536
FXUS10 KWNH 201748
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1247 PM EST WED NOV 20 2019
VALID NOV 20/1200 UTC THRU NOV 24/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW CROSSING THE FOUR CORNERS INTO THE PLAINS
FRIDAY/SATURDAY...
...POTENTIAL NORTHERN STREAM SHORTWAVE CROSSING THE NORTH-CENTRAL
U.S. FRIDAY NIGHT...
...SURFACE LOW MOVING FROM THE LOWER MISSISSIPPI VALLEY INTO THE
CENTRAL APPALACHIANS FRIDAY NIGHT INTO SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/ECMWF MEAN BLEND
CONFIDENCE: BELOW AVERAGE
A COMPLEX INTERACTION OF FEATURES ALONG WITH ABOVE AVERAGE MODEL
SPREAD AND POOR RUN TO RUN CONSISTENCY RESULTS IN BELOW AVERAGE
CONFIDENCE REGARDING THE EVOLUTION OF A STORM SYSTEM MOVING FROM
THE SOUTHWEST TO THE TENNESSEE VALLEY. THE ENSEMBLES ARE IN BETTER
AGREEMENT WITH THE TRACK OF THE CLOSED LOW OVER SOUTHERN
CALIFORNIA THIS MORNING. HOWEVER, THE 12Z GFS APPEARS TO BE FASTER
WITH THE TRACK OF THIS FEATURE STARTING ON FRIDAY.
TO THE NORTH, THERE IS POTENTIAL INTERACTION WITH A SHORTWAVE
TROUGH WHICH ORIGINATES SOUTH OF ALASKA. AS THIS TROUGH MOVES EAST
AND ENCOUNTERS A STRONG MID-LEVEL RIDGE OVER BRITISH COLUMBIA. THE
12Z NAM, 00Z UKMET AND 00Z CMC ARE IN AGREEMENT THAT THE SHORTWAVE
IS SLIGHTLY SLOWER/STRONGER WITH THE BULK OF THE ENERGY MOVING
INTO WASHINGTON/IDAHO/MONTANA EARLY FRIDAY. MEANWHILE, THE 12Z GFS
AND 00Z ECMWF ARE IN AGREEMENT THAT THE SHORTWAVE IS A BIT FASTER
ALLOWING IT TO TRACK THROUGH/ATOP THE RIDGE AND INTO MINNESOTA BY
SATURDAY MORNING. ENSEMBLES SHOW THE 12Z GFS AS A STRONG OUTLIER,
HOWEVER, THE 12Z GFS INITIALIZATION (12Z/20) MATCHES SLIGHTLY
CLOSER TO OBSERVED WATER VAPOR IMAGERY REGARDING THE SHORTWAVE
COMPARED TO THE MORE WESTWARD 12Z NAM. FOR THIS REASON, FEEL THE
12Z GFS/00Z ECMWF IDEA IS MORE LIKELY TO VERIFY BUT TO A WEAKER
DEGREE THAN DEPICTED BY THE 12Z GFS AND EVEN THE 00Z ECMWF. THE
00Z ECMWF MEAN TEMPERS THE AMPLITUDE OF THE 00Z ECMWF ENOUGH TO BE
USED AS A FAVORABLE BLEND FOR THE PREFERENCE.
..REMAINDER OF THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-12Z NAM BLEND
CONFIDENCE: AVERAGE
THE MODELS SHOW GOOD AGREEMENT WITH THE REMAINDER OF THE SYSTEMS
IMPACTING THE LOWER 48, SPECIFICALLY WITH A DEEPENING MID-LEVEL
TROUGH/LOW FORECAST TO AFFECT THE UPPER MISSISSIPPI VALLEY AND NEW
ENGLAND ON THURSDAY AND FRIDAY AND A CLOSED LOW EXPECTED TO FORM
OFFSHORE OF THE WEST COAST AND DROP SOUTHWARD THIS WEEKEND. THE
ONLY EXCEPTION ACROSS THE LOWER 48 IS WITH A 500 MB SHORTWAVE TO
REACH THE CENTRAL PLAINS TONIGHT, WITH A RELATED SURFACE LOW
TRACKING INTO THE GREAT LAKES REGION ON THURSDAY. THE 12Z NAM WAS
NOTED TO BE FASTER WITH THE TRACK OF THIS LOW AS WELL AS TO BE
COLDER IN THE WAKE OF THE LOW/COLD FRONT.
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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