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000
FXUS10 KWNH 200633
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 AM EDT MON MAY 20 2013

VALID MAY 20/0000 UTC THRU MAY 23/1200 UTC

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


00Z MODEL EVALUATION WITH MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM INITIALIZATION ERRORS WHICH APPEAR IMPORTANT TO THE FORECAST
ARE LISTED WITHIN THE RESPECTIVE SECTION BELOW.  ANY GFS
INITIALIZATION ERRORS DO NOT APPEAR TO DEGRADE ITS SHORT RANGE
FORECAST.


DEEP CYCLONE MOVING INTO THE PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  NON-NAM/NON-SREF MEAN COMPROMISE
CONFIDENCE:  ABOVE AVERAGE

OTHER THAN THE SLOW AND DEEP 00Z NAM/21Z SREF MEAN, THE REMAINDER
OF THE GUIDANCE IS IN GOOD AGREEMENT CONCERNING THIS SYSTEM`S
EVOLUTION.  THE AFOREMENTIONED PIECES OF GUIDANCE ARE LIKELY SLOW
DUE TO THE WRF PHYSICS THEY INCLUDE, AND IN THE CASE OF THE NAM,
THIS IS A WELL-KNOWN BIAS THAT HAS EXISTED FOR SEVERAL YEARS.
WITH THE 18Z GEFS MEAN CLOSER TO THE QUICKER/MORE EASTWARD 12Z
ECMWF ENSEMBLE MEAN SOLUTION, THE NON-NAM/NON-SREF MEAN EASTERN
CONSENSUS IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE DUE TO ITS
INCREASINGLY AMPLIFIED AND SLOW-MOVING NATURE.


SYSTEM MOVING THROUGH THE GREAT LAKES/NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  03Z RAP USEFUL THIS MORNING IN WISCONSIN
             GENERAL MODEL COMPROMISE ELSEWHERE
CONFIDENCE:  AVERAGE

THROUGH THIS AFTERNOON, THE 03Z RAP APPEARS TO BE CAPTURING THE
LOWER DEW POINTS AT THE 850 HPA LEVEL, WHEREAS THE 00Z NAM/12Z
ECMWF HAVE NOT.  THIS NEGATIVELY IMPACTS THE FORECAST OF THE CAPE
CONVECTIVE INDEX THROUGH AT LEAST 15Z MONDAY.  THE LA CROSSE
WISCONSIN WEATHER FORECAST OFFICE NOTICED THIS ISSUE WITHIN THE
GUIDANCE AND RELAYED IT TO US VIA THE INTERNAL 12 PLANET CHAT
UTILITY, WHICH APPEARS TO BE IMPORTANT FOR THE MORNING FORECAST
ACROSS PORTIONS OF WISCONSIN.  THIS LED TO A PREFERENCE FOR THE
03Z RAP ACROSS WISCONSIN

THERE IS VERY GOOD AGREEMENT AMONGST THE GUIDANCE WITH THIS
SYSTEM, AS THE ECMWF MADE A BIG NORTHWARD ADJUSTMENT WITH THE WARM
FRONT PROGRESSION ACROSS THE NORTHEAST AND SOME OF THE 00Z
GUIDANCE SHIFTED SOUTHWARD WITH THE SECONDARY COLD FRONT/POSSIBLE
PNEUMONIA FRONT DROPPING OUT OF LAKE MICHIGAN INTO ILLINOIS AND
INDIANA.  CONSIDERING THE ABOVE, A GENERAL MODEL COMPROMISE IS
PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING THE SYSTEM`S
PROGRESSIVE NATURE.


SHORTWAVE TROUGH MOVING THROUGH CAROLINAS
WEAK UPPER LEVEL LOW/TROUGH STUCK ACROSS FLORIDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  12Z ECMWF/00Z GFS COMPROMISE
CONFIDENCE:  ABOVE AVERAGE

THE 00Z NAM IS SLOW WITH ITS SHORTWAVE PROGRESSION ACROSS THE
CAROLINAS -- WHICH HAS BEEN ITS HISTORY WITH THIS SYSTEM.  ACROSS
FLORIDA, THE ECMWF HAS TRENDED STRONGER WITH THE LINGERING UPPER
LOW/TROUGH SINCE THIS TIME YESTERDAY, IN THE DIRECTION OF THE MORE
CONSISTENT GFS.  THE 00Z CANADIAN/00Z UKMET SHOW A WEAKER SYSTEM,
THOUGH THERE HAS BEEN A NOTICEABLE TREND TOWARDS A STRONGER SYSTEM
OVER THEIR PAST 36 HOURS OF RUNS.  THE ECMWF TENDS TO HAVE A WEAK
BIAS WITH WEAK ENERGY IN THE SUBTROPICS, SO A STRONGER SOLUTION IS
LIKELY TO MATERIALIZE. A 00Z ECMWF/00Z GFS COMPROMISE IS PREFERRED
OVERALL, WITH CONFIDENCE ABOVE AVERAGE IN THIS CHOICE DUE TO THE
OVERALL SYSTEM`S SLOW PROGRESSION.


...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
$$