842
FXUS10 KWNH 031846
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
145 PM EST SUN NOV 03 2019
VALID NOV 03/1200 UTC THRU NOV 07/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
..12Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
PREFERENCE: GENERAL MODEL BLEND, DECREASING WEIGHT TO 12Z GFS/NAM
AFTER MONDAY AFTERNOON (05.00Z)
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
---18Z UPDATE---
NO CHANGE TO THE PRELIMINARY PREFERENCE. THE 12Z ECMWF DID TREND
LOWER WITH HEIGHTS ACROSS THE SOUTHERN TIER OF STATES ON DAY 3,
WHICH IS IN BETTER AGREEMENT WITH THE GFS. THIS LIKELY REQUIRES
LESS OF A DECREASE TO THE WEIGHT APPLIED TO THE 12Z NAM AND GFS
THAN THE PRELIMINARY DISCUSSION SUGGESTS.
---PREVIOUS DISCUSSION---
MODELS CONTINUE TO EXHIBIT STRONG AGREEMENT ON THE SYNOPTIC
PATTERN WITH MOST DETERMINISTIC MODELS WELL WITHIN THE ENVELOPE OF
THE NAEFS+ECMWF ENSEMBLE SPREAD. ECMWF ENSEMBLE SPREAD IS NEAR OR
BELOW THE 30-DAY AVERAGE OVER MOST OF THE CONUS, AND THESE FACTORS
LEAD TO SOMEWHAT HIGHER FORECAST CONFIDENCE. THE MODEL PREFERENCE
IS FOR A GENERAL MODEL BLEND.
BY MONDAY NIGHT, THE 12Z NAM AND GFS BEGIN TO EXHIBIT SOME SMALL
DEVIATIONS FROM MODEL CONSENSUS. THEY EJECT A SHORTWAVE THROUGH
THE NORTHEAST ON TUESDAY FASTER THAN THE OTHER GLOBAL MODELS, AND
ALSO SHOW A FLATTER FLOW PATTERN DOWNSTREAM OF A CLOSED UPPER
LEVEL LOW OVER THE SOUTHWEST. BY WEDNESDAY, THEY ARE FORECASTING
LOWER HEIGHTS ALOFT OVER MUCH OF THE SOUTHERN TIER OF THE COUNTRY.
THIS DOES AFFECT SOME OF THE QPF MAGNITUDE AND DISTRIBUTION ON
BOTH OF THE MODELS. FOR INSTANCE, ALONG COASTAL NEW ENGLAND, THE
GFS IS CONSIDERABLY DRIER, WHILE THE REMAINING MODELS HAVE TRENDED
TOWARD THE ECMWF WHICH HAS BEEN WETTER FOR SEVERAL MODEL CYCLES.
WITH MORE CONSISTENCY FROM THE ECMWF AND ECMWF ENSEMBLE AND MODEL
TRENDS IN THAT DIRECTION, THE PREFERENCE IS TO PLACE DECREASING
WEIGHT ON THE GFS AND NAM BEYOND MONDAY AFTERNOON.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
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