Prognostic Meteorological Discussion
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000
FXUS10 KWNH 221842
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
141 PM 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 MODEL EVALUATION WITH 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 12Z 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 12Z UKMET/12Z CANADIAN/12Z NAM ARE SOMEWHAT
STRONGER THAN THE INTERMEDIATE 00Z ECMWF/12Z 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 12Z
GFS OPERATIONAL AND PARALLEL 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 (INTO THE
MID TO UPPER 960S HPA).  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/12Z CANADIAN/12Z
UKMET/12Z ECMWF COMPROMISE FOR THE ENTIRE SYSTEM WITH ABOVE
AVERAGE CONFIDENCE.  WITH THIS PREFERENCE, RECORD LOW SEA LEVEL
PRESSURE VALUES FOR NOVEMBER ARE POSSIBLE IN LOCATIONS SUCH AS
GRAND RAPIDS AND SAULT SAINTE MARIE MI SUNDAY NIGHT INTO MONDAY
MORNING.


...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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