627
FXUS10 KWNH 160415
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1214 AM EDT THU JUL 16 2020
VALID JUL 16/0000 UTC THRU JUL 19/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST 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 00Z GFS TRENDED A BIT WEAKER WITH THE WAVE CROSSING THE GREAT
LAKES TONIGHT AND FALLS WELL WITHIN THE OVERALL TIGHT PACKING IN
THE MODEL MASS FIELDS. THIS CONTINUES AS IT PROGRESSES ACROSS NEW
ENGLAND. THE 00Z NAM IS A BIT DEEPER, RETAINS SOME AMPLIFICATION
AS IT FLATTENS, RELATIVE TO THE REMAINING GUIDANCE SUITE BUT NOT
ENOUGH TO REMOVE IT FROM THE PREFERENCE. AS SUCH, WILL MAINTAIN A
GENERAL MODEL BLEND WITH CONFIDENCE REMAINING SLIGHTLY ABOVE
AVERAGE.
..CUT OFF LOW WEST OF CALIFORNIA BY THURSDAY MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE 00Z NAM/GFS CONTINUE TO BE CLOSE THE 12Z UKMET/ECMWF/CMC RUNS
WITH THE WEAKNESS BETWEEN THE ZONAL/BROAD SUBTROPICAL RIDGE ACROSS
THE SOUTHEAST TO THE SOUTHWEST AND THE STRONGER EAST/CENTRAL
PACIFIC RIDGE. THE WAVE CONTINUES TO SHEAR/RETROGRADE UNDER THE
PACIFIC RIDGE WITH SOME ENERGY SHIFTING INTO THE PACIFIC NW WITH
LITTLE FANFARE. AS SUCH, A GENERAL MODEL BLEND WILL CONTINUE TO
BE PREFERRED WITH THIS SYSTEM AT ABOVE AVERAGE CONFIDENCE.
...LONG WAVE TROUGH CROSSING THE PACIFIC NORTHWEST THU, MOVING
INTO SOUTH CENTRAL CANADA BY SAT, CLIPPING THE NORTHERN PLAINS
INTO UPPER GREAT LAKES BY SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND, REDUCE NAM WEIGHTING AFTER 19.00Z
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE LEADING EDGE OF HEIGHT-FALLS CLIPS THE PACIFIC NORTHWEST ON
THURSDAY AS THE CORE OF THE UPPER LEVEL-LONG WAVE TROF TRACKS EAST
ACROSS NORTHERN BC/ALBERTA. THE WAVE DESCENDS IN LATITUDE AFTER
CROSSING THE CANADIAN ROCKIES, WHICH WILL HELP DROP A FRONTAL ZONE
ACROSS THE NORTHERN TIER. HERE, THE MASS FIELDS ARE IN FAIRLY
GOOD AGREEMENT IN TIMING; ONLY THE 12Z CMC APPEARS A BIT OUT OF
PLACE EVENTUALLY MOVING OUT OF TOLERANCE (GENERALLY A BIT SOUTH
WITH THE SURFACE LOW IN CANADA AND NORTH ACROSS THE CENTRAL HIGH
PLAINS) BY 72HRS. THE 00Z NAM, PERHAPS DUE TO HIGHER GRID SCALE,
SUGGESTS A STRONGER, HIGHER CONVECTIVE CLUSTERING/QPF RESULT
ACROSS THE UPPER MIDWEST AS THE FRONT PRESSES THROUGH. THIS FALLS
IN LINE WITH TYPICAL END OF DAY 3 BIAS, BUT IS NOT DRAMATIC ENOUGH
TO SUGGEST IT IS NOT IN THE REALM OF PROBABILITY. AS SUCH WILL
SUPPORT A NON-CMC BLEND OVERALL AT SLIGHTLY ABOVE AVERAGE
CONFIDENCE, BUT REDUCING INFLUENCE OF THE NAM AFTER 19.00Z.
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.
GALLINA
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