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Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1843Z Sep 29, 2014)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
243 PM EDT MON SEP 29 2014

VALID SEP 29/1200 UTC THRU OCT 03/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

==============================================
12Z MODEL EVALUATION AND PREFERENCES
==============================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==============================================

...CYCLOGENESIS IN THE NORTHERN PLAINS...

PREFERENCE: BLEND OF THE OPERATIONAL MODELS
CONFIDENCE: ABOVE AVERAGE

AT THE LEADING EDGE OF A LARGE SCALE TROUGH...A SMALLER SCALE
CYCLONE WILL EVOLVE OVER THE NORTHERN PLAINS BEFORE LIFTING INTO
CANADA. MODELS SHOW STRONG AGREEMENT AS TO THE DETAILS.


...SHORTWAVES DIGGING THROUGH THE ROCKIES AND PLAINS WED/THU...

PREFERENCE: 12Z GFS
CONFIDENCE: AVERAGE

THE FORECAST HERE IS MADE PARTICULARLY CHALLENGING BY EXISTENCE OF
A SPLIT STREAM WITHIN NORTHWESTERLY FLOW AND GROWING SEPARATION
BETWEEN THE GEFS MEAN AND THE LATEST AVAILABLE 00Z ECMWF ENSEMBLE
MEAN FOR FORECASTS VERIFYING 00Z FRIDAY. CONFIDENCE IN A GFS-LIKE
SOLUTION IS INCREASED...HOWEVER...BY DISTINCT TRENDS IN A HEALTHY
MAJORITY OF THE GUIDANCE. THE GFS AND NAM HAVE SHOWN AGREEMENT
WITH ONE ANOTHER AND RUN TO RUN CONSISTENCY IN THE 29/00Z TO
29/06Z AND 29/12Z RUNS. THEY ARE SUPPORTED BY THE GEFS MEAN AND
THE NAEFS MEAN WHICH INCORPORATES THE CANADIAN MODELING CENTER
ENSEMBLE. MORE RECENTLY THE 12Z UKMET TRENDED STRONGLY TOWARD THE
NAM/GFS. THE OPERATIONAL CANADIAN CONTINUES AS A DEEP OUTLIER
DEPICTING STRONG HEIGHT FALLS INTO SOUTHWEST TEXAS ON
THURSDAY...BUT IT DOES ERR ON THE SIDE OF SLOWER AND DEEPER.
VIEWING ALL THE GUIDANCE TOGETHER...THE ECMWF STILL APPEARS TO BE
A LESS LIKELY SOLUTION...BEING TOO FAST AND OF LESSER AMPLITUDE.
IT IS WORTH NOTING...HOWEVER...THAT THE 12Z ECMWF DID TREND
SLIGHTLY SLOWER.

OUR PREFERRED MODEL CLUSTER...THAT WHICH SUPPORT THE GFS...HAS
SHOWN A DISTINCT TREND TOWARD THE SLOWER AND MORE AMPLIFIED
SOLUTION IN THE SOUTHERN PLAINS...AND ALSO A BREAKDOWN OF
SHORTWAVE RIDGING ALONG THE WEST COAST OF BRITISH COLUMBIA
THURSDAY. ALTHOUGH PERHAPS NOT DIRECTLY RELATED...SEEING AGREEMENT
IN THE TRENDS AT TWO KEY PLACES ON THE MAP GIVES US INCREASED
CONFIDENCE THAT THE TRENDS ARE MEANINGFUL. WITH THE NAM/UKMET
BEING A BIT DEEPER/STRONGER IN THE PLAINS...WE RECOMMEND THE
SOMEWHAT MORE CONSERVATIVE 12Z GFS.


...SHORTWAVE TROUGH DIGGING INTO THE MID-ATLANTIC/SOUTHERN NEW
ENGLAND...

PREFERENCE: 12Z ECMWF
CONFIDENCE: ABOVE AVERAGE

HERE MODEL DIFFERENCES ARE MINOR. THERE ARE NO OUTLIERS...AND ONE
COULD RECOMMEND A BLEND OF THE OPERATIONAL MODELS. WE HAVE A
SLIGHT PREFERENCE TOWARD THE ECMWF AND ECMWF ENSEMBLE MEAN...WHICH
MAINTAIN A CLOSED LOW FOR LONGER DURATION AND DRIFTING AT A
SLIGHTLY SLOWER PACE. THIS WOULD SEEM FAVORED BY ITS POSITION
WITHIN A LARGER SCALE SHORTWAVE RIDGE.

www.wpc.ncep.noaa.gov/html/model2.shtml...
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

BURKE