MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 PM EDT FRI MAY 24 2013

VALID MAY 24/1200 UTC THRU MAY 28/0000 UTC

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

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

NO SIGNIFICANT INITIALIZATION ERRORS ARE SEEING IMPACTING THE
SHORT RANGE FORECAST.

...DEEP UPPER TROUGH/CLOSED LOW OVER THE NORTHWEST...

PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
CONFIDENCE: AVERAGE TO BELOW AVERAGE.

THE NAM/UKMET ARE STRUGGLING WITH THE DETAILS OF HOW MUCH
SHORTWAVE ENERGY EJECTS FROM THE PARENT LOW OVER THE ERN NOPAC ON
SUNDAY AND BEYOND.  THEY ARE FLATTER/FASTER BY THE TIME THE LEAD
SHORTWAVE MAKES IT ACROSS THE ROCKIES AND THE FRONT RANGE...WHILE
THE NAM MANAGED TO CLOSE TWO MID LEVEL CENTERS OFF THE PAC NW
COAST WHERE OTHER MODELS LEFT ROOM FOR A CLOSED CENTER BUT
GENERALLY REMAINED OPEN.  THE 12Z GFS CONTINUITY REMAINED VERY
GOOD WITH THE SHORTWAVE MAKING ITS WAY INLAND AND THEN STARTS TO
CLIMB THE WESTERN PERIPHERY OF A SOUTHEAST U.S. RIDGE.  BY LATE IN
DAY 3...THE ECMWF NOW KEEPS HEIGHTS LOWER ACROSS THE PAC NW INTO
SW CANADA WHICH LOOKS PLAUSABLE GIVEN THE UPSTREAM LOW AND WHERE
THE MID/UPPER LEVEL JET CROSSES THE WATERS OF THE ERN NOPAC.

...DEEP UPPER TROUGH/CLOSED LOW MOVING FROM THE OH VALLEY THROUGH
THE MID-ATLANTIC/NORTHEAST...

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

THE TREND OVER THE PAST FEW RUNS TOWARDS STRENGTHENING THE CLOSED
LOW OVER CONTINUED IN THE 12Z NCEP/NON NCEP MODELS ALIKE AS THEY
MOVE THE LOW OVER THE MID ATLANTIC REGION AND INTO THE MID
ATLANTIC REGION.  THE NAM CERTAINLY SPED UP THE FOREWARD MOTION OF
THE SYSTEM COMPARED WITH ITS RUN FROM 23/12Z.  THE GFS HAS BETTER
RUN TO RUN CONTINUITY.  ONE POINT OF AGREEMENT AMONG NEARLY THE
ENTIRE GLOBAL SUITE IS THAT THE LOW IS MOVING FASTER THAN IN
PREVIOUS RUNS BY THE END OF DAY 3.

...MID LEVEL SHORTWAVE TROUGH EJECTING OUT ACROSS THE CENTRAL
PLAINS/MIDWEST SUN NIGHT/MON...

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

THE 12Z NAM DEAMPLIFIED THE MID LEVEL SHORTWAVE TROUGH EJECTING
NEWD OUT INTO THE CNTRL PLAINS SUN NIGHT AND MOVING INTO THE
MIDWEST BY EARLY MON.  THIS GOT THE NAM INTO BETTER AGREEMENT WITH
OTHER MODELS BUT IT REMAINED A FAST OUTLIER AND STILL ON THE
STRONG SIDE OF THE GUIDANCE.  EVEN THOUGH THE GFS ALSO HAS SOME
TIMING DIFFERENCES WITH THIS FEATURE...THE RUN TO RUN CONTINUITY
WAS PRETTY GOOD AND HAD STRONG SUPPORT FROM THE ECMWF.  THE UKMET
HAD THE WEAKEST REFLECTION OF A TROF RUNNING ALONG THE TOP OF THE
RIDGE...SO HEIGHTS TENDED TO BE A BIT HIGHER IN THIS PART OF THE
COUNTRY WHEN COMPARED WITH THE OTHER MODELS.  STILL GAVE THE NOD
TO A GFS/ECMWF BLEND GIVEN THEIR AGREEMENT...RUN TO RUN
CONSISTENCY AND SUPPORT FROM THEIR RESPECTIVE ENSEMBLES.

...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