070
FXUS10 KWNH 071725
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1236 PM EDT WED AUG 07 2019
VALID AUG 07/1200 UTC THRU AUG 11/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS MODEL EVALUATION WITH INITIAL PREFERENCES AND
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
MODEL MASS FIELDS ARE IN VERY GOOD AGREEMENT INTO FRIDAY NIGHT,
WITH THE MAIN ISSUES WITH QPF ON PLACEMENT AND MAGNITUDE ALONG A
SLOW MOVING COLD FRONT OVER THE SOUTH-CENTRAL CONUS ON FRIDAY AND
AHEAD OF ANOTHER COLD FRONT OVER THE NORTHERN PLAINS ON SATURDAY.
A BROAD-BASED MODEL BLEND IS PREFERRED FOR MASS FIELDS WITH HIGHER
RESOLUTION FOR QPF GIVEN THEIR ABILITY TO PLACE CONVECTIVE PRECIP
FARTHER TOWARD INSTABILITY POOLS.
A COLD FRONT STALLS OVER THE SOUTH-CENTRAL CONUS LATE FRIDAY WITH
ASSOCIATED PRECIP FOR DAY 2 VARIED IN PLACEMENT AND MAGNITUDE
ALONG THIS FRONT. ONE NOTE IS THE 06Z GEFS QPF MEAN AND 00Z ECENS
QPF MEAN ARE THE FARTHEST NORTH WHILE OPERATIONAL RUNS OF THOSE
MODELS AS WELL AS OTHER DETERMINISTIC GUIDANCE ARE FARTHER SOUTH
TOWARD INSTABILITY. HOWEVER, THE 3KM NAM NEST IS IN SIMILAR
LATITUDE (NORTHERN OK/AR) AS THE GFS/ECMWF, SO THE ANSWER IS NOT
SIMPLY FARTHER SOUTH. A BROAD BASED MODEL APPROACH TO QPF IS
RECOMMENDED TO ACCOUNT FOR DIFFERENCES IN THE FRONTAL PLACEMENT
WHICH WILL BE DETERMINED BY CONVECTIVE PROCESSES.
DIFFERENCES IN THE SYNOPTIC SCALE BEGIN TO EMERGE FRIDAY NIGHT
WITH THE PROGRESSION OF A TROUGH INTO THE WEST COAST. THE 12Z GFS
IS THE MOST PROGRESSIVE INLAND WHICH WOULD CREATE DIFFERENCES IN
SHORTWAVE TROUGH PROGRESSION DOWNSTREAM AROUND THE NORTHERN HIGH
PLAINS RIDGE AXIS TO THE TROUGH OVER THE NORTHEAST CONUS. HOWEVER,
LITTLE QPF DIFFERENCE IS NOTED BETWEEN THE 12Z GFS AND OTHER
12Z/00Z GUIDANCE, SO A GENERAL MODEL BLEND IS RECOMMENDED.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
JACKSON
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