793
FXUS10 KWNH 291701
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
100 PM EDT WED JUL 29 2020
VALID JUL 29/1200 UTC THRU AUG 02/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES AND
FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..MID-UPPER LEVEL TROUGHING OVER THE GREAT LAKES AND NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
ONLY MINOR TIMING DIFFERENCES WERE NOTED WITH THIS SYSTEM, SUCH
THAT A GENERAL MODEL BLEND CAN BE USED THROUGH SATURDAY.
..ENERGY ADVANCING ACROSS THE PLAINS THROUGH THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/12Z GFS BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
MID-LEVEL ENERGY COMING OUT OF THE ROCKIES INTO THE CENTRAL PLAINS
SLOWLY SAGS SOUTHEASTWARD TOWARD THE OZARKS ON FRIDAY AND
ELONGATES WITH BROADER, LARGER SCALE TROUGHING ALONG THE MS RIVER
THROUGH THE GREAT LAKES REGION BY SATURDAY MORNING. THE MODELS
BEGIN TO DIVERGE WITH A MID-LEVEL VORTICITY MAX LOCATED NEAR THE
BASE OF THE TROUGH LATE FRIDAY. THERE ARE NO MODEL OUTLIERS, BUT
THE 00Z UKMET APPEARS TOO STRONG HERE. TIMING-WISE, THE MIDDLE OF
THE GUIDANCE IS FAVORED, WITH THE 12Z GFS/NAM CLOSEST TO THE
MIDDLE OF THE SPREAD. THE 00Z ECMWF/CMC ARE FASTER, ESPECIALLY THE
00Z CMC...WHILE THE 00Z UKMET IS SLIGHTLY SLOWER AND MUCH STRONGER.
..UPPER LOW/TROUGH APPROACHING THE PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THERE ARE NO SIGNIFICANT DIFFERENCES NOTED WITH THIS SYSTEM.
...POTENTIAL TROPICAL CYCLONE NINE APPROACHING SOUTHERN FLORIDA
AROUND SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/00Z CMC CLOSEST TO 15Z NHC ADVISORY
CONFIDENCE: REFER TO NHC PRODUCTS
POTENTIAL TROPICAL CYCLONE (PTC) NINE WILL TRACK FROM NEAR THE
U.S. VIRGIN ISLANDS WESTWARD TOWARD CUBA AND SOUTHERN FLORIDA
THROUGH SATURDAY. MODEL SPREAD VARIES CONSIDERABLY WITH THIS
FEATURE WITH A SOMEWHAT SOUTHWESTERN TREND WAS NOTED IN THE LAST
FEW CYCLES OF ENSEMBLE LOW PLOTS. THE BEST MODEL PROXY TO THE
OFFICIAL NHC FORECAST FROM 15Z IS A BLEND OF THE 12Z NAM AND 00Z
CMC. A 50/50 BLEND OF THE NORTHERN 12Z GFS POSITION AND SOUTHERN
00Z ECMWF POSITION ALSO YIELDS CLOSE TO THE NHC TRACK. MEANWHILE
THE 00Z UKMET APPEARS TO BE SLOWER THAN THE NHC ADVISORY. FOR THE
LATEST INFORMATION ON PTC NINE, PLEASE SEE THE UPDATED NHC
ADVISORY.
...COLD FRONT MOVING THROUGH THE NORTH-CENTRAL U.S. FRIDAY AND
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THERE IS RELATIVELY GOOD AGREEMENT FOR THE TROUGH AXIS AND RELATED
COLD FRONT IMPACTING THE NORTH-CENTRAL U.S. THROUGH SATURDAY.
WHILE MINOR TIMING DIFFERENCES ARE EVIDENT, SUCH AS THE 12Z GFS
BEING SLOWER, THE DIFFERENCES ARE SMALL ENOUGH FOR A 60 TO 84 HOUR
FORECAST TO ALLOW FOR A GENERAL MODEL BLEND AT THIS TIME.
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.
OTTO
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