Prognostic Meteorological Discussion
Issued by NWS

000
FXUS10 KWNH 230441
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1241 AM EDT THU MAY 23 2013

VALID MAY 23/0000 UTC THRU MAY 26/1200 UTC

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


00Z NAM/GFS EVALUATION

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


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

PREFERENCE: 12Z ECENS MEAN
CONFIDENCE: AVERAGE

THE LATEST GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE DETAILS OF
THIS DEEP UPPER LOW THROUGH LATE FRI...AND THEN THERE IS A GRADUAL
INCREASE IN SPREAD THEREAFTER AS THE MODELS SHOW SOME DISAGREEMENT
WITH HOW UPSTREAM SHORTWAVE ENERGY DIGS IN FROM THE GULF OF AK.
ALL OF THE MODELS SUPPORT TWO CLOSED LOW CENTERS EVOLVING BY THE
END OF THE PERIOD...WITH ONE OVER SWRN CANADA AND ONE OFFSHORE THE
PAC NW BY SAT. HOWEVER...THE 00Z GFS IS MUCH WEAKER WITH THIS
ENERGY OFFSHORE THE PAC NW COMPARED TO THE CONSENSUS. THE 12Z
ECMWF THOUGH GRADUALLY BECOMES THE DEEPEST MODEL BY EARLY SUN. THE
12Z GEM GLOBAL HAS THIS NEW UPPER LOW OFFSHORE THE PAC NW TWD THE
END OF THE PERIOD...BUT APPEARS TO BE DIGGING ITS ENERGY TOO FAR
SOUTH BY SAT NIGHT/SUN. THE 18Z GEFS MEAN AND 12Z ECENS MEAN BOTH
SUPPORT A CLOSED CENTER OVER SRN B.C...BUT THE 18Z GEFS MEAN IS
NOT SUPPORTING AS MUCH ENERGY OFF THE PAC NW. THE 12Z ECENS MEAN
DOES SUPPORT THIS THOUGH AND HAS SUPPORT FROM THE 12Z UKMET. WILL
FAVOR THE 12Z ECENS MEAN ATTM.


...DEEP UPPER TROUGH/CLOSED LOW MOVING FROM THE MIDWEST TO THE
NORTHEAST...

PREFERENCE: 12Z ECENS MEAN
CONFIDENCE: BELOW AVERAGE

THE UPPER TROUGH ATTM OVER THE MIDWEST WILL BE DIGGING SEWD
THROUGH THE OH VLY AND INTO THE MID-ATLANTIC REGION THROUGH FRI
AND IS LIKELY TO CLOSED OFF OVER THIS REGION ON SAT AS ADDITIONAL
UPSTREAM SHORTWAVE ENERGY DIGGING IN FROM THE GRT LAKES REGION
ARRIVES AND INTENSIFIES THE HT FALLS. THE HT FALLS ARE THEN
EXPECTED TO PIVOT AND BECOME NEG TILTED SAT INTO SUN WITH THE
ENERGY LIFTING UP ACROSS NEW ENGLAND. THE 12Z ECMWF IS THE
FARTHEST SOUTH WITH ITS CLOSED LOW THROUGH FRI...WITH THE 00Z
NAM/00Z GFS/12Z GEM GLOBAL AND ESP THE 12Z UKMET FARTHER NORTH.
THE 12Z UKMET IS AN OUTLIER SOLN SFC AND ALOFT WITH THIS SYS IN
FOCUSING ITS ENERGY SO FAR NORTH AND ALSO BEING QUICKER TO EJECT
THE HT FALLS OFF TO THE NORTHEAST. IN TIME...THE 00Z NAM APPEARS
TO BE TOO FAR NORTH AND QUICK AS WELL. THE 18Z GEFS MEAN AND THE
12Z ECENS MEAN SUGGEST THE 12Z ECMWF MAY BE A LITTLE TOO FAR SOUTH
WITH ITS CLOSED LOW AND PERHAPS TOO SLOW TO LIFT IT OUT OF THE
MID-ATLANTIC AND INTO NEW ENGLAND. CONFIDENCE IS SOMEWHAT
LIMITED...BUT FOR NOW WILL SPLIT THE MODEL DIFFS BY LEANING TWD
THE 12Z ECENS MEAN FOR THE MASS FIELDS.


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

ORRISON

$$