662
FXUS10 KWNH 080632
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
131 AM EST SUN DEC 08 2019
VALID DEC 08/0000 UTC THRU DEC 11/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...LARGE SCALE TROF THAT DOMINATES THE BULK OF THE CONUS THROUGH
WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/ECENS MEAN BLEND WITH SOME LOWER WEIGHTED
00Z GEFS/GFS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
07Z UPDATE: THE OVERALL AGREEMENT IN THE NORTHERN STREAM MASS
FIELDS CONTINUE, BUT THE ARCTIC SHORTWAVE STILL REMAINS MUCH MORE
UNCERTAIN, WITH THE CMC STILL MUCH MORE AMPLIFIED/COMPACT THAT
OTHER SOLUTIONS. IN THE SOUTHERN STREAM, THE ECMWF REMAINED QUITE
SIMILAR BUT THE 00Z GEFS MEAN CONTINUES TO HEDGE MORE TOWARD THE
ECMWF/ECENS MEAN SOLUTION THAN THE 00Z GFS SPECIFICALLY. SO, WILL
CONTINUE WITH INITIAL PREFERENCE OF ECMWF/ECENS MEAN WITH SOME 0Z
GEFS/GFS IN THE BLEND PARTICULARLY IN THE SOUTHERN STREAM PORTION
OF THE LARGER GLOBAL TROF.
---PRIOR DISCUSSION---
A LARGE SCALE GLOBAL TROF IS DEVELOPING CURRENTLY WITH A DEEP
CLOSED VORTEX OVER NORTHERN HUDSON BAY, A NORTHERN STREAM
SHORTWAVE SLIDING DOWN THE CANADIAN ROCKIES THAT WILL SHARPEN AND
ACCELERATE ACROSS THE PLAINS MONDAY DRAWING A SOUTHERN HIGH PLAINS
LEE SURFACE CYCLONE UP THE SURFACE TROF INTO THE GREAT LAKES, AS
IT DEEPENS INTO A STRONG CYCLONE ACROSS QUEBEC BY EARLY TUES; WITH
AN ATTENDANT COLD FRONT THAT EXTENDS BACK TOWARD THE LOWER MS
VALLEY TUES. THE SOUTHERN PORTION OF THE FRONTAL ZONE IS
EXPECTED TO SLOW, AS THE CLOSED LOW CURRENTLY OFF THE WEST COAST
SLIDES INTO THE SOUTHWEST.
FOR THE MOST PART, THE GUIDANCE HAS COME INTO SOLID AGREEMENT IN
THE EVOLUTION/PLACEMENT OF THESE FEATURES WITH EXCEPTION TO THE
STRENGTH/SHAPE OF THE REMAINING PORTION OF THE SOUTHERN SHORTWAVE
AS IT CROSSES THE SOUTHERN PLAINS LATE TUES INTO WED. THE 18Z
GFS HAD BEEN VERY COMPACT AND ABNORMAL WITHIN THE SUITE, HOWEVER,
THE 00Z RUN, WHILE STILL STRONG/COMPACT, IS MUCH BETTER AND CLOSER
TO THE REMAINING GUIDANCE...PARTICULARLY THE MOST CONSISTENT
ECMWF/ECENS MEAN. THE 12Z UKMET IS EXTREMELY WEAK/SHEARED AND
THEREFORE ACCELERATES THROUGH THE SOUTHEAST, THIS PLACES THE UKMET
OUT OF BALANCE FEEDING INTO THE NORTHERN STREAM AS WELL...MAKING
IT LESS PREFERABLE IN THE NORTHEAST AS WELL BY 00Z WED. THE 18Z
GEFS IS MORE IN LINE WITH THE ECENS MEAN AND 12Z ECMWF...SO WOULD
PROVIDE STRONGER CONFIDENCE TOWARD THE ECMWF SOLUTION ACROSS THE
SOUTHERN STREAM. BUT OVERALL, A GFS/ECMWF BLEND IS SUPPORTED
OVERALL.
BEHIND THE MAIN HEIGHT-FALLS, A STRONG COMPACT COLD POCKET
ORIGINATING FROM N NUNAVUT IS EXPECTED TO DESCEND IN THE OPEN
NORTHERLY FLOW. IT IS THE CMC IS THAT IS VERY COLD AND VERY
STRONG WITH THE ASSOCIATED SHORTWAVE IN THIS ARCTIC STREAM THAT
DROPS INTO MN/DAKOTAS BY 00Z WED...AND IS CLEARLY OUT OF PLACE IN
THE ENSEMBLE SUITE. THE UKMET IS A BIT STRONGER/FASTER LIKE THE
CMC, THOUGH MORE TEMPERED...BUT STILL LESS FAVORED...SO MUCH LIKE
THE PRIOR LONG WAVE TROF, AN ECMWF/GFS BLEND IS PREFERRED THOUGH
SOME INCORPORATION OF THE 00Z NAM IS ACCEPTABLE FOR HIGHER
RESOLUTION DESIRES, PARTICULARLY FOR DEVELOPING LAKE EFFECT.
...APPROACHING ELONGATED/STRETCHED SHORTWAVE ENTERING PACIFIC NW
LATE TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~
PREFERENCE: 00Z GFS/GEFS BLEND
CONFIDENCE: AVERAGE
07Z UPDATE: LITTLE CHANGE WAS NOTED IN THE NEWER 00Z GUIDANCE,
WITH THE ECMWF STILL FASTER THAN THE INITIAL PREFERENCE. THE 00Z
UKMET/CMC WERE TRENDING A BIT MORE COMPACT LIKE THE ECMWF BUT
STILL REMAIN SLOWER AND MORE ON PAR WITH THE TIMING OF THE GFS,
YET STILL NOT IDEALLY MATCHED THE GFS/GEFS. SO WILL CONTINUE A
PREFERENCE OF THE GFS/GEFS AT AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
IN THE WEST...A PROGRESSIVE RIDGE BUILDS IN MONDAY TO WED AHEAD OF
THE NEXT SYSTEM. A LARGE GLOBAL SCALE CLOSED LOW SHEDS OFF ITS
SOUTHERN PERIPHERY SHORTWAVE ENERGY THAT SQUEEZES INTO THE RIDGE
ALLOWING FOR NORTH-SOUTH ELONGATION, IMPACTING THE CANADIAN AND
PACIFIC NORTHWEST COAST TO ABOUT CAPE MENDOCINO BY 11.00Z. THERE
THE ECMWF IS UNCHARACTERISTICALLY, FAST AND COMPACT MOVING THROUGH
THE RIDGE...AND WHILE SUPPORTED BY A BULK OF ECENS MEMBERS, IT
DOES NOT APPEAR CORRECT GIVEN THE STRETCHING ENVIRONMENT ENHANCED
BY THE ORIENTATION OF THE HIGHER TERRAIN...SO IS LESS FAVORED
OVERALL. THE 00Z NAM WHILE MOVING ABOUT THE SAME RATE AS THE
GFS/GEFS... IS VERY STRONG, WITH THE ENERGY AND THEREFORE VERY
SHARP IN THE MASS FIELDS. SO WOULD HEDGE TOWARD THE GFS/GEFS BY
THE END OF DAY 3, PARTICULARLY IN THE NORTHWEST AND INTO THE
NORTHERN US ROCKIES.
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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