067
FXUS10 KWNH 261943
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
342 PM EDT FRI JUN 26 2020
VALID JUN 26/1200 UTC THRU JUN 30/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
19Z UPDATE: THE 12Z UKMET TRENDED SLIGHTLY TO THE WEST WITH THE
CLOSED LOW OVER NEW ENGLAND COMPARED TO ITS 00Z RUN, AND THIS ALSO
HOLDS TRUE FOR THE 12Z CMC. THE 12Z ECMWF TRENDED SLIGHTLY TO THE
EAST WITH THE AXIS OF THE UPPER LEVEL TROUGH OVER THE
INTERMOUNTAIN WEST, BUT NOT ENOUGH TO APPEAR SIGNIFICANT.
OTHERWISE NO MAJOR CHANGES IN THE MODEL PREFERENCES.
CLOSED LOW OVER QUEBEC
TROUGH IMPACTING THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/12Z UKMET/12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS ARE IN GOOD AGREEMENT ON THE DETAILS OF THE LARGE
CLOSED LOW OVER QUEBEC AND SOUTHWARD EXTENSION OF THE TROUGH
ACROSS THE NORTHEAST U.S. GOING THROUGH SATURDAY. BY SUNDAY, THE
MODELS SUGGEST A NEW SHORTWAVE TROUGH WILL CROSS THE GREAT LAKES
AND HELP TO AMPLIFY THE SYNOPTIC SCALE TROUGH OVER THE NORTHEAST,
AND THE CORE OF THE UPPER LOW NUDGES A LITTLE TO THE SOUTH ACROSS
NORTHERN NEW ENGLAND. THE 12Z NAM IS STILL A LITTLE MORE ROBUST
WITH THIS SHORTWAVE AND RESULTS IN A SOMEWHAT STRONGER CLOSED LOW
THAT IS SLIGHTLY TO THE EAST OF THE MODEL CONSENSUS ACROSS THE
NORTHEAST BY THE END OF THE PERIOD. ADDITIONALLY, THE 00Z CMC IS
A LITTLE TO THE SOUTHWEST OF THE MODEL CONSENSUS BY DAY 3, SO
THEREFORE A GFS/ECMWF/UKMET CAN BE RECOMMENDED.
DEEP UPPER TROUGH/CLOSED LOW DIGGING INTO THE WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/12Z UKMET/12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A DEEP UPPER TROUGH AND ASSOCIATED CLOSED LOW IS FORECAST TO
AMPLIFY ACROSS THE NORTHERN ROCKIES AND INTERMOUNTAIN WEST THIS
WEEKEND AS AN UPPER LEVEL RIDGE BUILDS ACROSS THE GULF OF ALASKA
AND ALSO ACROSS THE MIDWEST AND GREAT LAKES REGION, SUGGESTING A
POTENTIAL OMEGA BLOCK PATTERN. THE MODELS ARE IN GOOD AGREEMENT
ON THE EVOLUTION THROUGH SUNDAY EVENING, AFTER WHICH THE CMC TAKES
THE UPPER LOW FARTHER SOUTH THAN THE OTHER GUIDANCE, AND THE GFS
APPEARS TOO FAST TO LIFT THE LOW OUT TO THE NORTHEAST BY MONDAY
AFTERNOON. THEREFORE, A NAM/UKMET/ECMWF BLEND SHOULD WORK WELL
FOR THIS REGION.
SHORTWAVES LIFTING NORTHEAST OVER THE PLAINS/MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/12Z GEFS MEAN/00Z ECENS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE
AHEAD OF THE DEEP WESTERN U.S. TROUGH/CLOSED LOW WILL BE A PARADE
OF SHORTWAVE TROUGHS THAT EJECT NORTHEAST OUT OF THE SOUTHWEST AND
ACROSS THE PLAINS AND MIDWEST. BOTH THE NAM AND TO A GREATER
DEGREE THE GFS APPEAR MORE AMPLIFIED WITH THE FIRST SHORTWAVE,
WHEREAS THE NON-NCEP GUIDANCE SUGGESTS A FLATTER SOLUTION. THE
SECOND SHORTWAVE HAS A GREATER DEGREE OF MODEL SPREAD, AND THE
ECMWF/ECENS ARE STRONGER THAN THE GFS/GEFS, WITH THE UKMET
SUPPORTING A DECENT MIDDLE GROUND SOLUTION. THEREFORE SOME
WEIGHTING OF THE ENSEMBLE MEANS WOULD BE PRUDENT FOR THE SECOND
FEATURE CROSSING THE CENTRAL PLAINS.
REMNANT ENERGY ACROSS THE LOWER MS VALLEY
WEAKNESS LINGERING OVER TEXAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODEL SUPPORT A GRADUAL BUILDING OF THE SUBTROPICAL RIDGE THIS
WEEKEND ACROSS THE FL PENINSULA AND ADJACENT AREAS OF THE GULF
COAST STATES. SOME OF THE WEAK SHORTWAVE ENERGY LINGERING OVER
THE LOWER MISSISSIPPI VALLEY SHOULD SHEAR OUT OVER TOP OF THE
RIDGE THROUGH SATURDAY. HOWEVER, THERE WILL STILL BE A BROAD
MID-LEVEL WEAKNESS/TROUGH LINGERING OVER TEXAS WHICH SHOULD TEND
TO RETROGRADE WESTWARD THROUGH SATURDAY, BEFORE THEN LIFTING NORTH
ACROSS THE SOUTHERN AND CENTRAL PLAINS AHEAD OF THE DEEP WESTERN
U.S. TROUGH/CLOSED LOW. A GENERAL MODEL BLEND WILL BE PREFERRED
WITH THE WEAK TROUGH OVER TEXAS AND GULF COAST.
UPPER TROUGH/LOW OVER MANITOBA/SASKATCHEWAN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/12Z ECMWF BLEND
CONFIDENCE: AVERAGE
A SURFACE LOW CURRENTLY OVER CENTRAL ONTARIO IN COMBINATION WITH A
MID-LEVEL SHORTWAVE TROUGH OVER THE NORTHERN GREAT LAKES WILL
CONTINUE TO TRACK EAST AND BRING A COLD FRONT ACROSS THE GREAT
LAKES REGION AND THEN THE INTERIOR NORTHEAST. THE 12Z NAM IS
STRONGER WITH THIS SYSTEM AND HAS A SECONDARY SURFACE LOW CROSSING
NEW YORK ON SATURDAY, AND THE GFS IS SLIGHTLY MORE PROGRESSIVE.
THE UKMET AND ECMWF ARE CLOSE TO THE MODEL CONSENSUS, SO A BLEND
OF THESE SOLUTIONS WILL BE PREFERRED 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
HAMRICK
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