167  
FXUS10 KWNH 280653  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
252 AM EDT THU MAY 28 2020  
 
VALID MAY 28/0000 UTC THRU MAY 31/1200 UTC  
 
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
00Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
 
AMPLIFYING NORTHERN STREAM TROUGH ACROSS THE GREAT LAKES AND  
NORTHEAST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 00Z ECMWF/UKMET/GFS BLEND  
CONFIDENCE: MODERATE-HIGH  
 
A NORTHERN STREAM TROUGH INITIALLY OVER SOUTH-CENTRAL CANADA IS  
FORECAST TO AMPLIFY OVER THE FEW COUPLE OF DAYS, AND WILL HERALD A  
PATTERN CHANGE FOR MUCH OF THE CENTRAL AND EASTERN U.S. BY THE END  
OF THE WEEK AS A RELATIVELY STRONG COLD FRONT TRACKS SOUTHWARD  
FROM CANADA, BRINGING A HIGH QUALITY AIRMASS FOR MUCH OF THE  
NORTH-CENTRAL U.S. TO CLOSE OUT THE WEEK. THIS BUILDING TROUGH  
WILL BE AMPLIFIED ENOUGH TO EXERT ITS INFLUENCE ON THE SOUTHERN  
U.S. CLOSED LOW, WHICH WILL THEN EVOLVE INTO A PHASED SYNOPTIC  
SCALE TROUGH FROM THE DEEP SOUTH TO THE GREAT LAKES BY FRIDAY  
AFTERNOON AND INTO THE WEEKEND. THE MAIN MODEL DIFFERENCE  
CONTINUES TO BE WITH THE 00Z CMC THAT IS CONSIDERABLY MORE  
AMPLIFIED, AND THIS IS SIMILAR TO ITS RECENT 12Z RUN. THE NAM IS  
ALSO STRONGER, BUT NOT TO THE DEGREE OF THE CMC. THERE IS ENOUGH  
AGREEMENT AMONG THE ECMWF/UKMET/GFS TO MERIT A BLEND OF THOSE  
THREE MODELS.  
 
 
CLOSED LOW OVER ARKANSAS THAT BECOMES ABSORBED BY NORTHERN STREAM  
FLOW  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: MODERATE-HIGH  
 
THE BROAD UPPER LOW INITIALLY OVER ARKANSAS SLOWLY LIFTS  
NORTHEASTWARD TO SOUTHERN ILLINOIS BY THURSDAY EVENING, BEFORE  
BECOMING ABSORBED AND MERGED WITH THE BUILDING TROUGH FROM THE  
GREAT LAKES REGION. A GENERAL MODEL BLEND WORKS HERE BEFORE THE  
SYSTEM MERGES.  
 
TROPICAL DEPRESSION BERTHA  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: DETERMINISTIC CONSENSUS WITH GREATER WEIGHTING TO 00Z  
NAM IS CLOSE TO 3Z WPC ADVISORY  
CONFIDENCE: REFER TO WPC ADVISORY  
 
BERTHA MADE LANDFALL ALONG THE CENTRAL COAST OF SOUTH CAROLINA  
WEDNESDAY AND IS CURRENTLY TRACKING INLAND ACROSS THE  
APPALACHIANS. AS THE SYSTEM WEAKENS, IT IS FORECAST BY WPC TO  
MOVE NORTHWARD ACROSS WEST VIRGINIA AND THEN WESTERN PENNSYLVANIA  
BEFORE DISSIPATING. CURRENTLY, A NAM/GFS BLEND IS CLOSE TO THE 3Z  
WPC ADVISORY FOR BERTHA BEFORE THE SYSTEM WEAKENS AND MERGES WITH  
AN ADVANCING MID-LEVEL TROUGH OVER THE GREAT LAKES REGION LATE  
THURSDAY.  
 
SUBTROPICAL CLOSED LOW REACHING CENTRAL CALIFORNIA BY SATURDAY  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH SATURDAY MORNING, THEN 00Z  
ECMWF/UKMET BLEND  
CONFIDENCE: MODERATE-HIGH  
 
THE MODELS SHOW GOOD AGREEMENT ON THE TRACK OF A CLOSED LOW  
APPROACHING CENTRAL/NORTHERN CALIFORNIA BY SATURDAY, BUT DIFFER  
WITH TIMING BY SATURDAY MORNING AND BEYOND. THE 12Z CMC BECOMES  
SLOWER WITH BRINGING THE SYSTEM INLAND AND SOUTH OF THE ENSEMBLE  
MEANS. BY SATURDAY NIGHT, THE GFS BECOMES FASTER IN BRINGING THE  
SHORTWAVE NORTHWARD ON THE WEST SIDE OF THE BUILDING WESTERN HIGH  
PLAINS RIDGE, AND THE NAM INDICATES THE STRONGEST SOLUTION AS THE  
FEATURE LIFTS NORTHWARD ACROSS THE PACIFIC NORTHWEST. A GENERAL  
MODEL BLEND WORKS WELL THROUGH SATURDAY MORNING, AFTER WHICH A 00Z  
ECMWF/UKMET BLEND WOULD WORK.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
HAMRICK  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page