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Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1646Z Sep 28, 2014)
 
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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
1246 PM EDT SUN SEP 28 2014

VALID SEP 28/1200 UTC THRU OCT 02/0000 UTC

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

12Z NAM/GFS EVALUATION...INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


WEAK CLOSED LOW/TROUGH MOVING FROM THE MIDWEST TO THE MID-ATLANTIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

ONLY MINOR MODEL DIFFERENCES REMAIN WITH THIS FEATURE SO A GENERAL
MODEL COMPROMISE IS RECOMMENDED TO SMOOTH OUT ANY OF THE SHORT
TERM DIFFERENCES.


SHORTWAVE TROUGH REACHING THE UPPER GREAT LAKES ON MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND THE 00Z ECMWF
CONFIDENCE: AVERAGE

A SIGNIFICANT TREND HAS BEEN SEEN IN THE GUIDANCE TO BE MORE
AMPLIFIED WITH THIS WAVE...MORE LIKE THE ECMWF AS THE UPPER WAVE
CROSSES THE GREAT LAKES. THE ECMWF/UKMET/CMC ARE SLIGHTLY MORE
AMPLIFIED/SOUTH WITH THE SHORTWAVE AS IT NEARS THE EAST COAST WED
MORNING...WITH THE NAM/GFS SLIGHTLY WEAKER/NORTH. THE ENSEMBLE
MEANS ARE ALSO NOW IN PRETTY GOOD AGREEMENT SO GIVEN THE GOOD
MODEL AGREEMENT ON TIMING AND REASONABLE AGREEMENT ON STRENGTH...A
BLEND OF THE TWO CAMPS APPEARS WARRANTED. THIS IS BEST REPRESENTED
BY AVERAGING THE 12Z GFS AND 00Z ECMWF.


BROAD UPPER TROUGH/EMBEDDED VORTS OVER THE SOUTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: BELOW AVERAGE

ALL OF THE MODELS HAVE TRENDED MORE SUPPRESSED SINCE RUNS FROM
12Z/27 WITH A WEAK LOW FORECAST TO TRACK ACROSS THE SOUTHEAST
TONIGHT INTO MONDAY AND CONTINUE TO SHOW INCONSISTENCIES ON
TIMING...BUT ALSO A TREND TO BE FASTER WITH THE WAVE. THE 00Z
ECMWF AND 00Z EC MEAN ARE WEAKEST WITH THE 850-700 MB WAVE...BUT
THE NAM/GFS/UKMET/CMC ALL SEEM TO SHOW SOME SIGNS OF CONVECTIVE
FEEDBACK. THE ENSEMBLE MEANS SUPPORT THEIR DETERMINISTIC
COUNTERPARTS.

IT APPEARS THE NAM/SREF ARE TOO SLOW/STRONG GIVEN THE REMAINING
MODELS AND TRENDS...BUT THE 00Z UKMET/CMC APPEAR A BIT TOO FAST 
JUST CONSIDERING MASS FIELDS...THE GFS/ECMWF SEEM MOST
USEFUL...THE GFS LIKELY TOO STRONG BUT THE ECMWF POSSIBLY TOO WEAK
WITH BOTH SHOWING A FAVORABLE TIMING. CONFIDENCE REMAINS
LIMITED...AND HI-RES MODEL QPF MAY OFFER A MORE REASONABLE
DEPICTION. PLEASE SEE WPC QPF TEXT DISCUSSION PRODUCTS FOR DETAILS
ON RAINFALL AMOUNTS.


DEEP TROUGH/CLOSED LOW MOVING FROM THE WEST INTO THE N-CNTRL U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z ECMWF/CMC AND 12Z NAM
CONFIDENCE: AVERAGE

THE MODELS ARE IN DECENT AGREEMENT HERE BUT THERE ARE DIFFERENCES
WORTH NOTING...FIRST WITH THE 12Z GFS BEING A BIT STRONGER THAN
THE REMAINING MODEL CONSENSUS...AND PROBABLY TOO STRONG. REGARDING
TIMING...THE ENSEMBLE MEANS SUPPORT SOMETHING CLOSE TO THE
NAM/ECMWF/CMC WITH THE ECMWF LIKELY HOLDING THE BEST MIDDLE GROUND
AND CONTINUITY OF THE THREE MODELS.


MID-UPPER TROUGH REACHING THE PACIFIC NORTHWEST MON NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: AVERAGE

THE GFS/ECMWF CONTINUE TO REPRESENT A FAVORABLE MIDDLE GROUND IN
THE AMPLITUDE/TIMING OF THIS SHORTWAVE AS IT REACHES THE CONUS BY
MID WEEK WITH SUPPORT FROM THE ENSEMBLE MEANS.


www.wpc.ncep.noaa.gov/html/model2.shtml...
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

OTTO