098
FXUS10 KWNH 250426
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1225 AM EDT MON MAY 25 2020
VALID MAY 25/0000 UTC THRU MAY 28/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
WEAKENING SHORTWAVE CROSSING NORTHERN NEW ENGLAND ON MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A MID-LEVEL TROUGH CURRENTLY WEAKENING OVER THE GREAT LAKES REGION
WILL DAMPEN FURTHER ON MONDAY WHILE SHEARING ACROSS NORTHERN NEW
ENGLAND. THE MODELS ARE IN GOOD AGREEMENT WITH THE DETAILS OF
THIS, SO A GENERAL MODEL BLEND WILL BE PREFERRED.
SHORTWAVE OVER THE NORTHERN PLAINS THROUGH MONDAY
RELOADING NORTHERN STREAM TROUGH OVER NORTHERN PLAINS BY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A CLOSED LOW INITIALLY OVER WYOMING AND EASTERN MONTANA IS
FORECAST TO EVOLVE INTO AN OPEN WAVE AS IT REACHES THE WESTERN
DAKOTAS BY MONDAY AFTERNOON. BY TUESDAY THIS DISTURBANCE SHOULD
BECOME ABSORBED BY THE WESTERLIES ACROSS SOUTHERN CANADA. THE
GUIDANCE IS IN GOOD AGREEMENT WITH THE DETAILS OF THIS EXITING
SYSTEM. HOWEVER, BY LATER TUESDAY AND INTO WEDNESDAY, THE MODELS
SUPPORT AMPLIFICATION OF A NEW NORTHERN STREAM TROUGH OVER
SOUTHERN CANADA AND THE NORTHERN PLAINS. THIS WILL DRIVE SURFACE
LOW PRESSURE ACROSS SOUTHERN CANADA WITH A TRAILING COLD FRONT
THAT WILL BE CROSSING THE NORTHERN PLAINS. THE MODELS OVERALL ARE
FAIRLY WELL CLUSTERED WITH THE HEIGHT FALL EVOLUTION OF THIS NEXT
TROUGH, ALTHOUGH THE 12Z UKMET BECOMES A BIT OF A PROGRESSIVE
OUTLIER BY LATE WEDNESDAY, AND THE 12Z CMC IS PERHAPS JUST A TAD
TOO SLOW. THE 00Z NAM/GFS AND 12Z ECMWF ARE WELL CLUSTERED IN
BETWEEN TOWARD THE END OF THE PERIOD, AND BASED ON THIS, A BLEND
OF THESE SOLUTIONS WILL BE PREFERRED.
SYNOPTIC SCALE TROUGH OVER THE WEST EVOLVING INTO CLOSED LOW OVER
SOUTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A SYNOPTIC SCALE UPPER TROUGH INITIALLY OVER THE INTERMOUNTAIN
WEST WILL DROP EAST-SOUTHEAST OVER THE CENTRAL AND SOUTHERN PLAINS
OVER THE NEXT COUPLE OF DAYS, WITH A CUT-OFF UPPER LOW EXPECTED TO
SET UP OVER FAR NORTHERN TX BY LATE TUESDAY. THIS UPPER LOW SHOULD
THEN DRIFT VERY SLOWLY EASTWARD THROUGH NORTHEAST TEXAS BY EARLY
THURSDAY. MODEL MASS FIELD SPREAD IS MINIMAL THROUGH EARLY
TUESDAY, BUT BY LATE TUESDAY THROUGH THE END OF THE PERIOD, THE
12Z UKMET ENDS UP ON THE SOUTH SIDE OF THE GUIDANCE WITH THE
POSITION OF THE UPPER LOW. TOWARD THE END OF THE PERIOD, THE 12Z
CMC ALSO LOOKS LIKE IT MAY BE A TAD TOO SLOW, AS THE 18Z GEFS MEAN
AND 12Z ECENS MEAN SUPPORT THE 00Z NAM/GFS AND 12Z ECMWF WITH AN
UPPER LOW THAT IS OVER NORTHEAST TX. AT THE SURFACE, MULTIPLE
WAVES OF LOW PRESSURE WILL BE LIFTING NORTH ALONG A FRONT
ADVANCING EAST ACROSS THE PLAINS. GENERALLY THE BETTER MODEL
CLUSTERING AND ENSEMBLE SUPPORT RESIDES WITH THE 00Z GFS AND 12Z
ECMWF. SO, BASED ON THE LATEST TRENDS AND CLUSTERING OF SOLUTIONS,
A BLEND OF THE 00Z GFS AND 12Z ECMWF WILL BE PREFERRED FOR THE
MASS FIELD EVOLUTION OF THE UPPER TROUGH AND SURFACE WAVES.
