585
FXUS10 KWNH 030655
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT MON AUG 03 2020
VALID AUG 03/0000 UTC THRU AUG 06/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..SHORTWAVE/LOW CENTER EXITING THE LOWER GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE GUIDANCE IS IN VERY GOOD AGREEMENT ON THE DETAILS OF THE
EXITING SHORTWAVE/SURFACE LOW OVER THE LOWER GREAT LAKES REGION,
SO A GENERAL MODEL BLEND WILL BE PREFERRED WITH THIS SYSTEM.
..TROPICAL STORM ISAIAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 03Z NHC ADVISORY PACKAGE
BEST MODEL PROXY: 00Z ECMWF
THE 00Z GFS AND ESPECIALLY THE 00Z UKMET/ECMWF SOLUTIONS HAVE
TRENDED FASTER WITH THE NORTHWARD AND THEN NORTH-NORTHEASTWARD
ADVANCE OF TROPICAL STORM ISAIAS UP ACROSS THE CAROLINAS,
MID-ATLANTIC AND NORTHEAST OVER THE NEXT 48 TO 60 HOURS.
MEANWHILE, THE 00Z CMC TRENDED A TAD SLOWER FROM ITS PREVIOUS RUN,
WITH THE 00Z NAM ULTIMATELY QUITE SLOW AND DEFINITELY A SLOWER
OUTLIER. THE GFS AND UKMET OUTPACE THE 03Z NHC TRACK AFTER ABOUT
24 HOURS, WITH THE GFS A TAD LEFT OF THE NHC TRACK. HOWEVER, THE
00Z ECMWF AND TO AN EXTENT THE 00Z CMC ARE VERY CLOSE TO THE NHC
TRACK, WITH THE ECMWF JUST A TAD LEFT OF THE NHC FORECAST. ONE
CONCERN WITH THE CMC THOUGH IS ITS ERRONEOUSLY WEAKER SURFACE
REFLECTION OF THE STORM. REGARDING THE 00Z HREF SUITE OF GUIDANCE
THROUGH 48 HOURS, THE MEMBERS ARE LEFT OF THE NHC TRACK WITH
EXCEPTION OF THE 00Z ARW WHICH IS CLOSER AND IS JUST A TAD LEFT OF
THE NHC FORECAST. YESTERDAY'S 12Z ECENS MEAN IS THE ONLY SOLUTION
FAVORING THE SLOWEST GUIDANCE LIKE THE NAM, BUT THE 00Z GEFS MEAN
IS FASTER AND IS GENERALLY A BLEND OF THE GFS, UKMET AND ECMWF
SOLUTIONS WHICH MEANS IT IS JUST A LITTLE FASTER THAN THE NHC
FORECAST. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY PACKAGE
FOR MORE DETAILS.
..BROAD TROUGH FROM THE GREAT LAKES TO THE GULF COAST
..CLOSED LOW OVER ONTARIO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A BROAD TROUGH EXTENDING FROM THE GREAT LAKES DOWN TO THE CENTRAL
GULF COAST ON MONDAY WILL BE KEY IN ALLOWING TROPICAL STORM ISAIAS
TO LIFT NORTH AND THEN NORTH-NORTHEAST UP ALONG THE EASTERN
SEABOARD OVER THE NEXT 48 TO 60 HOURS. THE MODELS ARE IN GOOD
AGREEMENT IN MAINTAINING THE BROAD TROUGH THROUGH THE PERIOD, BUT
WITH SOME STRONGER NORTHERN STREAM ENERGY OVER THE GREAT LAKES
REGION FAVORING A CLOSED LOW EVOLUTION UP OVER ONTARIO. SUFFICIENT
AGREEMENT IS NOTED WITH THE GLOBAL MODELS SUCH THAT A GENERAL
MODEL BLEND CAN BE PREFERRED.
..UPPER TROUGH CROSSING THE PACIFIC NORTHWEST MONDAY
...ENERGY DROPPING DOWN OVER THE NORTHERN PLAINS/MIDWEST FOR
TUESDAY/WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/GFS/ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AN UPPER TROUGH WILL CROSS IN THROUGH THE PACIFIC NORTHWEST ON
MONDAY AND CROSS FAR SOUTHWEST CANADA BEFORE THEN DROPPING
SOUTHEAST AND DIGGING ACROSS THE NORTHERN PLAINS AND MIDWEST
TUESDAY AND WEDNESDAY. THE 00Z UKMET GRADUALLY BECOMES A WEAKER
AND SOMEWHAT MORE PROGRESSIVE OUTLIER WITH THE ENERGY. MEANWHILE,
THE 00Z CMC STILL EVENTUALLY ENDS UP A TAD SLOWER AND DEEPER WITH
THE ENERGY AS IT DIGS DOWN ACROSS THE MIDWEST BY THE END OF THE
PERIOD. THE 00Z NAM/GFS/ECMWF SOLUTIONS ARE GENERALLY
WELL-CLUSTERED IN BETWEEN THE UKMET AND CMC SOLUTIONS, SO A BLEND
OF THESE MODELS WILL BE PREFERRED.
..SOUTHERN STREAM TROUGH MOVING INTO CA BY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ARE IN VERY GOOD AGREEMENT WITH THIS ENERGY, AND THUS A
GENERAL MODEL BLEND WILL BE PREFERRED.
..UPPER TROUGH APPROACHING THE PACIFIC NORTHWEST WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE
A RELATIVELY DEEP TROUGH WILL BE APPROACHING THE PACIFIC NORTHWEST
BY LATE WEDNESDAY AND THE MODELS ARE OVERALL IN VERY GOOD
AGREEMENT WITH THEIR TIMING AND DEPTH. HOWEVER, THE 00Z NAM IS NOW
A TAD ON THE STRONG SIDE WITH ITS HEIGHT FALLS COMPARED TO THE
WELL-CLUSTERED GLOBAL MODELS. THEREFORE, A NON-NAM BLEND WILL BE
PREFERRED WITH THIS NEXT TROUGH.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
THIS PRODUCT WILL TERMINATE AUGUST 15, 2020:
WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERMINATION.
ORRISON
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