Prognostic Meteorological Discussion
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000
FXUS10 KWNH 280415
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1114 PM EST THU NOV 27 2014

VALID NOV 28/0000 UTC THRU DEC 01/1200 UTC

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


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


SHORTWAVE MOVING TOWARDS THE PACIFIC NW SUN/MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 12Z UKMET IS MORE AGGRESSIVE IS FLATTENING THE TOP OF THE
SOUTHWESTERN RIDGE THAN THE OTHER GUIDANCE -- A BIAS SOMETIMES
SEEN IN THE DETERMINISTIC GUIDANCE.  WITH THE SUPPORT OF THE 18Z
GEFS/12Z ECMWF ENSEMBLE MEAN SOLUTIONS, PREFER A COMPROMISE OF THE
12Z CANADIAN/12Z ECMWF/00Z NAM/00Z GFS SOLUTIONS HERE WITH ABOVE
AVERAGE CONFIDENCE.


SHORTWAVE APPROACHING CALIFORNIA SAT NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF/UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM BECOMES TOO STRONG WITH THIS SYSTEM -- ITS USUAL BIAS.
 THE 12Z CANADIAN IS THE WEAKEST, WEAKER THAN BOTH THE 12Z
ECMWF/18Z GEFS ENSEMBLE MEANS.  A COMPROMISE OF THE 00Z GFS/12Z
UKMET/12Z ECMWF IS PREFERRED WITH THIS SYSTEM WITH ABOVE AVERAGE
CONFIDENCE.


SHORTWAVE MOVING THROUGH THE NORTHWEST/NRN PLAINS
FRONT MOVING THROUGH NEW ENGLAND LATE SUN/EARLY MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/GFS/UKMET COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WITH THE MAIN TROUGH AXIS, THE 12Z CANADIAN/12Z UKMET LAG THE
OTHER GUIDANCE FROM LATE SATURDAY INTO SUNDAY BEFORE CATCHING UP
TO THE CONSENSUS.  A SHORTWAVE MOVING AROUND ITS EASTERN SIDE
LEADS TO TIMING ISSUES WITH A COLD FRONT MOVING INTO THE
NORTHEAST, WITH THE 00Z GFS/18Z GEFS MEAN THE QUICKEST (THEIR
USUAL BIAS) AND THE 12Z CANADIAN/12Z ECMWF THE SLOWEST (A BIAS
SEEN IN THE CANADIAN AND OCCASIONALLY IN THE ECMWF).  IN GENERAL,
A COMPROMISE BETWEEN THE 12Z ECMWF/00Z GFS APPEARS BEST, WHICH IN
NEW ENGLAND, IS CLOSEST TO THE 12Z UKMET IN REGARDS TO FRONTAL
TIMING.  CONFIDENCE IS SLIGHTLY ABOVE AVERAGE IN THIS PREFERENCE.


UPPER TROUGH MOVING THROUGH NORTHERN MEXICO/TX
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE SHORTWAVE MOVING
THROUGH NORTHERN MEXICO INTO TEXAS.


...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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