148  
FXUS10 KWNH 241701  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
100 PM EDT TUE MAR 24 2020  
 
VALID MAR 24/1200 UTC THRU MAR 28/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
SHORTWAVE TRACKING FROM THE CENTRAL PLAINS TO THE EAST COAST ON  
WEDNESDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-GFS/GEFS BLEND  
CONFIDENCE: NEAR AVERAGE  
 
THE SOUTHERN STREAM TROUGH EXITING THE ROCKIES AND EMERGING OVER  
THE CENTRAL PLAINS IS FORECAST TO REMAIN INTACT AS IT REACHES THE  
EASTERN U.S ON WEDNESDAY. SURFACE CYCLOGENESIS IS IN PROGRESS  
ACROSS NORTHERN TEXAS AND OKLAHOMA, AND THIS LOW REACHES THE  
CENTRAL APPALACHIANS AND WEAKENS BY EARLY WEDNESDAY, WITH  
SECONDARY CYCLOGENESIS IS LIKELY OFF THE MID-ATLANTIC COAST BY  
WEDNESDAY AFTERNOON. THE 12Z NCEP RUNS MAINTAINED DECENT RUN TO  
RUN CONTINUITY...SO THE 24/12Z GFS AND THE 24/06Z GEFS MEAN WERE  
DECIDEDLY FAST OUTLIERS. AS A RESULT, STILL PREFERRED A  
NON-GFS/NON-GEFS MEAN MODEL COMPROMISE.  
 
LONGWAVE TROUGH OVER THE WESTERN U.S.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-UKMET BLEND AFTER 12Z THURSDAY  
CONFIDENCE: AVERAGE  
 
THE AMPLIFIED PATTERN OVER THE EASTERN PACIFIC WILL END UP  
PRODUCING A POSITIVELY TILTED LONGWAVE TROUGH AXIS WHICH WILL  
SLOWLY PROGRESS DOWN THE WEST COAST, GRADUALLY MOVE INLAND ACROSS  
THE DESERT SOUTHWEST BY FRIDAY MORNING AND BE ABOUT READY TO CROSS  
THE SOUTHERN ROCKIES BY FRIDAY EVENING. THE 12Z NCEP GUIDANCE  
LARGELY MAINTAINED CONTINUITY WITH RESPECT TO THE TIMING AND  
STRENGTH OF THE FEATURE...LEAVING THE UKMET A MORE AMPLIFIED  
OUTLIER THAN OTHER GUIDANCE BEGINNING ON THURSDAY. THE 24/12Z GFS  
WAS SLOWER THAN THE 24/00Z ECMWF, WITH THE SURFACE FEATURES  
REFLECTING THE PROCESSES ALOFT, BUT NOT ENOUGH OF A DIFFERENCE TO  
BE UNUSUABLE.  
 
STORM SYSTEM CROSSING NORTHERN TIER OF THE U.S. MIDWEEK  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM CONSENSUS  
CONFIDENCE: AVERAGE  
 
THE 24/12Z RUN OF THE NAM GOT INTO MUCH BETTER AGREEMENT WITH  
OTHER MODELS IN HANDLING THIS SYSTEM. THE RESULTING AGREEMENT  
AMONG THE VARIOUS GLOBAL MODELS WAS GOOD...SO A GENERAL COMPROMISE  
SHOULD WORK FINE. THE GFS HEIGHTS AT 700 MB MAY BE A BIT LOWER  
THAN OTHER GUIDANCE BY WEDNESDAY AFTERNOON OVER THE UPPER MIDWEST.  
OTHERWISE, DETAILS FROM ANY OF THE DETERMINISTIC MODELS COULD BE  
USED TO REFLECT SMALLER SCALE DETAILS.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
BANN  
 

 
 
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