MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
255 PM EDT TUE JUN 18 2013

VALID JUN 18/1200 UTC THRU JUN 22/0000 UTC

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

FINAL 12Z MODEL EVALUATION...INCLUDING THE UKMET/CANADIAN/ECMWF

...BROAD UPPER LEVEL TROUGHING OVER THE GREAT LAKES AND
NORTHEAST...
 
PREFERENCE: NON NAM COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE 

THE MOST RECENT GUIDANCE SHOWS DECENT AGREEMENT WITH BROAD UPPER
LEVEL TROUGHING AND A CLOSED CENTER TRACKING FROM QUEBEC INTO THE
CANADIAN MARITIMES BY WED MORNING.  SEVERAL SHORTWAVES EMBEDDED
WITHIN THE FAST FLOW ARE NOT BEING HANDLED PARTICULARLY
WELL...LEADING TO SOME TIMING DIFFERENCES BETWEEN THE SUITE OF
MODELS AS WELL AS SOME RUN TO RUN DIFFERENCES.  THE ECMWF HAD BEEN
A SHARP/FAST OUTLIER WHEN COMPARED WITH THE 12Z NCEP GUIDANCE. 
THE 18/12Z ECMWF MADE SOME ADJUSTMENTS TOWARDS A SLOWER AND LESS
AMPLIFIED SOLN...BECOMING MORE USUABLE THAT BEFORE. 
LIKEWISE...THE CANADIAN MADE SIMILAR ADJUSTMENTS WHILE THE UKMET
HAD GOOD RUN TO RUN CONSISTENCY.  THIS LEAVES MOST MODELS
MODELS...SAVE FOR THE NAM...CLUSTERED AROUND THE PREVIOUS ENSEMBLE
MEANS.

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

PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE NAM REMAINED ON THE SLOWEST SIDE OF THE GUIDANCE AND EVEN
SHOWED SOME RUN TO RUN SLOWING WHEN COMPARED WITH OTHER 12Z
MODELS.  THE 12Z ECMWF WAS ALSO SLOWER WITH ITS EASTWARD MOVEMENT
WHILE THE CENTER IS NOW SAGGING SOUTH ACROSS WA/OR.  THIS PUTS IT
IN BETTER AGREEMENT WITH THE CANADIAN/GFS AND THE PREVIOUS
ENSEMBLE MEANS.  GIVEN THAT SUPPORT...WILL CONTINUE TO PUT MOST
WEIGHT ON THE GFS AND ECMWF.

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

PREFERENCE:  GENERAL MODEL COMPROMISE
CONFIDENCE:  BELOW 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 TWO AND
OHIO VALLEY ON DAY 3...WITH LITTLE COHERENCE IN RUN TO RUN
DIFFERENCES IN TERMS OF AMPLITUDE AND TO A LESSER EXTENT THE
FORWARD SPEED.  THE GFS NOW SHOWING MORE AMPLITUDE THAN THE NAM. 
OTHER GLOBAL MODELS SHOWED SIMILAR RUN TO RUN DIFFERENCES WITH
LITTLE IN THE WAY OF A CLEAR TREND.  WILL RECOMMEND A GENERAL
COMPROMISE. 

...MODEL TREND GRAPHICS AT www.wpc.ncep.noaa.gov/html/model2.shtml

BANN