271  
FXUS10 KWNH 271644  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1144 AM EST MON JAN 27 2020  
 
VALID JAN 27/1200 UTC THRU JAN 31/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
...SHORTWAVE DIVING ACROSS THE PLAINS TO OFF THE NORTH CAROLINA  
COAST TONIGHT...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
GUIDANCE IS IN GOOD AGREEMENT IN SPATIAL AND INTENSITY EVOLUTION  
OF THIS FEATURE AS IT SHEARS OFF TO THE EAST TODAY AND TONIGHT.  
 
...SPLIT FLOW TROUGH CROSSING THE MOUNTAIN WEST TODAY AND REACHING  
THE SOUTHEAST WEDNESDAY NIGHT...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z GFS AND 00Z ECMWF BLEND  
CONFIDENCE: AVERAGE  
 
THE NEW 12Z GFS HAS COME INTO PRETTY GOOD AGREEMENT SYNOPTICALLY  
WITH THE 00Z ECMWF WITH REGARDS TO HOW THE SHORTWAVE ENERGY WITHIN  
THE CENTRAL U.S. TROUGH EVOLVES AS IT MOVES INTO THE SOUTHEASTERN  
PORTION OF THE COUNTRY WEDNESDAY NIGHT INTO THURSDAY. THE 12Z NAM  
HAS THE SAME IDEA INITIALLY, BUT IS OVERALL SLOWER THAN THE BETTER  
CONSENSUS, WHICH EVENTUALLY RESULTS IN A FLATTER, YET MORE  
ENERGETIC WAVE OVER THE SOUTHERN MID ATLANTIC ON THURSDAY. WILL  
LEAN AGAINST THIS SOLUTION AT THIS TIME SINCE THE NAM PRETTY  
QUICKLY BECOMES A SLOW OUTLIER WITH THIS TROUGH EVOLUTION. THE 00Z  
CMC QUICKLY BECOMES AN OUTLIER WITH ITS HANDLING OF THE SHORTWAVE  
ENERGY OVER THE PLAINS BY TUESDAY AFTERNOON. GIVEN HOW QUICK THE  
CMC DEVIATES FROM THE BETTER MODEL CLUSTERING, WOULD NOT RECOMMEND  
USING IT WITH THIS SYSTEM...AND WOULD EXPECT WE WILL SEE THE 12Z  
RUN AT LEAST COME A BIT MORE IN LINE WITH THE GFS/ECMWF IDEA. THE  
00Z UKMET INITIALLY LOOKS SIMILAR TO THE GFS/ECMWF CLUSTER, BUT  
ENDS UP BECOMING FLATTER BY LATER WEDNESDAY INTO THURSDAY OVER THE  
EAST. THERE MAY BE SOME ROOM FOR THE GFS/ECMWF TO BECOME A BIT  
FLATTER, BUT THINK THE UKMET IS LIKELY TOO MUCH SO. THUS AT THIS  
POINT A GFS/ECMWF BLEND SEEMS TO OFFER THE BEST SOLUTION FOR THIS  
SYSTEM.  
 
...PROGRESSIVE UPPER TROUGH OVER THE PACIFIC NORTHWEST AND  
AMPLIFYING INTO THE SOUTHERN PLAINS WEDNESDAY.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
 
YET ANOTHER IN A SERIES OF PACIFIC SHORTWAVE TROUGHS WILL ARRIVE  
ON TUESDAY ACROSS THE PACIFIC NORTHWEST, AND THEN DIG INTO THE  
SOUTHWEST LATER WEDNESDAY INTO THURSDAY. AGREEMENT REMAINS PRETTY  
GOOD ON THE BROAD SCALE. COMPARING THE FULL SUITE OF ENSEMBLES,  
THE 00Z ECWMF REMAINS A BIT FURTHER SOUTH WITH THE ENERGY BY 12Z  
THURSDAY, WITH THE 00Z UKMET ON THE NORTHERN EDGE OF THE FULL  
ENSEMBLE ENVELOPE. HOWEVER NEITHER OF THESE SOLUTIONS ARE  
DIFFERENT ENOUGH TO BE RULED OUT AT THIS POINT. THUS IN GENERAL  
THINK A GENERAL BLEND/CONSENSUS SHOULD WORK OKAY WITH THIS SYSTEM  
FOR THE TIME BEING THROUGH 00Z FRIDAY.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
CHENARD  
 
 
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