721   
FXUS10 KWNH 290445  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1244 AM EDT MON JUN 29 2020  
  
VALID JUN 29/0000 UTC THRU JUL 02/1200 UTC  
  
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
CLOSED LOW ANCHORED OVER NEW ENGLAND  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON-NAM BLEND  
CONFIDENCE: ABOVE AVERAGE  
  
AN UPPER-LEVEL LOW INITIALLY OVER SOUTHERN QUEBEC IS FORECAST TO  
REACH CENTRAL NEW ENGLAND BY MONDAY AND THEN BECOME ANCHORED IN  
PLACE THROUGH THE MIDDLE OF THE WEEK AS IT BECOMES CUT OFF FROM  
THE MAIN NORTHERN STREAM FLOW. THE 00Z NAM TENDS TO DROP MORE  
ENERGY FARTHER SOUTH COMPARED TO THE GLOBAL MODELS WHICH OVERALL  
ARE FAIRLY WELL CLUSTERED THROUGH THE PERIOD. WILL PREFER A  
NON-NAM BLEND AS A RESULT.  
  
DEEP UPPER TROUGH/CLOSED LOW ACROSS THE INTERMOUNTAIN WEST  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF  
CONFIDENCE: SLIGHTLY ABOVE AVERAGE  
  
A STRONG MID-UPPER LEVEL LOW CURRENTLY OVER THE PACIFIC NORTHWEST  
IS FORECAST TO CONTINUE AMPLIFYING ACROSS THE NORTHERN ROCKIES AND  
INTERMOUNTAIN WEST THROUGH TUESDAY MORNING AS AN UPPER-LEVEL RIDGE  
BUILDS ACROSS THE MIDWEST AND GREAT LAKES REGION. THEREAFTER, THE  
CORE OF THE UPPER LOW SHOULD BE REFOCUS FARTHER NORTH OVER  
SOUTHWEST CANADA GOING THROUGH WEDNESDAY AND THURSDAY. THIS WILL  
YIELD A QUASI OMEGA-BLOCK PATTERN ACROSS THE NORTH-CENTRAL U.S.  
THROUGH THE MIDDLE OF THE WEEK. THE 00Z NAM IS OVERALL A BIT  
STRONGER THAN THE GLOBAL MODELS WHICH IT HAS BEEN TENDING TO  
ADVERTISE OVER THE LAST COUPLE OF DAYS. THE 12Z CMC THOUGH IS  
AGAIN SLOWER TO LIFT THE ENERGY NORTH OUT OF THE INTERMOUNTAIN  
WEST, AND AS IT EVENTUALLY DOES SO, IT ENDS UP SHIFTING STRONGER  
HEIGHT FALLS FARTHER EAST WITH GREATER IMPACTS ACROSS THE NORTHERN  
HIGH PLAINS COMPARED TO THE OTHER MODELS. WILL AGAIN PREFER THE  
BETTER AGREEMENT/CLUSTERING OF THE 00Z GFS, 12Z UKMET AND 12Z  
ECMWF SOLUTIONS WITH THIS SYSTEM.  
  
MCV/WEAK MID-LEVEL LOW OVER MN  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: BLEND OF THE 00Z GFS/12Z UKMET/12Z ECMWF  
CONFIDENCE: AVERAGE  
  
A STRONG MCV AND ASSOCIATED WEAK MID-LEVEL LOW CENTER CURRENTLY  
OVER MN IS EXPECTED TO LIFT NORTH THROUGH WESTERN ONTARIO OVER THE  
NEXT COUPLE OF DAYS. OVERALL, THE 12Z CMC APPEARS TO BE TOO SLOW  
WITH THE FORWARD MOTION, AND EVEN THE 00Z NAM LAGS THE MODEL  
CONSENSUS A TAD BY LATER MONDAY AND TUESDAY. A SOMEWHAT MORE  
PROGRESSIVE SOLUTION IS EXPECTED BASED ON THE MODEL TRENDS OVER  
THE LAST 12 TO 24 HOURS AND THE LATEST SATELLITE IMAGERY. A BLEND  
OF THE 00Z GFS, 12Z UKMET AND 12Z ECMWF WILL BE PREFERRED FOR THE  
TIME BEING.  
  
SHORTWAVE AMPLIFYING TOWARD MID MS VALLEY BY MONDAY NIGHT  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: NON_ECMWF BLEND...THROUGH 60 HOURS  
            NON-NAM BLEND...AFTER 60 HOURS  
CONFIDENCE: SLIGHTLY BELOW AVERAGE  
  
THE GUIDANCE SUPPORTS A CONVECTIVELY ENHANCED SHORTWAVE OR MCV  
LIFTING NORTHEAST ACROSS EASTERN TX AND TOWARD THE MID MS VALLEY  
BY MONDAY NIGHT. OVERALL, THE 12Z ECMWF APPEARS TO BE A BIT TOO  
WEAK WITH THE EVOLUTION OF THIS SYSTEM, BUT ALL OF THE MODELS DO  
SUPPORT THE ENERGY CROSSING UP THROUGH MO AND IA GOING THROUGH  
TUESDAY. HOWEVER, THERE IS SIGNIFICANT MODEL SPREAD THEREAFTER AS  
THE MODELS DISAGREE ON WHETHER THE ENERGY GETS PULLED NORTH  
THROUGH THE UPPER MIDWEST AHEAD OF THE DEEP UPSTREAM TROUGH OVER  
THE WEST, OR IF THE SYSTEM GETS LEFT BEHIND IN THE MIDDLE OF THE  
MEAN LAYER RIDGE OVER THE MIDWEST. THE 00Z GFS AND 12Z UKMET  
SUPPORT THE ENERGY LIFTING NORTH THROUGH THE UPPER MIDWEST, BUT  
THE 00Z SUGGEST THE ENERGY GETS LEFT BEHIND OVER IA AND THEN  
BEGINS TO ACTUALLY SETTLE BACK DOWN TO THE SOUTH WHILE WEAKENING.  
THE 12Z CMC AND 12Z ECMWF BOTH SUGGEST THE ENERGY WILL TEND TO  
SPLIT APART WITH SOME OF THE ENERGY BREAKING AWAY TO THE NORTH AND  
SOME OF IT DROPPING DOWN TO THE SOUTH. A NON-ECMWF BLEND WILL BE  
PREFERRED THROUGH ABOUT 60 HOURS, WITH A NON-NAM BLEND AFTER 60  
HOURS. CONFIDENCE WITH THIS EVOLUTION THOUGH IS CERTAINLY A BIT  
LIMITED.  
  
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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