893
FXUS10 KWNH 151645
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 PM EDT WED JUL 15 2020
VALID JUL 15/1200 UTC THRU JUL 19/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...LONG WAVE TROUGH CROSSING THE NORTH CENTRAL US THROUGH THU WITH
AN ACCOMPANYING SURFACE COLD FRONT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE MODEL CONSENSUS TAKING THE BROAD
LONG WAVE TROUGH FROM THE UPPER MS VALLEY THIS AFTERNOON INTO
WESTERN QUEBEC FRI MORNING, THOUGH THE 12Z GFS MIGHT BE A BIT
FASTER THAN THE CONSENSUS AT THIS POINT. THERE IS ALSO GOOD
CLUSTERING WITH THE TIMING OF THE ASSOCIATED SURFACE COLD FRONT,
THOUGH THE 12Z GFS MIGHT BE A BIT FASTER THAN THE CONSENSUS
REACHING THE NORTHEAST FRI AFTERNOON.
HOWEVER, NONE OF THE MODEL DIFFERENCES WERE SIGNIFICANT ENOUGH TO
KEEP THEM OUT OF THE PREFERRED BLEND. DUE TO THE GOOD CLUSTERING,
FORECAST CONFIDENCE HAS INCREASED WITH THIS MODEL CYCLE.
..CUT OFF LOW WEST OF CALIFORNIA BY THURSDAY MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
BOTH THE 12Z NAM/GFS ARE CLOSE TO THE MODEL CONSENSUS WITH THE
DEVELOPMENT OF A CLOSED MID LEVEL LOW JUST OFF THE SOUTHWESTERN CA
COAST LATE THU INTO EARLY FRI. THEY ARE ALSO CLOSE WITH TAKING THE
MID LEVEL SYSTEM WEST INTO THE PACIFIC WITH TIME. SINCE PLACEMENT
AND TIMING DIFFERENCES ARE FAIRLY MINOR, A GENERAL MODEL BLEND IS
PREFERRED WITH THIS SYSTEM.
...LONG WAVE TROUGH CROSSING THE PACIFIC NORTHWEST THU, MOVING
INTO SOUTH CENTRAL CANADA BY SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z NAM BLEND
CONFIDENCE: AVERAGE
THERE IS GENERALLY MODEL MODEL CLUSTERING WITH THE LONG WAVE
TROUGH THAT CROSSES THE PACIFIC NORTHWEST THU MORNING. AS THE
TROUGH MOVES INTO MANITOBA/SASKATCHEWAN SAT INTO SUN, MODEL SPREAD
DEVELOPS WITH RESPECT TO TIMING. WHILE ALL OF THE MOST RECENT
MODEL SOLUTIONS SLOW THE TROUGH AS IT REACHES CENTRAL CANADA, THE
12Z NAM CONTINUES IT'S MODEL TREND OF BEING SLOWER THAN THE
CONSENSUS, ESPECIALLY BY 12Z SUN.
A COLD FRONT ASSOCIATED WITH THE TROUGH EXTENDS FROM THE UPPER MS
VALLEY INTO THE CENTRAL PLAINS BY THAT TIME. AGAIN, THE 12Z NAM IS
SLOWER WITH THE FRONT; OTHERWISE THERE IS GOOD CLUSTERING WITH THE
PLACEMENT OF THE FRONT BY THE END OF THE PERIOD. BASED ON THE
ABOVE, A NON 12Z NAM BLEND IS PREFERRED. DUE TO THE INCREASE IN
SPREAD ACROSS CENTRAL CANADA WITH THE LONG WAVE TROUGH, FORECAST
CONFIDENCE IS ONLY AVERAGE.
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.
HAYES
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