
LAMERS  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page