Prognostic Meteorological Discussion
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000
FXUS10 KWNH 100425
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1223 AM EDT THU JUL 10 2014

VALID JUL 10/0000 UTC THRU JUL 13/1200 UTC

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

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


UPPER LOW MOVING NORTHWARD OFFSHORE CA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/UKMET COMPROMISE
CONFIDENCE: AVERAGE

THE 00Z GFS/00Z NAM ARE ON THE FAST SIDE OF THE GUIDANCE WITH THIS
SYSTEM WHILE THE 12Z CANADIAN IS THE SLOWEST -- ITS USUAL BIAS.
WITH THE SYSTEM EMBEDDED WITHIN INCREASINGLY SOUTHERLY FLOW,
BELIEVE THE CANADIAN IS TOO SWIFT.  THE GFS CAN HAVE A FAST BIAS
WITH SYSTEMS IN THE WESTERLIES, SO IT MIGHT BE TOO QUICK HERE.
THE PREFERENCE IS FOR A 12Z ECMWF/12Z UKMET COMPROMISE WITH
AVERAGE CONFIDENCE CONSIDERING THE SPREAD SEEN IN THE GUIDANCE.


DEEP CYCLONE MOVING ACROSS SOUTH-CENTRAL CANADA
ITS TRAILING COLD FRONT MOVING THROUGH THE GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CANADIAN/ECMWF/UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

BOTH THE 00Z GFS AND 00Z NAM MOVE THE SURFACE AND 700 HPA PORTIONS
OF THE FRONT QUICKER TO THE EAST THROUGH THE GREAT LAKES DUE TO
GRIDSCALE FEEDBACK WHICH IS DISTORTING THEIR LOW-LEVEL MASS FIELDS
TOWARDS A QUICKER PROGRESSION.  THE PREFERENCE IS FOR A COMPROMISE
OF THE 12Z CANADIAN/12Z ECMWF/12Z UKMET WITH ABOVE AVERAGE
CONSIDERING THE CONVECTIVE FEEDBACK SEEN IN THE GFS AND NAM.


DEEP CYCLONE MOVING THROUGH EASTERN CANADA
FRONT SLIPPING INTO THE SOUTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE IS IN GOOD AGREEMENT WITH THE DETAILS OF THIS
FEATURE.  TO DEAL WITH ANY LINGERING DETAIL ISSUES, A GENERAL
MODEL COMPROMISE IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE DUE TO
THE MINIMAL SPREAD IN THE GUIDANCE.


...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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