164  
FXUS10 KWNH 241859  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
258 PM EDT SAT AUG 24 2019  
 
VALID AUG 24/1200 UTC THRU AUG 28/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
EXCEPTION(S): UKMET/ECMWF BLEND FL AND OFF CAROLINAS DAYS 2/3.  
NON-UKMET ACROSS NORTHERN TIER DAY 2/3.  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
AVERAGE FOR SURFACE LOW OFF CAROLINAS.  
 
NCEP MODELS GENERALLY REMAINED STRONG THIS FORECAST PERIOD AGAIN  
PROVIDING CONFIDENCE ACROSS MUCH OF THE CONUS. THERE ARE SMALL  
DETAIL DIFFERENCES LINGERING ACROSS THE NORTHERN TIER ON DAY 3,  
WITH THE 24/12Z UKMET A DEVELOPING/DEEPENING A BIT FURTHER SOUTH  
OF A MODEL CONSENSUS BUT REASONABLY CLOSE TO ITS PREVIOUS RUN.  
THE 24/12Z GFS CONTINUED TO TREND TOWARDS A MORE AMPLIFIED  
SOLUTION WITH THE SECONDARY SHORTWAVE CROSSING SW CANADA LATE  
MONDAY TO REINFORCE THE BROADENING CLOSED LOW INTO THE RED RIVER  
VALLEY AND SOUTH CENTRAL CANADA BY 12Z TUESDAY.  
 
AS THE NORTHERN STREAM TROF AMPLIFIES AND DIGS INTO THE LOWER  
MISSISSIPPI RIVER VALLEY AND INTERACTS WITH THE NORTHEASTWARD  
SHIFTING TROPICAL WAVE, THE NAM IS A BIT MORE SEPARATED AND  
STRONGER WITH EACH FEATURE (TYPICAL OF BIAS). THIS DELAYS ITS  
EASTWARD PROGRESSION ACROSS THE GULF COAST STATES RELATIVE TO THE  
GFS/ECMWF/CMC.  
 
THE 24/12Z GFS CONTINUES THE SHORT-TERM TREND OF A MORE  
EASTWARD/DOWNSTREAM SOLUTION WITH REGARD TO THE PLACEMENT OF THE  
SURFACE WAVE MOVING OUT OF FL INTO THE GULF STREAM OFF THE  
CAROLINA COAST SUN INTO MONDAY. LIKE THE 24/12Z CMC, THE 24/12Z  
GFS WAS WEAKER THAN THE 24/12Z ECMWF AND UKMET. STILL THINK THAT  
THE ECMWF AND UKMET WERE TOO STRONG/DEEP BUT AGREE WITH THE  
PREVIOUS SHIFT FOR A TONED-DOWN VERSION OF THEIR COMPROMISE DEPTH  
OVER OTHER GUIDANCE BLENDS. THE 24/12Z NAM IS NOW CLEARLY THE  
SLOWEST IN THE ENVELOPE OF SOLUTIONS.  
 
SAW LITTLE REASON TO MAKE CHANGES TO THE PREFERENCE WITH RESPECT  
TO TS IVO IN THE DAY 2/3 PERIOD. THIS IS WHEN THE SURFACE CYCLONE  
WILL BE WEAKENING/BECOMING SHALLOW, SO STEERING FLOW WILL BE  
HIGHLY DETERMINED BY REMAINING CONVECTION/DEPTH. WILL CONTINUE TO  
FAVOR THE 24/12Z GFS SOLUTION WITH RESPECT TO MOISTURE TRANSPORT  
INTO THE DESERT SOUTHWEST AND GIVEN ITS TRACK RECORD OVER THE LAST  
DAY OR SO.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
BANN  
 

 
 
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