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Model Diagnostics Discussion
 
(Latest Discussion - Issued 0452Z Jan 28, 2015)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1151 PM EST TUE JAN 27 2015

VALID JAN 28/0000 UTC THRU JAN 31/1200 UTC

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

00Z NAM/GFS EVALUATION...INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


DEPARTING NEW ENGLAND COASTAL STORM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM INITIALIZED THE SURFACE LOW LOCATED BETWEEN CAPE COD
AND NOVA SCOTIA AT 00Z/28 6 MB TOO DEEP BUT THE 00Z GFS ANALYSIS
WAS ONLY 1 MB TOO WEAK. 12 HR FORECASTS FROM THE 12Z
ECMWF/UKMET/CMC WERE TOO DEEP WITH THE LOW...BY AS MUCH AS 12 MB.

REGARDING POSITION...THE LATEST DETERMINISTIC/ENSEMBLE MEAN
GUIDANCE SHOWS VERY GOOD AGREEMENT EXCEPT FOR THE 12Z CMC WHICH IS
QUICKER TO DEPART THE LOW EARLY WED MORNING. GIVEN IMPACTS TIED TO
THE STORM ARE QUICKLY FADING...AND THE 00Z GFS AGREES BEST ON
STRENGTH/POSITION...A SIMPLE 00Z GFS SOLUTION WILL BE
PREFERRED...BUT OTHER MODELS CERTAINLY HAVE UTILITY HERE.


MID-LEVEL SHORTWAVE REACHING THE CENTRAL PLAINS LATE WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE LATEST MODELS SHOW SUFFICIENT AGREEMENT HERE TO SUPPORT A
GENERAL MODEL COMPROMISE FOR THE PREFERENCE. ALTHOUGH THERE HAS
BEEN SOME RUN TO RUN VARIABILITY IN TIMING...THESE DIFFERENCES ARE
MINOR AND WITHIN THE NOISE OF EXPECTED RUN TO RUN CHANGES.


MID-LEVEL SHORTWAVE REACHING THE N-CNTRL U.S. LATE WED
EVOLVING NEGATIVELY TILTED UPPER TROUGH ACROSS THE NORTHEAST BY
  FRI AND COASTAL NEW ENGLAND SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 21Z SREF MEAN OR 00Z GFS/12Z UKMET BLEND THROUGH 12Z/30
    21Z SREF FROM 12Z/30-12Z/31
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THERE IS DECENT MODEL AGREEMENT FROM THE SURFACE THROUGH THE
MID-LEVELS WITH THIS SYSTEM THROUGH DAY 2...12Z/30. BEYOND
12Z/30...SPREAD INCREASES REGARDING THE POSITION OF A NEGATIVELY
TILTED MID-LEVEL TROUGH OFF OF THE NORTHEAST COAST AND POSSIBLE
CLOSED LOW DEVELOPMENT. THIS IMPACTS WHERE A SURFACE LOW WILL
DEVELOP WITH THE ENSEMBLE SCATTER LOW PLOTS SHOWING A WIDE RANGE
OF POSSIBILITIES BY 12Z/31...BUT FEEL THE 00Z GFS AND 12Z UKMET
GET TOO CLOSE TO DOWNEAST MAINE GIVEN THEY LIE ON THE WESTERN EDGE
OF THE ENSEMBLES. THE ENSEMBLE MEANS...BEST REPRESENTED BY THE 21Z
SREF MEAN...SHOW A POSITION A BIT FARTHER EAST THAN THE GFS/UKMET.
THE 12Z ECMWF APPEARS TO BE LOCATED FARTHER OFFSHORE WITH THE
CLOSED LOW BY 12Z/31 COMPARED TO A CONSENSUS OF THE REMAINING
DETERMINISTIC / ENSEMBLE GUIDANCE.


CLOSED LOW ACROSS THE SOUTHWEST BY THE END OF THE WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

THERE IS RELATIVELY MINOR SPREAD IN A SOMEWHAT BROAD UPPER TROUGH
MAKING ITS WAY TOWARD THE WEST COAST. BY FRIDAY...THE MODELS
DEPICT A LARGE UPPER LOW WITH A BIT OF A N/S ELONGATION STRETCHING
FROM THE GREAT BASIN SOUTH INTO THE NORTHERN BAJA PENINSULA.
STRONGER MODEL CLUSTERING OVERALL TENDS TO FAVOR A BLEND OF THE
00Z GFS AND 12Z ECMWF...AND THAT WILL BE THE PREFERENCE.


www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

OTTO