MID-LEVEL TROUGH AND WEAK SURFACE LOW IMPACTING FLORIDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/GFS AND 12Z ECMWF
CONFIDENCE: MODERATE
AN UPPER LEVEL RIDGE WILL BE BUILDING ACROSS THE SOUTHEAST U.S.
EARLY THIS WEEK AND GRADUALLY OUT ACROSS THE WESTERN ATLANTIC BY
MIDWEEK. SOUTH OF THE UPPER RIDGE WILL BE A LOW TO MID-LEVEL
TROUGH AXIS WHICH IS EXPECTED TO LIFT NORTHWARD THROUGH THE
EASTERN GULF OF MEXICO AND THE FL PENINSULA GOING THROUGH TUESDAY.
BY WEDNESDAY, THIS ENERGY WILL BE ADVANCING NORTH INTO THE
SOUTHEAST U.S. WITHIN DEEP LAYER SOUTHERLY FLOW SITUATED BETWEEN
THE DEEP UPPER LOW OVER NORTHEAST TX AND THE BUILDING RIDGE OVER
THE WESTERN ATLANTIC. MULTIPLE WAVES OF LOW PRESSURE, POSSIBLY
CONVECTIVELY INDUCED, ARE EXPECTED TO EVOLVE WITH THIS SYSTEM WITH
ONE LOW LIFTING NORTH ACROSS THE EASTERN GULF OF MEXICO, AND
ANOTHER FORMING NEAR THE EAST COAST OF FL. GENERALLY THE GUIDANCE
IS MORE SUBTLE WITH THE WAVE OVER THE EASTERN GULF OF MEXICO
VERSUS THE WAVE ALONG THE FL EAST COAST, AS THE 00Z NAM/GFS AND
12Z ECMWF ALL HAVE RATHER WELL-DEFINED LOWS IN THE VICINITY OF
MELBOURNE, FL BY 12Z TUESDAY. THE 12Z CMC IS MORE ILL-DEFINED WITH
IT, BUT THE 12Z UKMET EVENTUALLY FORMS A RATHER WELL-DEFINED LOW
BY LATE TUESDAY IN THE SAME AREA. THE MAIN TAKEAWAY WITH THE 12Z
UKMET IS THAT IT IS AGAIN SLOW TO LIFT THE LOW TO MID-LEVEL TROUGH
NORTHWARD AND THUS IS SLOWER WITH ITS SURFACE WAVES. BY THE END OF
THE PERIOD, ALL OF THE MODELS SHOW A SURFACE WAVE ATTEMPTING TO
LIFT THROUGH THE SOUTHEAST U.S. AS THE SUPPORTING MID-LEVEL TROUGH
LIFTS NORTH. THE 12Z CMC AND 12Z UKMET ARE THE MOST DIVERGENT
SOLUTIONS RELATIVE TO THE MODEL CONSENSUS, WITH THE BETTER MODEL
CLUSTERING AND ENSEMBLE SUPPORT FAVORING A BLEND OF THE 00Z
NAM/GFS AND 12Z ECMWF, AND THUS THIS WILL BE THE PREFERENCE AT
THIS TIME.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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