423
FXUS10 KWNH 080446
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1246 AM EDT THU AUG 08 2019
VALID AUG 08/0000 UTC THRU AUG 11/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
MODEL MASS FIELDS ARE IN VERY GOOD AGREEMENT THROUGH THE DAY ON
FRIDAY AND INTO EARLY FRIDAY NIGHT, WITH THE MAIN ISSUE BEING
SMALLER SCALE FEATURES WHICH IMPACT QPF PLACEMENT AND MAGNITUDE
ALONG A LOW MOVING COLD FRONT OVER THE SOUTH-CENTRAL CONUS.
SIMILAR DIFFERENCE APPEAR ONCE AGAIN AHEAD OF THE NEXT COLD FRONT
OVER THE NORTHERN PLAINS ON SATURDAY. A BROAD-BASED MODEL BLEND IS
PREFERRED FOR MASS FIELDS ACROSS NORTH AMERICA...WITH MORE FOCUS
ON HIGHER RESOLUTION GUIDANCE FOR QPF.
DIFFERENCES IN TWO PARTS OF NORTH AMERICA EMERGE FRIDAY
NIGHT/EARLY SATURDAY. ONE REGION IS OVER CENTRAL AND EASTERN
CANADA WITH IMPLICATIONS FOR THE MAGNITUDE AND SPEED OF
PROPAGATION OF A MID- AND UPPER-LEVEL TROUGH OVER NEW ENGLAND. THE
NAM WAS A SLOW/STRONG OUTLIER IN MOVING THE TROUGH FROM NEW YORK
ACROSS NEW ENGLAND ON SATURDAY...WHILE THE GFS WAS CLUSTERED WITH
OTHER OPERATIONAL AND ENSEMBLE MEANS.
THE SECOND AREA OF DIFFERENCES IN THE SYNOPTIC SCALE ON FRIDAY
NIGHT IS THE PROGRESSION OF A TROUGH INTO THE WEST COAST. IN THIS
CASE, THE 00Z GFS REMAINED THE MOST PROGRESSIVE...WHICH HAS
IMPLICATIONS IN THE SHORTWAVE TROUGH PROGRESSION DOWNSTREAM AROUND
THE NORTHERN HIGH PLAINS RIDGE AXIS TO THE TROUGH OVER THE
NORTHEAST CONUS. AM TEMPTED TO PUT LESS CONSIDERATION IN THE GFS
IDEA DUE TO CONVECTIVE FEEDBACK APPEARING IN THE MASS FIELDS ON
DAY 2...BUT THE IMPACTS IN TERMS OF QPF IS MINIMAL SUGGESTING THE
MODEL BLEND CAN INCLUDE THE GFS WITHOUT SIGNIFICANT PROBLEMS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
BANN
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