116
FXUS10 KWNH 100818
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
417 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 MODEL EVALUATION WITH FINAL PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...MID-LEVEL SHORTWAVE CROSSING THE GREAT LAKES/OHIO VALLEY
THROUGH SAT...
..ASSOCIATED COLD FRONT CROSSING THE GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z GFS BLEND
CONFIDENCE: BELOW AVERAGE
07Z UPDATE...THERE IS BETTER AGREEMENT WITH THE MID-LEVEL
SHORTWAVE FROM THE 00Z ECMWF/UKMET/CMC, WHICH SHOW THE 00Z GFS OUT
ON ITS OWN WITH A FASTER TRACK AS THE VORT CENTER TRACKS INTO THE
NORTHEAST.
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: GENERAL MODEL BLEND THROUGH 12Z/11 CLOSEST TO 03Z NHC
ADVISORY
00Z ECMWF/UKMET BLEND 12Z/11-12Z/12 CLOSEST TO 03Z NHC
ADVISORY
CONFIDENCE: REFER TO NHC
07Z UPDATE...THE 00Z ECMWF/UKMET ADJUSTED FASTER, CLOSER TO THE
03Z NHC ADVISORY, LEAVING THE 00Z DETERMINISTIC CONSENSUS FAIRLY
CLOSE TO THE 03Z NHC ADVISORY FOR THE TRACK OF FAY. BEYOND
SATURDAY MORNING, THE MODELS DIVERGE LEAVING THE 00Z ECMWF/UKMET
CLOSEST 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: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
07Z UPDATE...ADJUSTMENTS IN THE 00Z ECMWF TOWARD THE REMAINING
CONSENSUS SUPPORT BETTER AGREEMENT WITH THIS FEATURE AS IT CROSSES
THE MISSISSIPPI RIVER VALLEY. DESPITE SOME MINOR TIMING
DIFFERENCES, THE AGREEMENT IS GOOD ENOUGH AT THIS POINT TO SUPPORT
A GENERAL MODEL BLEND.
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
07Z UPDATE...ONLY MINOR TIMING ADJUSTMENTS WERE NOTED IN THE 00Z
ECMWF/UKMET/CMC COMPARED TO THEIR PREVIOUS 12Z CYCLES. GIVEN THE
MINOR DIFFERENCES NOTED WITH THE LARGE TROUGH AXIS REACHING THE
NORTHWESTERN U.S. THIS WEEKEND, A GENERAL MODEL BLEND WILL WORK
WELL HERE 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:
HTTPS://WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERM
INATION.PDF
OTTO
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