919
FXUS10 KWNH 270447
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1246 AM EDT SAT JUN 27 2020
VALID JUN 27/0000 UTC THRU JUN 30/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER QUEBEC
TROUGH IMPACTING THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z 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 MODELS SUPPORT THE CLOSED LOW ACTUALLY THEN DROPPING SOUTH
INTO THE INTERIOR OF THE NORTHEAST GOING THROUGH MONDAY AND
TUESDAY. THE 00Z NAM IS STILL A LITTLE MORE ROBUST WITH THIS
SHORTWAVE AND RESULTS IN A SOMEWHAT STRONGER CLOSED LOW THAT IS ON
THE SOUTHWEST SIDE OF THE MODEL CONSENSUS ACROSS THE NORTHEAST BY
THE END OF THE PERIOD. ADDITIONALLY, THE 12Z CMC IS A LITTLE TO
THE SOUTHWEST OF THE MODEL CONSENSUS. THE BETTER MODEL CLUSTERING
AND STRONGER ENSEMBLE SUPPORT CURRENTLY RESIDES WITH THE 00Z GFS,
12Z UKMET AND 12Z ECMWF, AND SO A BLEND OF THESE SOLUTIONS WILL
AGAIN BE PREFERRED.
DEEP UPPER TROUGH/CLOSED LOW DIGGING INTO THE WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS/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 12Z CMC
TAKES THE UPPER LOW FARTHER SOUTH THAN THE OTHER GUIDANCE. THE 00Z
NAM GRADUALLY ENDS UP WITH A STRONGER UPPER LOW IMPACTING THE
NORTHERN ROCKIES FROM SUNDAY NIGHT THROUGH EARLY TUESDAY. WILL
PREFER A BLEND OF THE BETTER CLUSTERED 00Z GFS, 12Z UKMET AND 12Z
ECMWF SOLUTIONS WHICH ALSO AGAIN HAVE GOOD ENSEMBLE SUPPORT.
SHORTWAVES LIFTING NORTHEAST OVER THE PLAINS/MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 18Z GEFS MEAN AND 12Z ECENS MEAN
CONFIDENCE: AVERAGE
AHEAD OF THE DEEP WESTERN U.S. TROUGH/CLOSED LOW WILL BE A PAIR OF
SHORTWAVE TROUGHS THAT EJECT NORTHEAST OUT OF THE SOUTHWEST AND
ACROSS THE PLAINS AND MIDWEST. THE 00Z NAM IS A STRONG OUTLIER
WITH THE FIRST SHORTWAVE AS IT RIDES NORTHEAST FROM THE CENTRAL
PLAINS TO THE UPPER MIDWEST GOING THROUGH SUNDAY WITH THE GLOBAL
MODELS LARGELY FLATTER ALTHOUGH THE 12Z CMC WAS FAIRLY AMPLIFIED
AS WELL. THE SECOND SHORTWAVE HAS SOME MODEL SPREAD NOTED AS THE
12Z ECMWF AND 12Z ECENS MEAN SUPPORT A SOMEWHAT STRONGER SOLUTION
VERSUS THE REMAINING GUIDANCE WHICH IS FLATTER. FOR NOW, A BLEND
OF THE ENSEMBLE MEANS WILL BE PREFERRED WITH BOTH SHORTWAVE
IMPULSES.
REMNANT ENERGY ACROSS THE LOWER MS VALLEY
WEAKNESS LINGERING OVER TEXAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: 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 AGAIN BE
PREFERRED WITH THE WEAK TROUGH OVER TEXAS.
UPPER TROUGH/LOW OVER MANITOBA/SASKATCHEWAN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z UKMET/12Z ECMWF
CONFIDENCE: AVERAGE
A SEPARATE CLOSED LOW AND ASSOCIATED TROUGH OVER SOUTHWEST CANADA
WILL DRIVE DEEPENING SURFACE LOW PRESSURE OVER AREAS OF MANITOBA
AND SASKATCHEWAN GOING THROUGH SATURDAY AND SUNDAY. THE 12Z CMC IS
THE STRONGEST SOLUTION WITH THE ENERGY, WITH THE 00Z NAM AND 00Z
GFS SOLUTIONS BOTH NOW GENERALLY THE WEAKEST. THE 12Z UKMET AND
12Z ECMWF SOLUTIONS ARE IN BETWEEN THE TWO CAMPS, AND A BLEND OF
THESE SOLUTIONS WILL BE PREFERRED FOR THE TIME BEING.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page