209
FXUS10 KWNH 100509
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
108 AM EDT FRI JUL 10 2020
VALID JUL 10/0000 UTC THRU JUL 13/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...MID-LEVEL SHORTWAVE CROSSING THE GREAT LAKES/OHIO VALLEY
THROUGH SAT...
..ASSOCIATED COLD FRONT CROSSING THE GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/12Z ECMWF BLEND
CONFIDENCE: BELOW AVERAGE
RUN TO RUN CONSISTENCY HAS BEEN POOR WITH THIS SYSTEM AND THE
CHANGES SEEN IN THE 12Z/10 ENSEMBLE SPAGHETTI PLOTS COMPARED TO
THE PREVIOUS 00Z/10 CYCLE ARE DRAMATIC VALID SATURDAY MORNING. THE
LATEST CONSENSUS IS NEAR THE AGREEABLE GEFS/EC ENSEMBLE MEANS
WHICH SHOW THE MID-LEVEL TROUGH PROGRESSING SLOWER THAN THE 00Z
GFS. A BLEND OF THE 00Z NAM (WEAKER/NORTH) AND 12Z ECMWF
(STRONGER/SOUTH) MAY BE THE BEST COMPROMISE AS NO SINGLE MODEL
SOLUTION LOOKS IDEAL HERE. THE 12Z CMC IS WEAKER AND FASTER THAN
THE ENSEMBLE MEANS WITH THE MID-LEVEL TROUGH WHILE THE 12Z UKMET
IS RATHER STRONG AND NORTH WITH THE MID-LEVEL LOW CENTER.
..TROPICAL STORM FAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/12Z ECMWF/12Z CMC BLEND IS CLOSEST TO 03Z NHC
ADVISORY
CONFIDENCE: REFER TO NHC
THE DETERMINISTIC MODELS VARY WITH CLOSENESS TO THE 03Z NHC
ADVISORY FOR FAY OVER THE NEXT 48 HOURS. HOWEVER, OVERALL, A BLEND
OF THE 00Z NAM/12Z ECMWF AND 12Z CMC IS NEAREST TO THE TRACK FOR
FAY AS THE STORM MOVES INTO THE NORTHEAST FRIDAY NIGHT. THE
NAM/ECMWF COMBINATION FALLS A BIT WEST OF THE NHC TRACK, AND A
POSSIBLE OVER AMPLIFICATION OF AN UPSTREAM (OH VALLEY) TROUGH SEEN
IN THE 12Z ECMWF MAY BE TO BLAME AS DISCUSSED IN THE ABOVE SECTION.
...MID-LEVEL SHORTWAVE TO CROSS THE NORTHERN ROCKY MOUNTAINS EARLY
FRIDAY MORNING, MOVE ATOP THE RIDGE AND INTO THE UPPER MIDWEST BY
SAT EVENING, REACHING THE OH VALLEY ON SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z ECMWF BLEND
CONFIDENCE: AVERAGE
THE 00Z NAM/GFS ARE CLOSE TO ONE ANOTHER WITH THIS SYSTEM AS IT
NEARS THE MISSISSIPPI RIVER, BUT TEND TO BE A LITTLE SLOWER THAN
THE ENSEMBLE MEANS. MEANWHILE THE 12Z UKMET/CMC ARE SOUTH OF THE
ENSEMBLE MEANS. A BLEND OF THESE MODELS MAY BE BEST FOR THIS
SYSTEM WITH ONLY THE WEAKLY DEFINED 12Z ECMWF STANDING OUT
SIGNIFICANTLY FROM THE REMAINING CONSENSUS.
...LONGWAVE TROUGH AXIS MOVING INTO WESTERN CANADA AND THE
NORTHWESTERN U.S. ON SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
WITH ONLY MINOR TIMING DIFFERENCES NOTED WITH A LARGE TROUGH AXIS
REACHING THE NORTHWESTERN U.S. THIS WEEKEND, A GENERAL MODEL BLEND
WILL WORK WELL FOR THE PREFERENCE.
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 WITH THE 21Z ISSUANCE:
WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERMINATION.
OTTO
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