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000
FXUS10 KWNH 190450
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1249 AM EDT WED JUN 19 2013

VALID JUN 19/0000 UTC THRU JUN 22/1200 UTC

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

INITIAL 00Z MODEL EVALUATION...INCLUDING THE NAM/GFS AND
PRELIMINARY PREFERENCES


...DEEP CLOSED LOW MOVING ACROSS THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES...

PREFERENCE: BLEND OF THE 12Z ECMWF/ECMWF ENSEMBLE MEAN/00Z GFS/12Z
CANADIAN GLOBAL
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z NAM/21Z SREF MEAN CONTINUED TO BE FASTER IN BODILY MOVING
THE CLOSED 500 MB LOW INTO SOUTHWEST CANADA WHILE THE 12Z
ECMWF/18-00Z GFS/12Z ECMWF ENSEMBLE MEAN/12Z CANADIAN GLOBAL SHOW
THE 500 MB LOW PERSISTING IN ID/WESTERN MT...WHILE ALLOWING A
PIECE OF THE LOW AND 700 MB WAVE TO EJECT NORTHEAST.  THE 12Z
UKMET WAS AN OUTLIER IN INTENSIFYING THIS EJECTING SHORTWAVE...AND
MAINTAINS A SECOND CLOSED LOW NEAR THE WA/ID BORDER WITH BRITISH
COLUMBIA ON THE NORTHWEST EDGE OF THE GUIDANCE SUITE..SO THE 12Z
UKMET HAS THE LOWEST PROBABILITY OF THE VARIOUS SOLUTIONS.
THE 12Z ECMWF ECMWF ENSEMBLE MEAN 500 MB LOW IS CLOSE TO THE 00Z
GFS SOLUTION FRI NIGHT.
THE CLUSTERING OF THE 12Z ECMWF/00Z GFS WITH THE CANADIAN
GLOBAL/12Z ECMWF ENSEMBLE MEAN SUGGESTS A CONSENSUS OF THESE
SOLUTIONS BE USED.

...500 MB WAVE MOVING FROM THE CENTRAL PLAINS-UPPER MS VALLEY ON
DAY TWO AND OHIO VALLEY DAY THREE...

PREFERENCE:  NON-UKMET MODEL COMPROMISE
CONFIDENCE:  AVERAGE

THE MODELS STILL SHOW A LOW AMPLITUDE 500 MB WAVE MOVING EAST IN
CONFLUENT FLOW FROM THE CENTRAL PLAINS TO MS VALLEY ON DAY ONE AND
WEAKENING AS IT CROSSES THE OHIO VALLEY ON DAY 2.  THE 12Z UKMET
IS LOWEST IN AMPLITUDE WITH THIS WAVE WITH BETTER CLUSTERING AMONG
THE GFS/18Z GEFS MEAN/12Z ECMWF/ECMWF ENSEMBLE MEAN/NAM.
EVENTUALLY THIS WAVE ROUNDS THE TOP OF THE BUILDING CENTRAL US
RIDGE ON DAY 2 AND MOVES INTO THE OHIO VALLEY.  RISING HEIGHTS AND
WAVE DEAMPLIFICATION IN THE SUITE OF SOLUTIONS SHOWS AGREEMENT ON
DISSIPATION AS THE HEIGHTS INCREASE AND MID LEVEL RIDGE INCREASES
IN INTENSITY FRI NIGHT ACROSS THE REGION.  THE OVERALL TREND
AGREEMENT AMONG THE MODELS/ENSEMBLE MEANS SUGGESTS A CONSENSUS BE
USED.


...BROAD UPPER LEVEL TROUGHING OVER THE GREAT LAKES AND
NORTHEAST...
...TRAILING SHORTWAVE ENERGY OVER THE SOUTHEAST COASTAL AREAS
FRI-FRI NIGHT...

PREFERENCE: 00Z GFS/12Z ECMWF/21Z SREF MEAN COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MOST RECENT GUIDANCE SHOWS DECENT AGREEMENT WITH BROAD UPPER
LEVEL TROUGHING
ACROSS THE NORTHEAST AND LAKES DAYS 1-2 BEFORE RISING HEIGHTS AS
THE BUILDING CENTRAL US RIDGE DRIFTS EAST.  THE ECMWF/UKMET
MAINTAIN A TROUGH LONGER WHILE THE NAM/GFS/21Z SREF MEAN DEAMPLIFY
THE TROUGH SOONER.  GIVEN CONFLICTING RESOLUTION...PREFER TO TAKE
A BLEND UNTIL IT BECOMES CLEARER WHICH CAMP WILL BE MORE CORRECT.

OVER THE MID ATLANTIC AND SOUTHEAST...THE MODEL MAJORITY SHOWS AN
ELONGATED 850-500 MB CYCLONIC SHEAR ZONE WITH EMBEDDED WEAK
CIRCULATIONS SFC/ALOFT FRI-FRI NIGHT.
A STALLED SFC FRONT SITS JUST OFF THE COAST OF THE CAROLINAS/GA
WITH WEAK WAVES EMBEDDED WITHIN THE BOUNDARY. MINOR
TIMING/INTENSITY DIFFERENCES SUGGESTS A MULTI-MODEL/SREF ENSEMBLE
MEAN CONSENSUS BE USED TO RESOLVE DIFFERENCES.


...MODEL TREND GRAPHICS AT
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

PETERSEN

$$