025
FXUS10 KWNH 010655
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 AM EDT SAT AUG 01 2020
VALID AUG 01/0000 UTC THRU AUG 04/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..MID-LEVEL TROUGH DIGGING ACROSS THE MID-MS/TN/OH VALLEYS
..SURFACE LOW CROSSING THE OH VALLEY/LOWER GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/GFS/UKMET
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
MID-LEVEL ENERGY DIGGING SOUTHEAST ACROSS THE MID-MS VALLEY WILL
DRIVE A TROUGH IN ACROSS MUCH OF THE TN/OH VALLEY GOING THROUGH
THE WEEKEND. THIS WILL BE REINFORCED BY SUNDAY BY AN INTRUSION OF
NORTHERN STREAM TROUGHING DROPPING DOWN ACROSS THE GREAT LAKES
REGION BUT A LEAD SHORTWAVE WITHIN THE INITIAL TROUGHING WILL
COINCIDE WITH A SURFACE LOW TRACKING ACROSS THE MS RIVER VALLEY
INTO THE OH VALLEY AND EVENTUALLY THE LOWER GREAT LAKES AND
SOUTHEASTERN CANADA THROUGH SUNDAY NIGHT.
THE 00Z NAM/GFS SOLUTIONS AND THE 00Z NON-NCEP CAMP OF GUIDANCE
ARE MOSTLY IN STRONG AGREEMENT ON THE SYNOPTIC SCALE SET-UP, ALONG
WITH THE DETAILS OF THE EJECTING SHORTWAVE AND ATTENDANT SURFACE
LOW. HOWEVER, THE 00Z CMC GRADUALLY BECOMES A WEAKER OUTLIER WITH
THE SHORTWAVE ENERGY AND SURFACE LOW AND WILL BE DISMISSED.
ADDITIONALLY, FROM ABOUT 36 HOURS ONWARD, THE 00Z ECMWF BEGINS TO
OUTPACE EVERY OTHER PIECE OF GUIDANCE WITH THE FORWARD PROGRESSION
OF THIS SYSTEM. THE 00Z GEFS MEAN AND YESTERDAY'S 12Z ECENS MEAN
ARE STRONGLY SUPPORTIVE OF THE WELL-CLUSTERED 00Z NAM/GFS/UKMET
SOLUTIONS, SO A CONSENSUS OF THE LATTER CAMP WILL BE PREFERRED.
..HURRICANE ISAIAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 03Z NHC ADVISORY PACKAGE
BEST MODEL PROXY: 00Z GFS
THE 03Z NHC FORECAST TRACK OF HURRICANE ISAIAS IS GENERALLY FASTER
AND TO THE RIGHT OF ALL OF THE NON-NCEP GUIDANCE (I.E. 00Z
ECMWF/UKMET/CMC SOLUTIONS) FROM 24 HOURS ONWARD, AND IS GENERALLY
CLOSEST TO 00Z NAM/GFS BLEND THROUGH 48 HOURS. AFTER 48 HOURS, THE
NHC TRACK IS CLOSEST ULTIMATELY TO THE 00Z GFS, BUT THEN ENDS MUCH
BEING NOTABLY FASTER AS THE 00Z GFS ALONG WITH THE REMAINING MODEL
SUITE HAVE BEEN TRENDING SLOWER WITH THE SYSTEM'S ULTIMATE
RECURVATURE TO THE NORTH AND NORTHEAST AHEAD OF THE UPPER TROUGH
MOVING INTO THE OH/TN VALLEYS OVER THE NEXT COUPLE OF DAYS. THE
00Z HREF SUITE OF GUIDANCE ON THE OTHER HAND, MINUS THE NMMB,
TAKES ISAIAS TO THE RIGHT OF THE NHC TRACK THROUGH 48 HOURS.
PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY/DISCUSSION FOR
MORE DETAILS.
..NORTHERN STREAM TROUGH SETTING UP OVER THE GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
NORTHERN STREAM ENERGY WILL BE DIGGING DOWN ACROSS THE GREAT LAKES
REGION THIS WEEKEND WITH SUGGESTION OF AN ELONGATED CLOSED LOW
DEVELOPING A BIT FARTHER NORTH OVER ONTARIO BY MONDAY AND TUESDAY.
THE GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THE FULL 00Z
CYCLE, AS THE CMC/UKMET SOLUTIONS TRENDED TOWARD THE 00Z NAM WITH
PLACEMENT OF THE CLOSED LOW AT THE END OF THE PERIOD. THE 00Z
GFS/ECMWF SOLUTIONS ARE A TAD MORE ELONGATED OFF TO THE NORTHEAST
ACROSS AREAS OF SOUTHEAST CANADA, BUT GIVEN THE BETTER CLUSTERING
SEEN AT THIS POINT, A GENERAL MODEL BLEND WILL BE PREFERRED.
..UPPER LOW/TROUGH APPROACHING THE PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: AVERAGE
MODEL DIFFERENCES SHOW UP WITH THE TROUGH AXIS AS IT NEARS BRITISH
COLUMBIA AND THE PACIFIC NORTHWEST LATE ON SUNDAY AND THEN
ADVANCES INLAND ACROSS THE FAR NORTHERN ROCKIES AND ADJACENT AREAS
OF SOUTHWEST CANADA ON MONDAY. THE 00Z CMC ENDS UP BEING ON THE
WEAKER AND MORE PROGRESSIVE SIDE OF THE GUIDANCE AS THE ENERGY
ADVANCES INLAND. THE 00Z UKMET AND 00Z ECMWF BOTH GRADUALLY END UP
A LITTLE SLOWER THAN THE 00Z NAM AND 00Z GFS, BUT THESE SOLUTIONS
HAVE TRENDED TOWARD EACH OTHER WITH THIS CYCLE AND SUGGEST A SMALL
CLOSED LOW ADVANCING EAST ACROSS FAR SOUTHWEST CANADA GOING
THROUGH EARLY TUESDAY. WILL STILL PREFER A NON-CMC BLEND FOR THE
TIME BEING.
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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