252
FXUS10 KWNH 091834
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
134 PM EST MON DEC 09 2019
VALID DEC 09/1200 UTC THRU DEC 13/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EASTERN CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/12Z GFS/12Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODEL GUIDANCE IS IN GOOD AGREEMENT WITH RESPECT TO THE TIMING
OF THE NORTHERN STREAM SHORTWAVE AND ASSOCIATED SFC COLD FRONT AS
IT CROSSES THE NORTHEAST AND MID ATLANTIC TONIGHT-TUE AND STALLS
OVER FL WED.
THE SECONDARY 700 MB WAVE IS ALSO IN GOOD AGREEMENT AS IT MOVES
ACROSS THE UPPER LAKES ON DAY 2 AND INTO THE NORTHEAST DAY 3. THE
12Z GFS, 00Z ECMWF, AND 12Z NAM ARE IN GOOD AGREEMENT ON THE
TIMING AND LOCATIONS OF THE FRONT, ALTHOUGH THE 12Z NAM HAS A
PREFERRED INTERMEDIATE POSITION WITH THE LOW IN QUEBEC 00Z THU.
..WESTERN TO CENTRAL CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 06Z GEFS/09Z SREF WITH 12Z GFS
CONFIDENCE: AVERAGE
IN THE WEST, THE 12Z NAM BECOMES AN OUTLIER AS MOST GUIDANCE MOVES
THE 700 MB TROUGH ONSHORE TUE AND STEADILY ACROSS THE INTER
MOUNTAIN WEST WED AND ON TO THE PLAINS THU. THE 12Z NAM BECOMES
THE SLOWEST SOLUTION WITH LOWER HEIGHTS AND A HIGHER AMPLITUDE
TROUGH.
PREFERENCE WILL BE GIVEN TO THE 12Z GFS AND 09Z SREF MEAN, 06Z
GEFS MEAN. THE 12Z UKMET AND 12Z ECMWF HAS SLOWED DOWN THE
FORWARD PROGRESSION OF THE TROUGH TO NARROW THE DIFFERENCES.
IN THE SOUTHERN STREAM TROUGH, DIFFERENCES DEVELOP ON DAY 3
REGARDING THE AMPLITUDE AND TIMING, WITH THE 00Z ECMWF AND
CANADIAN MORE AMPLIFIED AND SLOWER THAN THE NAM/GFS AND RESPECTIVE
09Z SREF/06Z GEFS ENSEMBLE MEANS. WITH MORE ECMWF ENSEMBLE MEMBERS
NOT DEVELOPING A CLOSED 500 MB LOW LIKE THE OPERATIONAL RUN, AN
INTERMEDIATE, MORE PROGRESSIVE SOLUTION LIKE THE 12Z NAM AND 06Z
GEFS/09Z SREF MEAN CLUSTER IS PREFERRED. THE 12Z ECMWF MOVED THE
700 MB TROUGH FASTER INTO THE SOUTHERN PLAINS ON THU MORNING, IN
CLOSER AGREEMENT WITH THE MAJORITY CLUSTER.
THE 12Z UKMET REMAINS FAST IN THE PROGRESSION OF THE SOUTHERN
STREAM TROUGH ACROSS THE SOUTHWEST AND SOUTHERN PLAINS.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
PETERSEN
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