436
FXUS10 KWNH 160651
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
150 AM EST MON DEC 16 2019
VALID DEC 16/0000 UTC THRU DEC 19/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...MID-LEVEL TROUGH TRACKING FROM THE CENTRAL HIGH PLAINS TO THE
EASTERN U.S. THROUGH WEDNESDAY MORNING...
...SURFACE LOW ORGANIZING EAST OF THE MISSISSIPPI RIVER INTO
TUESDAY MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
..07Z UPDATE
THE 00Z ECMWF/UKMET/CMC TRENDED TOWARD ONE ANOTHER WHILE WHILE THE
SURFACE LOW OFFSHORE OF NEW ENGLAND CONTINUES TO SHOW SOME
DIFFERENCES, A BLEND OF THE 00Z NAM/GFS/ECMWF/UKMET/CMC WILL
PROVIDE A REASONABLE COMPROMISE.
..PREVIOUS DISCUSSION FOLLOWS
MINOR TIMING DIFFERENCES REMAIN WITH THE 500 MB TROUGH AXIS MOVING
EASTWARD ALONG WITH LATITUDE DIFFERENCES WITH THE RELATED SURFACE
WARM FRONT EXTENDING TO THE EAST COAST. THE 12Z ECMWF/UKMET ARE
SLOWER WHILE THE 00Z NAM/GFS ARE FASTER. THE 12Z CMC IS ALSO
FASTER BUT DISPLACED SLIGHTLY FARTHER SOUTH WITH THE MAIN AXIS OF
VORTICITY WITHIN THE MID-LEVEL TROUGH AXIS. AT THIS POINT, A BLEND
OF THE 00Z NAM, 00Z GFS AND 12Z ECMWF MATCH NEAREST TO THE MIDDLE
OF THE LATEST MODEL SPREAD, BUT WITH SLIGHTLY LESS WEIGHT ON THE
12Z ECMWF. AS THE SURFACE LOW TRACKS OFFSHORE, THE 00Z GFS APPEARS
TOO FAR NORTH BUT THE 12Z ECMWF TOO FAR SOUTH. MODERATE SPREAD
REMAINS IN THE ENSEMBLE SCATTER LOW PLOTS WHICH IS PREVENTING
HIGHER CONFIDENCE WITH THIS SYSTEM.
...MID-LEVEL SHORTWAVE CLIPPING THE GREAT LAKES TUESDAY NIGHT AND
REACHING NEW ENGLAND LATE WEDNESDAY...--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
..07Z UPDATE
THE 00Z UKMET ADJUSTED TO THE REMAINING MODEL CONSENSUS AND LITTLE
IN THE WAY OF DIFFERENCES REMAIN. THEREFORE, A GENERAL MODEL BLEND
IS PREFERRED.
..PREVIOUS DISCUSSION FOLLOWS
A DEEP BUT COMPACT CLOSED LOW SWINGS THROUGH THE NORTHERN GREAT
LAKES REGION TUESDAY. MODEL AGREEMENT IS FAIRLY GOOD, BUT THE 12Z
UKMET STANDS OUT AS A SLOW DETERMINISTIC OUTLIER. BETTER SUPPORT
EXISTS FOR A NON 12Z UKMET BLEND AT THIS TIME.
..TROUGH APPROACHING THE WESTERN U.S. TUESDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
..07Z UPDATE
THE 00Z UKMET AND 00Z ECMWF SPED UP WHILE THE 00Z CMC SLOWED DOWN
WITH THE 500 MB TROUGH THAT REACHES THE WEST COAST. THE 00Z
ECMWF/UKMET CONSENSUS IS JUST A BIT FASTER THAN PREFERRED GIVEN
THE LATEST ENSEMBLE SPREAD. A BLEND OF THE 12Z/15 ECMWF AND 00Z/16
ECMWF APPEARS BEST FOR THE WESTERN U.S. AT THIS TIME.
..PREVIOUS DISCUSSION FOLLOWS
THE LATEST MODELS AGREE WITH A CLOSED LOW WITHIN THE BASE OF A
TROUGH AXIS NEARING THE WEST COAST TUESDAY NIGHT. TIMING
DIFFERENCES SHOW UP ON TUESDAY WITH THE 00Z NAM SLOWER AND 12Z
UKMET, 00Z GFS AND 12Z CMC FASTER. THROUGH THURSDAY MORNING, THE
12Z CMC IS FASTEST WITH THE 00Z GFS NEXT FASTEST. THE 00Z NAM
SPEEDS UP TOWARD THE MIDDLE WHILE THE 12Z UKMET SLOWS DOWN TOWARD
THE MIDDLE BY WEDNESDAY EVENING. ALL IN ALL, A MIDDLE OF THE ROAD
TO SLIGHTLY SLOWER APPROACH IS FAVORED GIVEN LARGE ENSEMBLE SPREAD
AND A TREND TO BE SLOWER. THIS PLACEMENT IS CLOSE TO A 12Z
ECMWF/UKMET BLEND FROM MONDAY THROUGH THURSDAY MORNING ACROSS THE
WEST.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
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