958
FXUS10 KWNH 300457
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1257 AM EDT FRI AUG 30 2019
VALID AUG 30/0000 UTC THRU SEP 02/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z PRELIMINARY EVALUATION, CONFIDENCE, AND PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z CMC WITH SOME 12Z ECMWF BLEND
CONFIDENCE: AVERAGE THROUGH 48 HOURS, SLIGHTLY BELOW AVERAGE DAY 3
THROUGH THE FIRST 48 HOURS, THE GUIDANCE IS IN VERY GOOD AGREEMENT
THAT A BROAD LONGWAVE TROUGH WILL PERSIST IN THE EAST, WHILE
RIDGING CONTINUES IN THE WEST. SMALL SCALE DISTURBANCES WITHIN THE
FLOW MAY CAUSE PERIODIC ROUNDS OF CONVECTION OF WHICH THE MODELS
DIFFER ON LATITUDINAL PLACEMENT AND QPF, BUT REALLY ONLY THE NAM
IS AN OUTLIER BY BEING TOO DEEP WITH ITS TROUGH. BY DAY 3, THE
GUIDANCE DIFFERS CONSIDERABLY WITH HANDLING OF A MID-LEVEL TROUGH
APPROACHING THE PACNW. THE NAM/UKMET CLOSE OFF THE LOW TO MAINTAIN
A POSITIVELY TILTED TROUGH AXIS WEST OF THE CONUS, THE CMC/GFS
MOVE A WEAKER SHORTWAVE ONSHORE WA/BC, WHILE THE ECMWF IS
SOMEWHERE IN BETWEEN. THE DIFFERENCES SEEM TO ARISE FROM VASTLY
DIFFERENT JET INTENSITIES AND PLACEMENT AS NO FEWER THAN 3 JET
STREAKS INTERACT OVER THE NORTHERN PACIFIC OCEAN. THE GFS/CMC SEEM
TO HANDLE THE CROSS POLAR JET MOST SIMILARLY, BUT CONFIDENCE IS
REDUCED BY DAY 3.
..HURRICANE DORIAN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PLEASE REFER TO THE OFFICIAL NATIONAL HURRICANE CENTER FORECAST
TRACK
THE 12Z CMC AND 00Z GFS ARE MOST CLOSELY ALIGNED TO THE 03Z NHC
TRACK, BUT THE GFS QPF SEEMS MOST REALISTIC FOR A TROPICAL SYSTEM
IN THE BAHAMAS. THE NAM/ECMWF LAG THE TRACK, WHILE THE UKMET IS
SEVERAL DEGREES OF LONGITUDE TOO FAST. FOR NOW THEN, A CMC/GFS
BLEND IS PREFERRED FOR DORIAN TO MAINTAIN THE BEST TRACK
INTEGRITY, WITH SUBTLY MORE WEIGHT ON THE GFS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
WEISS
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