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000
FXUS10 KWNH 191851
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 PM EDT WED JUN 19 2013

VALID JUN 19/1200 UTC THRU JUN 23/0000 UTC

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

FINAL 12Z MODEL EVALUATION INCLUDING THE UKMET...CANADIAN AND
EUROPEAN

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

PREFERENCE: BLEND OF THE 12Z ECMWF/GFS AND OLD ECMWF ENSEMBLE MEAN
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

IN TERMS OF RUN TO RUN CONSISTENCY...BOTH THE 12Z NAM AND THE GFS
WERE FAIRLY CLOSE TO THEIR PREVIOUS RUNS IN TERMS OF PLACEMENT OF
THE CENTER OF THE LOW...ALTHOUGH THE GFS HAD LESS AMPLITUDE OF THE
DOWNSTREAM RIDGING BY 22/00Z WHICH ALLOWED THE MID LEVEL LOW TO BE
MORE OBLONG THAN IN THE PREVIOUS RUN. THE UKMET BECAME SLOWER
MODELS TO OPEN WHEN COMPARED TO OTHER GUIDANCE BY 22/00Z. THE
ECMWF WAS BEST CLUSTERED WITH THE GFS AND ITS PREVIOUS MEAN SO SAW
LITTLE REASON TO CHANGE THE RECOMMENDATION.

...500 MB WAVE MOVING FROM THE CENTRAL PLAINS/UPPER MS VALLEY TO
OH VALLEY LATE DAY 1 THROUGH DAY 2...

PREFERENCE:  NON-UKMET/CANADIAN MODEL COMPROMISE
CONFIDENCE:  AVERAGE

MODELS STILL DEPICT 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. EVENTUALLY THE
WAVE RIDES OVER THE TOP OF THE BUILDING CENTRAL RIDGE ON DAY 2 AND
CONTINUES INTO THE OH VALLEY.  THE CANADIAN/UKMET/ECMWF ALL SHOW
RUN TO RUN DIFFERENCES WITH THIS FEATURE BUT LITTLE TO CALL A
TREND.  SO WE WILL CONTINUE TO RECOMMEND A 12Z GFS/NAM/ECMWF AND
19/00Z ECMWF MEAN.

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

PREFERENCE: COMPROMISE OF 12Z GFS/ECMWF...18/21Z SREF OR 19/00Z
ECMWF
CONFIDENCE: 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.  OVER THE MID ATLANTIC
AND SOUTHEAST...THE MODEL MAJORITY OF MODELS STILL SHOW AN
ELONGATED 850-500 MB CYCLONIC SHEAR ZONE WITH EMBEDDED WEAK
CIRCULATIONS SFC/ALOFT FRI-FRI NIGHT.

MINOR TIMING/INTENSITY DIFFERENCES EXIST WHICH 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...

BANN

$$