Prognostic Meteorological Discussion
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000
FXUS10 KWNH 170635
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
234 AM EDT FRI APR 17 2015

VALID APR 17/0000 UTC THRU APR 20/1200 UTC

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

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


UPPER LOW CLOSING OFF IN NORTHERN MN EARLY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z NAM IS THE MOST AMPLIFIED WITH THIS SYSTEM BY MONDAY
MORNING -- ITS USUAL BIAS -- WHILE THE 00Z UKMET IS THE SLOWEST.
THE 00Z CANADIAN LAGS THE GFS/ECMWF AND THEIR ENSEMBLE MEAN
SOLUTIONS.  A SLIGHTLY WEAKENING UPSTREAM RIDGE SHOULD ENSURE SOME
SLOW PROGRESSION, SO BELIEVE THE UKMET/CANADIAN ARE TOO SLOW.  A
COMPROMISE OF THE 00Z GFS/00Z ECMWF IS PREFERRED WITH SLIGHTLY
ABOVE AVERAGE CONFIDENCE.


SOUTHERN STREAM CYCLONE MOVING INTO THE GREAT LAKES MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z UKMET SLOW EVOLUTION OF THE NORTHERN STREAM TROUGH HAS LED
TO ITS SOLUTION WITH THIS SYSTEM TO BE SLOW TO PROGRESS NORTHEAST
AS WELL -- IT LIES AT THE SOUTHERNMOST FRINGE OF THE 12Z GLOBAL
ENSEMBLE LOW SPREAD.  A NON-UKMET COMPROMISE IS ADVISED WITH ABOVE
AVERAGE CONFIDENCE.



ENERGY ALOFT DROPPING DOWN THE CA COAST SAT/SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE SHOWS REASONABLY GOOD AGREEMENT WITH THIS SYSTEM.



SHORTWAVE CROSSING NEW ENGLAND SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CANADIAN/UKMET/ECMWF COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z GFS CLOSES THIS SYSTEM OFF AT 500 HPA AS IT CROSSES MAINE,
AND THE 00Z NAM IS THE SLOWEST -- A TYPICAL NAM BIAS.  CONSIDERING
THE BREADTH AND NON-AMPLIFIED UPSTREAM RIDGE, BELIEVE THE GFS IS
TOO STRONG HERE.  A NON-GFS COMPROMISE IS PREFERRED 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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