209   
FXUS10 KWNH 101640  
PMDHMD  
  
MODEL DIAGNOSTIC DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1239 PM EDT SUN MAY 10 2020  
  
VALID MAY 10/1200 UTC THRU MAY 14/0000 UTC  
  
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR  
INGEST...  
  
12Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
...SURFACE LOW MOVING FROM GREAT LAKES TO NEW ENGLAND THROUGH  
TUESDAY...  
...ENERGY AMPLIFYING FROM THE OH VALLEY TO THE NORTHEAST MON AND  
TUES...  
...SHORTWAVE MOVING ACROSS THE GREAT LAKES AND NORTHEAST TUESDAY  
AND WEDNESDAY...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 12.12Z; FOLLOWED BY A  
ECMWF/ECENS BLEND  
CONFIDENCE: AVERAGE  
  
LARGE CYCLONIC FLOW WILL PERSIST OVER THE GREAT LAKES AND EASTERN  
US THROUGH EARLY NEXT WEEK WITH LARGE HEIGHT ANOMALIES CENTERED  
OVER THE HUDSON BAY REGION. A PAIR OF COMPACT SHORTWAVES WILL WORK  
THROUGH BASE OF THE LARGE SCALE CLOSED LOW, THE FIRST OF WHICH  
MOVES FROM THE UPPER MISSISSIPPI RIVER VALLEY TODAY TOWARD THE  
NORTHEAST EARLY NEXT WEEK. A DEEPENING SURFACE LOW WILL TRACK FROM  
NEAR CHICAGO TO THE GULF OF MAINE. THROUGH ABOUT 36 HOURS, THE LOW  
TRACK AND DEPTH IS WELL AGREED UPON BY THE LATEST GUIDANCE BUT  
THEN DIVERGES AS THE SYSTEM EXITS THE COAST OFF MAINE. THE GFS HAS  
A NORTHERN TRACK AND THE NAM ALSO IS ON THE NORTHERN SIDE OF THE  
SPREAD. THE NON-NCEP GUIDANCE SHOWS FAIRLY GOOD CLUSTERING ON THE  
SOUTHERN SIDE OF THE SPREAD. LOOKING AT THE ENSEMBLES, THE  
ECMWF/ECENS ARE NEARLY IDENTICAL WHILE THE GEFS MEAN LEANS TOWARD  
THE ECMWF/ECENS SOLUTION, PUTTING THE DETERMINISTIC GFS AS THE  
OUTLIER. FOR THIS REASON, A NON-GFS SOLUTION IS RECOMMENDED AFTER  
12.12Z.  
  
A SECONDARY, COMPACT SHORTWAVE IS THEN FORECAST TO WRAP BEHIND THE  
INITIAL SYSTEM OVER THE NORTHERN/INTERIOR NEW ENGLAND STATES  
TUESDAY/TUESDAY NIGHT. HERE, MODEL AGREEMENT IS RELATIVELY STABLE,  
THOUGH THE CMC AND UKMET SEEM TO HAVE SOME TIMING/DEPTH ISSUES.  
THE UKMET IS ON THE FASTER SIDE OF THE MODEL GUIDANCE WHILE THE  
CMC IS A BIT TOO DEEP AS THE SHORTWAVE PIVOTS OVER NEW ENGLAND.  
FOR THESE REASONS, A GENERAL MODEL BLEND SHOULD BE SUFFICIENT  
THROUGH ABOUT 12.12Z BUT BEYOND THAT, GIVEN THE ISSUES WITH THE  
INITIAL AND SECONDARY SHORTWAVES/LOWS, A BLEND UTILIZING PRIMARILY  
THE ECMWF/ECENS MEAN IS PREFERRED.  
   
..SHORTWAVE ENERGY CROSSING THE SOUTHWEST ON SUNDAY  
   
..ENERGY SHEARING ACROSS THE SOUTHERN PLAINS BY TUE  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND  
CONFIDENCE: AVERAGE  
  
A SUBTLE SHORTWAVE WILL MOVE THROUGH PORTIONS OF THE DESERT  
SOUTHWEST TODAY BEFORE CROSSING INTO THE SOUTHERN PLAINS AND LOWER  
MISSISSIPPI VALLEY EARLY NEXT WEEK. IN THE LARGE SCALE SENSE,  
THERE ARE VERY LITTLE DIFFERENCES SEEN IN THE LATEST MODEL  
GUIDANCE AND A GENERAL MODEL BLEND SHOULD MORE THAN SUFFICE FOR  
MASS FIELD PURPOSES. AS THE SYSTEM EJECTS INTO THE PLAINS, THERE  
ARE SOME MAGNITUDE DIFFERENCES IN QPF BUT THESE SHOULD BE RESOLVED  
ON A SMALLER SCALE THAN THE SYNOPTIC PATTERN.  
  
...UPPER TROUGH/CLOSED LOW LIFTING ALONG THE NORTHWEST COAST  
MON-WED...  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
PREFERENCE: GENERAL MODEL BLEND THROUGH 12.12Z; NON-NAM THEREAFTER  
CONFIDENCE: AVERAGE  
  
A LONGWAVE TROUGH AND CLOSED LOW APPROACHES THE PACIFIC NORTHWEST  
EARLY NEXT WEEK. AS THE SYSTEM APPROACHES THE COAST, IT WILL  
SLOW/STALL THANKS TO STUBBORN RIDGING INLAND. THE CLOSED LOW WILL  
THEN WOBBLE/MEANDER THROUGH THE END OF THE PERIOD. PIECES OF THE  
ENERGY WILL SEPARATE AND MOVE INLAND, INTERACTING WITH ANOTHER  
PIECE OF SHORTWAVE ENERGY OVER THE SOUTHERN CANADIAN ROCKIES.  
THROUGH ABOUT 48 HOURS, A GENERAL MODEL BLEND SHOULD BE SUFFICIENT  
AS THERE IS LITTLE SPREAD SEEN IN THE LATEST GUIDANCE. BEYOND THAT  
TIME FRAME, THE NAM BECOMES LESS USABLE AS IT APPEARS TO BE TOO  
QUICK TO ABSORB MORE OF THE ENERGY INTO THE ROCKIES SYSTEM. THE  
MORE RELIABLE ECMWF/GFS/UKMET IN THE 48-84 HOUR RANGE SHOW THE  
CLOSED LOW LINGERING LONGER, WHICH FITS THE PATTERN AND  
TELECONNECTIONS.  
  
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML  
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML  
  
TAYLOR  
  
  
 
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