172
FXUS10 KWNH 100443
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1142 PM EST MON DEC 09 2019
VALID DEC 10/0000 UTC THRU DEC 13/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EASTERN CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/NAM AND 12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODEL GUIDANCE MASS FIELDS CONTINUE TO TIGHTEN WITH THE
NORTHERN STREAM LARGE SCALE CYCLONE AND ASSOCIATED DEEP SURFACE
LOW IN THE GREAT LAKES CURRENTLY. THE ATTENDANT COLD FRONT IS
ALSO WELL TIMED AND PLACED THROUGH THE MID-WEEK INCLUDING THE VERY
STRONG JET. SMALLER SCALE, DRY SLOT/MOISTURE RIBBONS CONTINUE TO
COME INTO TIGHTER AGREEMENT AS WELL BUT THE 12Z UKMET HAS A WET
BIAS CURRENTLY WITH THIS SYSTEM AND IT LOOKS IT AGAIN ALONG THE
EAST COAST/PIEDMONT REGION THAT FEEDS A BIT UPSCALE TO THE JET
HOLDING THE TRAILING INFLECTION/RIGHT ENTRANCE A BIT TO MAKE IT A
BIT LESS FAVORABLE. OTHER-WISE THE 00Z GFS/NAM AND 12Z ECMWF
CONTINUE TO BE VERY TIGHT OVERALL.
ADDITIONALLY, THE ARCTIC SHORTWAVE/KICKER IS TIMED AND SHAPED WELL
TO HAVE INCREASED CONFIDENCE IN THE OVERALL EVOLUTION THROUGH TO
END OF WEEK IN THE EAST. CONFIDENCE IN A 00Z GFS/NAM AND 12Z
ECMWF BLEND IS SLIGHTLY ABOVE AVERAGE.
..WESTERN TO CENTRAL CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/18Z GEFS AND 12Z ECMWF/ECENS BLEND
CONFIDENCE: AVERAGE
IN THE WAKE OF THE LARGE VORTEX THAT HAS DOMINATED THE NORTHEAST
PORTION OF THE CONTINENT, ENHANCED RIDGING EXISTS ALONG THE WEST
COAST, WITH AN APPROACHING SOUTHEAST SHORTWAVE TROF EXTENSION OF A
LARGER ALASKAN CLOSED LOW INTO THE PACIFIC NORTHWEST TO N
CALIFORNIA BY LATE TUESDAY. THIS WAVE CONTINUES TO
STRETCH/ELONGATE THROUGH THE RIDGING HELPING TO SPLIT THE
SHORTWAVE ENERGY INTO A NORTHERN STREAM PACKET THROUGH THE
BORDERLAND ROCKIES AS WELL A SOUTHERN PORTION OF THE WAVE ENTERING
THE GREAT BASIN. THE GFS HAS BEEN TRENDING BEST WITH THE
EVOLUTION OF THIS SITUATION WITH A STRONGER REFLECTION IN THE
SOUTHERN STREAM WHILE THE NORTHERN WAVE KEEPS PACE WITH WEAK
PHASING. ONLY THE 12Z UKMET IS OUT OF TOLERANCE THROUGH THE
ROCKIES, STILL FAVORING A STRONGER NORTHERN STREAM WHICH LEADS TO
A FASTER EVOLUTION AND SURGE OF THE JET ACROSS THE CENTRAL MS
RIVER VALLEY TOWARD THE END OF THE FORECAST PERIOD... WHICH
DEFLATES THE SUBTROPICAL SHORTWAVE LIFTING NORTH AND SQUASHES THE
DEVELOPMENT OF GULF COAST SYSTEM AT THE END OF DAY 3. OBVIOUSLY,
THE UKMET IS NOT FAVORED IN THE EVOLUTION. WITH THE 12Z
ECMWF/ECENS TRENDING TOWARD THE GFS/GEFS EVOLUTION THERE WAS
GROWING CONFIDENCE. HOWEVER, THE 00Z GFS SHIFTED TOWARD A WEAKER
SOLUTION AND STARTING LOOKING MORE LIKE THE UKMET, BECOMING VERY
WEAK AND FAST BY THE END OF DAY 3. WHILE REDUCING CONFIDENCE,
HOPING THIS IS A ONE-OFF SOLUTION GIVEN ITS BREAK FROM GROWING
ENSEMBLE CONGRUENCE. SO WILL FAVOR A 00Z NAM/18Z GEFS AND 12Z
ECMWF/ECENS MEAN SOLUTION AT AVERAGE CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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