863
FXUS10 KWNH 080627
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
226 AM EDT SUN SEP 08 2019
VALID SEP 08/0000 UTC THRU SEP 11/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND; LESS WEIGHT ON 00Z GFS/NAM
CONFIDENCE: AVERAGE
---06Z UPDATE---
NO CHANGE TO THE PRELIMINARY PREFERENCE. WITH THE ARRIVAL OF THE
REMAINDER OF THE 00Z DETERMINISTIC MODEL RUNS, THE 00Z GFS SEEMS
TO BE FURTHER EAST WITH THE POSITION OF THE WESTERN U.S. TROUGH
THAN ANY OF THE OTHER MODELS INCLUDING THE GEFS MEAN. FOR THIS
REASON, LESS WEIGHT WILL CONTINUE TO BE PLACED ON THE GFS AND THE
NAM (WHICH IS MORE AMPLIFIED WITH THE TROUGH RELATIVE TO OTHER
MODELS).
---PREVIOUS DISCUSSION---
MODELS ARE IN GOOD AGREEMENT ON AN AMPLIFICATION OF THE SYNOPTIC
PATTERN ACROSS THE CONUS OVER THE NEXT SEVERAL DAYS, WITH A TROUGH
IN THE WESTERN U.S. AND A RIDGE IN THE EAST. THE DETERMINISTIC
MODELS ARE REASONABLY WELL CLUSTERED AND HEIGHTS AT SEVERAL
PRESSURE LEVELS ARE WITHIN THE ENSEMBLE ENVELOPE. THE ECMWF
ENSEMBLE 500MB HEIGHT SPREAD IS GENERALLY NEAR OR LESS THAN THE
PREVIOUS 30 DAY AVERAGE IN MOST AREAS, WITH THE EXCEPTION OF THE
BASE OF THE TROUGH IN THE WESTERN U.S. (RELATED TO UNCERTAINTY ON
THE AMPLITUDE OF THE TROUGH). GIVEN THESE FACTORS, A GENERAL MODEL
BLEND IS PREFERRED IN MOST AREAS.
ONE OF THE LARGER QPF DIFFERENCES EXISTS OVER THE MID-MISSISSIPPI
VALLEY AND INTERIOR SOUTHEAST. THE 00Z GFS AND NAM SHOW MORE
WIDESPREAD AND HEAVIER RAINFALL ON TUESDAY AND TUESDAY NIGHT IN
THESE REGIONS, WHILE THE OTHER GLOBAL MODELS HAVE LIMITED
RAINFALL. THE PREFERENCE IN THESE AREAS IS TO LEAN TOWARD THE 12Z
ECMWF, CMC AND UKMET, AS THE REGION WILL BE UNDERNEATH AN
EXPANDING RIDGE. WHILE SOME CONVECTIVE RAINFALL IS POSSIBLE, THE
BLEND WILL BE WEIGHTED TOWARD MODELS SHOWING DRIER SCENARIOS.
OTHERWISE, MODEL PRECIPITATION FORECASTS ARE FAIRLY SIMILAR, WHICH
IS CONSISTENT WITH THE OVERALL AGREEMENT WITH THE MASS FIELDS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
LAMERS
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