421
FXUS10 KWNH 061623
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1222 PM EDT MON JUL 06 2020
VALID JUL 06/1200 UTC THRU JUL 10/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z GFS/NAM EVALUATION WITH PRELIMINARY MODEL
PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.
NEW TROUGH MOVING INTO THE PACIFIC NORTHWEST THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE
OUTSIDE OF THE QUICK 12Z NAM, THE GUIDANCE SHOWS GOOD AGREEMENT
WITH THE DEPTH AND PROGRESSION OF THIS FEATURE INTO THURSDAY
AFTERNOON. A COMPROMISE OF THE 12Z GFS, 00Z ECMWF, 00Z UKMET, AND
00Z CANADIAN IS PREFERRED (WHICH BEST FITS IN THE 06Z GEFS/00Z
ECMWF ENSEMBLE MEAN SOLUTIONS) WITH ABOVE AVERAGE CONFIDENCE.
CLOSED LOW MOVING EAST ALONG THE WESTERN & CENTRAL US/CANADIAN
BORDER
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS FEATURE MOVING EAST
FROM THE PACIFIC NORTHWEST THROUGH TUESDAY NIGHT BEFORE THE 12Z
NAM BECOMES A SLOW/DEEP OUTLIER IN SOUTH-CENTRAL CANADA -- ITS
TRADITIONAL BIAS. SINCE THE FLOW PATTERN IN WHICH IT IS EMBEDDED
IS FAIRLY ZONAL, WILL PREFER A COMPROMISE OF THE 12Z GFS, 00Z
ECMWF, 00Z UKMET, AND 00Z CANADIAN (WHICH BEST FITS IN THE 06Z
GEFS/00Z ECMWF ENSEMBLE MEAN SOLUTIONS) WITH ABOVE AVERAGE
CONFIDENCE.
DEEP LAYER CYCLONE EDGING EAST-NORTHEAST NEAR THE VA/NC BORDER
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CANADIAN COMPROMISE
CONFIDENCE: ABOVE AVERAGE
A DEEP LAYER CYCLONE IS EXPECTED TO MOVE SLOWLY EAST-NORTHEAST AS
A MID-LEVEL RIDGE BUILDS TO THE NORTH ACROSS THE NORTHERN
APPALACHIANS AND NEW ENGLAND. THE 00Z CANADIAN WAS NORTH OF THE
OTHER GUIDANCE WHILE THE 00Z UKMET WAS THE MOST EASTWARD/QUICKEST.
THE PROGRESSIVE RIDGE MOVING OVER THE TOP OF THE SYSTEM ARGUES
FOR SLOWLY PROGRESSION THAN THE UKMET. THE APEX OF THE NORTHERN
STREAM RIDGE (56-57N) ARGUES FOR THE LATITUDE OF THE CLOSED
CYCLONE UNDERNEATH FOR BE CENTERED IN THE 36-37N RANGE, SOUTH OF
THE 00Z CANADIAN. WILL PREFER A COMPROMISE OF THE 12Z GFS, 12Z
NAM, 00Z UKMET, AND 00Z ECMWF (WHICH NATURALLY WEIGHTS TOWARDS THE
SLOWER GUIDANCE) WITH ABOVE AVERAGE CONFIDENCE.
SHORTWAVE TROUGH MOVING BY NEW ENGLAND WEDNESDAY
PERSISTENT 700 HPA TROUGH ACROSS NV/CA THROUGH THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THE PROGRESSION AND DEPTH
OF THESE FEATURES, SO PREFER A COMPROMISE OF THE 12Z NAM, 12Z GFS,
00Z UKMET, 00Z CANADIAN, AND 00Z ECMWF WITH ABOVE AVERAGE
CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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