721
FXUS10 KWNH 031843
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
143 PM EST TUE MAR 03 2020
VALID MAR 03/1200 UTC THRU MAR 07/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW WEAKENING EASTWARD FROM THE SOUTHERN PLAINS TO THE
EAST COAST THROUGH FRIDAY...
...SURFACE LOW TRACKING FROM THE CENTRAL GULF COAST TO THE EAST
COAST AND THEN NORTHWARD THROUGH THE WESTERN ATLANTIC...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
MODEL DIFFERENCES SHOW UP EARLY WITH THIS SYSTEM OVER TEXAS BY
WEDNESDAY EVENING WITH A STRONGER 700-500 MB LOW DEPICTED IN THE
12Z NAM COMPARED TO THE REMAINING GUIDANCE. THE STRONGER NAM ALSO
HAS A SURFACE LOW THAT IS FARTHER NORTH IN TIME ALONG THE GULF
COAST. THE MODELS ARE IN GOOD AGREEMENT THAT THE MID-LEVEL
SHORTWAVE WEAKENS INTO CONFLUENT FLOW BUT THE 00Z ECMWF STOOD OUT
WITH A FASTER TIMING WHICH TRANSLATED INTO A SURFACE LOW THAT
BECOMES FARTHER OFFSHORE OF THE EAST COAST BY THURSDAY EVENING.
THE 12Z ECMWF TRENDED SLIGHTLY SLOWER WITH THE SHORTWAVE WHILE THE
12Z UKMET TRENDED FASTER.
THE 00Z/03 (LATEST) ENSEMBLE SCATTER LOW PLOTS SHOWED A NOTABLE
JUMP TO THE EAST WITH THE SURFACE LOW VALID FRIDAY MORNING OFF OF
THE MID-ATLANTIC COAST COMPARED TO THE 12Z/02 CYCLE AND PREVIOUS
CYCLES. FOR THURSDAY NIGHT, THE LATEST ENSEMBLE DISTRIBUTION SHOWS
THE CANADIAN MEMBERS FARTHEST WEST, WITH THE GEFS TOWARD THE
MIDDLE AND THE ECMWF MEMBERS FARTHER OFFSHORE. GIVEN THE LATEST
DETERMINISTIC SPREAD AND CONSIDERING ENSEMBLE DISTRIBUTION OVER
THE PAST 4 CYCLES, A PLACEMENT NEAR THE 12Z GFS, 12Z ECMWF AND 12Z
UKMET IS PREFERRED.
...MID-LEVEL TROUGH/CLOSED LOW NEARING THE GREAT LAKES THURSDAY
INTO FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
THE ENSEMBLES HAVE SHOWN BETTER CONVERGENCE OF MEMBERS REGARDING
THE DEPTH AND TIMING OF THE TROUGH AXIS AS IT TRACKS EAST. THE 00Z
UKMET/CMC WERE NOTED TO BE ON THE SLOWER SIDE OF THE ENSEMBLE
MEMBERS WHICH IF ANYTHING, HAVE TRENDED SLIGHTLY QUICKER OVER
THEIR PAST 4 12/00Z CYCLES. THE 12Z UKMET TRENDED FASTER, AND IS
NOW IN GOOD AGREEMENT WITH THE CONSISTENT ECMWF (12Z AND 00Z
ECMWF). HOWEVER, THE 12Z CMC REMAINS SLOWER WITH THE TROUGH
PROGRESSION TOWARD THE EAST. MEANWHILE, THE 12Z GFS WAS NOTED TO
BE A BIT FASTER THAN THE REMAINING MODEL CONSENSUS AND ON THE
NORTH SIDE WITH THE SURFACE TO 850 MB LOW. THE 12Z NAM, 12Z ECMWF
AND 12Z UKMET SHOWED BETTER AGREEMENT WITH THIS SYSTEM AND ARE
CONSIDERED BEST WITH THINKING THE GFS/GEFS ARE TOO FAR NORTH WITH
THE LOW LEVEL LOW.
..REMAINDER OF SYSTEMS IMPACTING THE LOWER 48
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
ACROSS THE REST OF THE LOWER 48, A DEEPENING SURFACE LOW WILL
TRACK ACROSS THE NORTHEAST FOLLOWED BY LOW AMPLITUDE SHORTWAVE
WHICH WILL TRACK FROM THE CENTRAL AND NORTHERN GREAT PLAINS TO TO
THE NORTHERN MID-ATLANTIC COAST BY WEDNESDAY EVENING. ALSO, A
LARGER AMPLITUDE MID-UPPER LEVEL TROUGH IS EXPECTED TO NEAR THE
WEST COAST ON FRIDAY. THE MODELS ARE IN FAIR AGREEMENT WITH THESE
SYSTEMS AND SO A GENERAL MODEL BLEND IS PREFERRED FOR THE
REMAINDER OF THE CONUS.
NO CHANGES ARE RECOMMENDED ACROSS THE REMAINDER OF THE CONUS BASED
ON THE 12Z ECMWF/UKMET/CMC.
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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