126
FXUS10 KWNH 220656
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 AM EDT WED APR 22 2020
VALID APR 22/0000 UTC THRU APR 25/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP TROUGH/CLOSED LOW INITIALLY OVER THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ARE IN VERY GOOD AGREEMENT WITH THE DETAILS OF THE DEEP
TROUGH AND CLOSED LOW IMPACTING THE NORTHEAST THROUGH WEDNESDAY.
THE SYSTEM SHOULD EXIT UP ACROSS SOUTHEAST CANADA BY THURSDAY. A
GENERAL MODEL BLEND WILL BE PREFERRED.
...SOUTHERN STREAM TROUGH CROSSING THE SOUTHERN PLAINS/LOWER MS
VALLEY THROUGH EARLY THURSDAY...
...ASSOCIATED ENERGY AND SURFACE LOW CROSSING THE OH VALLEY AND
MID-ATLANTIC BY FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z UKMET/ECMWF AND 00Z GEFS/12Z ECENS MEAN BLEND
CONFIDENCE: AVERAGE
THE MODELS TAKE THE SOUTHERN STREAM MID-LEVEL TROUGH OVER THE
SOUTHWEST OFF TO THE EAST OVER THE NEXT COUPLE OF DAYS, WITH THE
ENERGY CROSSING THE SOUTHERN PLAINS ON WEDNESDAY AND REACHING THE
LOWER MS VALLEY BY EARLY THURSDAY. THIS ENERGY ALONG WITH A
DEEPENING SURFACE LOW CENTER WILL THEN ADVANCE NORTHEAST AND CROSS
THE OH VALLEY AND MID-ATLANTIC REGION BY FRIDAY AS AN ATTENDANT
COLD FRONT SWEEPS ACROSS THE SOUTH. THE SYSTEM WILL EXIT OFFSHORE
BY FRIDAY NIGHT. THE 00Z NAM IS THE FASTEST SOLUTION WITH THE
TROUGH AND SURFACE LOW. CONSIDERING THE AMPLITUDE OF THE EJECTING
SHORTWAVE, THE NAM APPEARS TOO WEAK WITH ITS SURFACE REFLECTION.
THE 00Z GFS FOR ITS PART MAY PERHAPS BE EPISODICALLY BE A TAD TOO
FAST, BUT THE BIGGER CONCERN MAY TEND TO BE WITH THE OVERALL
LATITUDE OF ITS SURFACE LOW TRACK INVOLVING THE OH
VALLEY/MID-ATLANTIC, WHICH IS A LITTLE NORTH OF THE GENERALLY WELL
CLUSTERED 00Z NON-NCEP SOLUTIONS. HOWEVER, IT SHOULD BE NOTED
THOUGH THAT THE 00Z CMC AGAIN APPEARS TO BE A TAD TOO WEAK WITH
ITS SURFACE LOW. REGARDING TIMING AND DEPTH OF THE SYSTEM, THE 00Z
UKMET AND 00Z ECMWF TEND TO HAVE BETTER ENSEMBLE SUPPORT (I.E. 00Z
GEFS/12Z ECENS MEANS). SO, WILL FAVOR A BLEND OF THE UKMET/ECMWF
SOLUTIONS AND ALONG WITH THE ENSEMBLE MEANS FOR THE TIME BEING.
..INITIAL SHORTWAVE/LOW CENTER ACROSS THE NORTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS BRING A NORTHERN STREAM SHORTWAVE AND ASSOCIATED LOW
CENTER DOWN FROM CANADA AND ACROSS THE NORTHERN PLAINS ON
WEDNESDAY WHICH IS EXPECTED TO DAMPEN OUT OVER THE MIDWEST
WEDNESDAY NIGHT AS THE STRONGER SOUTHERN STREAM SYSTEM EVOLVES
ACROSS THE SOUTHERN PLAINS AND LOWER MS VALLEY. A GENERAL MODEL
BLEND WILL BE PREFERRED WITH THIS SYSTEM GIVEN VERY MODEST MODEL
MASS FIELD SPREAD.
