Prognostic Meteorological Discussion
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000
FXUS10 KWNH 221620
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1119 AM EST SAT NOV 22 2014

VALID NOV 22/1200 UTC THRU NOV 26/0000 UTC

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

12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


SHORTWAVE SPURRING LOW PRESSURE IN THE DAKOTAS TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: UKMET/CANADIAN/NAM COMPROMISE
CONFIDENCE: AVERAGE

DIFFERENCES WITH SHORTWAVE STRENGTH ALOFT LEAD TO SIGNIFICANT
SURFACE PRESSURE ISSUES WITH A LOW PRESSURE SYSTEM MOVING INTO THE
DAKOTAS TUESDAY, WITH THE 12Z GFS THE WEAKEST AND THE 00Z ECMWF
THE STRONGEST.  A SOLUTION ON THE WEAKER SIDE OF THE GUIDANCE
MAKES SENSE GIVEN THE QUICK AND NON-AMPLIFIED FLOW PATTERN IN THAT
AREA.  HOWEVER, THE 00Z UKMET/00Z CANADIAN/12Z NAM ARE CLOSEST TO
THE INTERMEDIATE 00Z ECMWF/06Z GEFS/09Z SREF MEAN SOLUTIONS, AND
ARE PREFERRED WITH AVERAGE CONFIDENCE CONSIDERING THE SYSTEM`S
QUICK MOVEMENT THROUGH THE FLOW PATTERN.


CONSOLIDATED MIDWESTERN TROUGH
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS/NON-GEFS COMPROMISE
CONFIDENCE: ABOVE AVERAGE

MUCH LIKE OVERNIGHT, CONVECTIVE/GRIDSCALE FEEDBACK HAUNTS THE
06Z/12Z GFS SOLUTIONS (AND LIKELY THE 06Z GEFS MEAN DUE TO SIMILAR
PHYSICS) WHICH USE MULTIPLE HUGE VERTICAL MOTION BULL`S EYES
ASSOCIATED WITH AN APPARENT SQUALL LINE AND CONVECTION IN THE
MIDWEST TO OVER-DEEPEN THE SURFACE LOW MOVING FROM THE
MID-MISSISSIPPI VALLEY THROUGH THE GREAT LAKES.  THIS SUBSEQUENTLY
CAUSES THE GFS/GEFS MEAN COLD FRONTS TO WHIP EASTWARD FASTER THAN
THE REMAINDER OF THE GUIDANCE.  THE PREFERENCE IS FOR A 12Z
NAM/09Z SREF MEAN/00Z CANADIAN/00Z UKMET/00Z ECMWF COMPROMISE FOR
THE ENTIRE SYSTEM WITH ABOVE AVERAGE CONFIDENCE.


...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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