522  
FXUS10 KWNH 301942  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
341 PM EDT MON SEP 30 2019  
 
VALID SEP 30/1200 UTC THRU OCT 04/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z FINAL MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..OVERALL PATTERN ACROSS THE CONUS  
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z NON-CMC/NAM BLEND CENTRAL/EAST, NON-GFS ON DAY 3  
ON WEST COAST  
CONFIDENCE: AVERAGE  
 
THE MAIN TWO CONCERNS IN THE NEXT THREE DAYS ARE TIMING OF THE  
TROUGH CURRENTLY OVER THE NORTHWEST CONUS AS IT EJECTS NORTHEAST  
ACROSS THE NORTHERN GREAT PLAINS LATE WEDNESDAY/THE NORTHERN GREAT  
LAKES THURSDAY AND THE NEXT TROUGH DIGGING INTO THE WEST COAST ON  
THURSDAY.  
 
THE 12Z NAM REMAINS THE FASTEST TO EJECT THE TROUGH WITH  
DIFFERENCES APPEARING IN DAY 2 AND CONTINUING TO OUTPACE THE 12Z  
CONSENSUS THROUGH DAY 3, SO IT IS NOT A PART OF THE BLEND. THE 12Z  
CMC IS DEEPER AND SLOWER WITH THE LOW OVER THE NORTHERN GREAT  
LAKES ON DAY 3, SO IT ALSO IS REMOVED.  
 
THE 12Z GFS CONTINUES A LONG TREND IN THE GFS OF HAVING A  
SHALLOWER TROUGH IN THE WEST ON DAY 3 WHICH RESULTS IN  
PRECIPITATION LIMITED FARTHER NORTH (NOTICEABLE OVER OR) COMPARED  
TO THE 12Z CONSENSUS WHICH IS CONSISTENT AMONG ALL OTHER GUIDANCE.  
THEREFORE, A NON-GFS GENERAL MODEL BLEND IS RECOMMENDED IN THE  
WEST FOR DAY 3.  
 
THE 12Z ECMWF AND UKMET SHARE STRONG SIMILARITIES IN HOW THEY  
ADVECT THE STRONG SHORTWAVE TROUGH AS IT ROUNDS AND TOPS OFF  
EASTERN CONUS RIDGE AS WELL AS A MORE AMPLIFIED TROUGH DOWN THE  
WEST COAST ON THURSDAY. THESE MODELS ARE PREFERRED AT THIS TIME  
WITH THE OTHER MODELS AT LOWER WEIGHTS.  
 
A HEAVY RAIN EVENT ACROSS THE MIDDLE OF THE COUNTRY IS STILL  
EXPECTED THROUGH WEDNESDAY NIGHT AS THE TROUGH TAPS GULF MOISTURE  
AND PLENTY OF ENERGY FROM THE ABOVE NORMAL TEMPERATURES THAT HAVE  
BEEN PERVASIVE UNDER THE RIDGE CENTERED OVER THE EASTERN CONUS.  
 
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML  
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
JACKSON  
 
 
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