..SECOND SHORTWAVE/LOW CENTER ACROSS THE NORTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z CMC AND 00Z ECMWF
CONFIDENCE: AVERAGE
THE MODELS BRING A SECOND NORTHERN STREAM SHORTWAVE AND ASSOCIATED
LOW CENTER DOWN FROM CANADA AND ACROSS THE NORTHERN PLAINS ON
THURSDAY AND THEN ATTEMPT TO AMPLIFY IT A BIT OVER THE MIDWEST ON
FRIDAY. THE 00Z GFS AND 00Z UKMET END UP BEING THE STRONGEST
SOLUTIONS WITH THIS ENERGY, AND WHILE MOST OF THE MODELS GENERALLY
DAMPEN OUT THE LOW CENTER, THE UKMET ACTUALLY HOLDS ON TO A RATHER
WELL-DEFINED LOW CENTER OVER THE MIDWEST GOING INTO SATURDAY. THE
00Z NAM, 00Z CMC AND 00Z ECMWF ARE ALL WEAKER WITH THE NAM OVERALL
THE WEAKEST. THE 00Z GEFS MEAN AND 12Z ECENS MEAN GENERALLY FAVOR
THE CMC/ECMWF CAMP, AND SO A BLEND OF THESE SOLUTIONS WILL BE
PREFERRED, BUT IT SHOULD BE NOTED THAT THERE ARE SOME GEFS MEMBERS
THAT DO FAVOR THE STRONGER GFS, SO A STRONGER EVOLUTION OF THIS
ENERGY CANNOT BE RULED OUT.
..SHORTWAVE TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST
..ENERGY AMPLIFYING INTO THE LOWER MS VALLEY BY SATURDAY
..ASSOCIATED DEEPENING SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z CMC/ECMWF AND 12Z ECENS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE MODELS BRING YET ANOTHER SHORTWAVE DOWN ACROSS THE
INTERMOUNTAIN WEST WHICH IS THEN FORECAST TO AMPLIFY ACROSS THE
SOUTHERN PLAINS ON FRIDAY AND CROSS THE LOWER MS VALLEY BY EARLY
SATURDAY. THE MODELS, ESPECIALLY THE NON-NCEP MODELS, SHOW THE
TROUGH BECOMING NEGATIVELY TILTED BY EARLY SATURDAY AND THIS WILL
DRIVE ANOTHER DEEPENING SURFACE LOW CENTER. THE 00Z NAM AND 00Z
UKMET BECOME WEAKER OUTLIER SOLUTIONS AT THE SURFACE AND ALOFT
WITH THE SYSTEM, WITH THE MAIN DIFFERENCE BEING THAT THE NAM IS A
BIT FASTER, AND ALSO THE UKMET IS SUGGESTING TWO LOW CENTERS WITH
OVER THE LOWER MS VALLEY AND ONE EVOLVING OVER THE MIDWEST BY THE
END OF THE PERIOD GIVEN PROXIMITY OF STRONGER NORTHERN STREAM
SHORTWAVE ENERGY LURKING OVER THE MIDWEST. THE 00Z GFS APPEARS TO
BE A BIT TOO PROGRESSIVE BY FRIDAY/SATURDAY AND PROBABLY TAKES ITS
ENERGY A BIT TOO FAR NORTH, BUT IT HAS AGREEMENT WITH THE UKMET IN
HAVING STRONGER NORTHERN STREAM ENERGY NEARBY. THE DIFFERENCE
BETWEEN THE UKMET AND GFS IS THAT THE GFS STILL HAS A MORE
DOMINANT SOUTHERN STREAM SHORTWAVE TROUGH AND THUS A DOMINANT
SOUTHERN STREAM SURFACE LOW.
THE GFS IS SUPPORTED BY THE 00Z CMC AND 00Z ECMWF SOLUTIONS WITH
THE IDEA OF THERE BEING ONE CONSOLIDATED LOW EVOLVING THROUGH THE
LOWER MS VALLEY BY THE END OF THE PERIOD AND A MORE DOMINANT
SOUTHERN STREAM TROUGH, BUT THAT IS WHERE THE AGREEMENT ENDS AS
THE CMC/ECMWF CAMP IS FARTHER SOUTH AND SLOWER WITH THE SURFACE
LOW EVOLUTION. THE CMC/ECMWF CAMP IS GENERALLY SUPPORTED BY THE
12Z ECENS MEAN, BUT THE 00Z GEFS MEAN TENDS TO FAVOR A COMPROMISE
BETWEEN THE GFS AND CMC/ECMWF CLUSTER. THE PREFERENCE FOR NOW WILL
BE TOWARD A BLEND OF THE SLOWER CMC/ECMWF AND ECENS MEAN. HOWEVER,
GIVEN SOME OF THE UNCERTAINTIES OVER HOW STRONG THE NEARBY
NORTHERN STREAM ENERGY AND RELATED INTERACTION WILL BE, CONFIDENCE
IS A BIT LIMITED IN THE FRIDAY/SATURDAY TIME FRAME.
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