Prognostic Meteorological Discussion
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000
FXUS10 KWNH 300419
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1218 AM EDT THU OCT 30 2014

VALID OCT 30/0000 UTC THRU NOV 02/1200 UTC

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


00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


AMPLIFIED TROUGH/CLOSED LOW MOVING INTO THE WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF COMPROMISE
CONFIDENCE: ABOVE AVERAGE

ON THE WHOLE, THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS SYSTEM.
DETAIL ISSUES PERSIST WITHIN ITS NORTHERN PORTION NEAR MT AND
SOUTHERN PORTION NEAR CA, WHICH IS ALSO REFLECTED WITH THE 12Z
ECMWF/18Z GEFS MEANS.  A COMPROMISE OF THE 00Z GFS/12Z ECMWF, WITH
A SLIGHTLY GREATER LEAN TOWARDS THE GFS WHICH HAS SHOWN BETTER
CONTINUITY, SHOULD ACCOUNT FOR THESE ISSUES.


TROUGH AMPLIFYING ACROSS EASTERN NORTH AMERICA
CLOSED LOW SWINGING THROUGH THE CAROLINAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/GFS/CANADIAN COMPROMISE
CONFIDENCE: BELOW AVERAGE

THIS TROUGH AMPLIFIES DUE TO UPSTREAM AMPLIFICATION OF A
TROUGH/RIDGE COUPLET NEAR THE WEST COAST/GREAT PLAINS
RESPECTIVELY.  THE 12Z ECMWF/12Z GFS SHOW 500 HPA HEIGHT ANOMALIES
~5 SIGMAS BELOW AVERAGE FOR EARLY NOVEMBER, CLOSE TO A ONCE IN A
50 YEAR OR HISTORIC EVENT PER THE GRUMM/HART WORK FROM 2002.  THE
BETTER ST. LOUIS UNIVERSITY CIPS ANALOGS FOR THIS EVENT (BASED ON
THE 12Z GFS) ARE FROM OCT 26 1990 (BONNER BRIDGE STORM), DEC 4
1987, NOV 6 2010 -- THESE THREE MATCHED WELL THIS TIME YESTERDAY
-- ALONG WITH OCT 28 2008, DEC 5 1981, OCT 18 2009, NOV 11 1987
(VETERAN`S DAY SNOWSTORM), AND NOV 23 2002.  THE 00Z NAM REMAINED
DEEPER AND ON THE SOUTHWEST SIDE OF THE GUIDANCE BY SATURDAY
EVENING -- ITS USUAL BIAS.  A COMPROMISE OF THE 12Z ECMWF/12Z
CANADIAN/00Z GFS FITS THE 12Z ECMWF/18Z GEFS MEANS AND 12Z GLOBAL
ENSEMBLE LOW CLUSTERING THE BEST.  CONSIDERING THE EXTREME NATURE
OF THE EVENT EXPECTED, CONFIDENCE IS BELOW AVERAGE.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ROTH
$$





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