096  
FXUS10 KWNH 101837  
PMDHMD  
 
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
236 PM EDT FRI APR 10 2020  
 
VALID APR 10/1200 UTC THRU APR 14/0000 UTC  
 
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
 
12Z MODEL EVALUATION...WITH PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
   
..DEEP CYCLONE EXITING THE NORTHEAST
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE ANOMALOUSLY DEEP CLOSED LOW IMPACTING THE NORTHEAST TODAY WILL  
BE EJECTING NORTHEAST ACROSS SOUTHEAST CANADA TONIGHT AND  
SATURDAY. THE GUIDANCE SHOWS VERY GOOD LARGE SCALE AGREEMENT WITH  
THE MASS-FIELD EVOLUTION, SO A GENERAL MODEL BLEND WILL BE  
PREFERRED AS THIS SYSTEM BEGINS TO EXIT.  
 
   
..CLOSED LOW EXITING THE SOUTHWEST
 
   
..ENERGY EJECTING TOWARD THE LOWER MS VALLEY BY SUNDAY
 
   
..POWERFUL SURFACE LOW OVER THE GREAT LAKES BY MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: 12Z GFS/12Z UKMET/00Z ECMWF AND ECENS/GEFS BLEND  
CONFIDENCE: AVERAGE...THROUGH 60 HOURS  
BECOMING BELOW AVERAGE...AFTER 60 HOURS  
 
THE LARGE, SLOW-MOVING CUT-OFF SOUTHERN STREAM LOW OVER SOUTHERN  
CALIFORNIA WILL GRADUALLY MOVE TOWARD SOUTHERN AZ/NM ON SATURDAY  
AND THEN OPEN UP INTO A PROGRESSIVE SHORTWAVE ACROSS THE SOUTHERN  
PLAINS BY EARLY SUNDAY. BY LATE SUNDAY, THIS ENERGY WILL BEGIN TO  
TAKE ON A NEGATIVE TILT OVER THE LOWER MS VALLEY AND QUICKLY REACH  
THE OH VALLEY BY EARLY MONDAY. THE ENERGY COUPLED WITH INCREASING  
INFLUENCE FROM A STRONG NORTHERN STREAM TROUGH AMPLIFYING OVER THE  
UPPER MIDWEST SUNDAY AND MONDAY WILL LEAD THE WAY FOR A POWERFUL  
SURFACE CYCLONE TO LIFT OVER LOWER MI ON MONDAY. THE GUIDANCE HAS  
GENERALLY COME INTO BETTER AGREEMENT WITH THE EVOLUTION OF THE  
SHORTWAVE ENERGY ACROSS THE SOUTH, WITH MULTI-CYCLE TRENDS OF THE  
GFS COMING IN SLOWER AND TOWARD THE NON-NCEP MODEL CAMP. TODAY'S  
DIFFERENCES ARE MUCH MORE FOCUSED ON THE OH VALLEY AND GREAT LAKES  
REGION.  
 
THE 12Z NAM ENDS UP WITH A SOMEWHAT FASTER SHORTWAVE PROGRESSION  
UP NORTH ACROSS THE OH VALLEY INTO LOWER MI, AND A LOW TRACK ON  
THE LEFT SIDE OF THE DETERMINISTIC MODEL SPREAD. THE 12Z CMC  
OVERALL IS AN OUTLIER IN BEING THE WEAKEST SOLUTION BUT ALSO  
REFLECTS A TRACK FARTHER NORTHWEST ACROSS THE WESTERN GREAT LAKES.  
THE 12Z ECMWF THOUGH WHICH HAD BEEN FARTHER SOUTHEAST HAS MADE A  
SIZABLE JUMP WITH ITS TRACK TO THE NORTHWEST AND TOWARD THE  
NAM/CMC CAMP. HOWEVER, THE 00Z ECENS/12Z CMCE SUITES AND  
ESPECIALLY THE 00Z/06Z/12Z GEFS SUITES FAVOR A SOLUTION THAT IS  
QUITE DEEP, BUT WITH A LOW TRACK STILL SOUTHEAST OF THE 12Z  
NAM/CMC/ECMWF SOLUTIONS. HAVING SAID THAT, THERE IS A CAMP OF EC  
ENSEMBLE MEMBERS THAT DO TAKE THE LOW OFF FARTHER TO THE  
NORTHWEST, AND THE KEY FOR THIS TO VERIFY WILL BE THE INTRUSION OF  
STRONGER NORTHERN STREAM ENERGY FROM THE UPPER MIDWEST AND  
SUBSEQUENT PHASING. THE NEW ECMWF REFLECTS THIS POSSIBILITY.  
CONFIDENCE IS SOMEWHAT LIMITED LATE IN THE PERIOD AS THERE IS ROOM  
FOR A SOMEWHAT DEEPER LOW TO TRACK FARTHER WEST OVER THE GREAT  
LAKES, BUT BASED ON THE LATEST CLUSTERING FROM THE 12Z GFS, 12Z  
UKMET, AND FORMER 00Z ECMWF SOLUTIONS, A BLEND OF THESE SOLUTIONS  
WILL BE PREFERRED, AND IN CONJUNCTION WITH THE ENSEMBLE MEANS.  
 
   
..AMPLIFYING UPPER TROUGH OVER THE NORTHERN U.S. BY MONDAY
 
 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: ABOVE AVERAGE  
 
THE MODELS BRING AMPLIFYING SHORTWAVE/JET ENERGY SOUTHEASTWARD  
FROM THE SOUTHERN COAST OF AK AND THE ADJACENT YUKON TERRITORY  
DOWN ACROSS SOUTHWEST CANADA AND OUT ACROSS THE NORTHERN ROCKIES  
AND NORTHERN PLAINS BY SUNDAY. BY MONDAY, THIS ENERGY WILL AMPLIFY  
INTO A DEEP LONGWAVE TROUGH OVER THE NORTHERN U.S. THAT WILL  
GRADUALLY PHASE WITH THE AFOREMENTIONED SOUTHERN STREAM ENERGY  
EJECTING ACROSS THE SOUTH AND LIFTING TOWARD THE GREAT LAKES  
REGION. THE MODELS ARE IN GOOD AGREEMENT WITH THE DETAILS OF THE  
LONGWAVE TROUGH EVOLUTION. SO, A GENERAL MODEL BLEND WILL BE  
PREFERRED WITH THIS.  
 
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
 
ORRISON  
 

 
 
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