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Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0643Z Apr 23, 2014)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
243 AM EDT WED APR 23 2014

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

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

00Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


MID LEVEL TROUGH/CLOSED LOW IMPACTING NEW ENGLAND THROUGH MIDWEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE NAM REMAINS A LITTLE CLOSER TO THE NEW ENGLAND COAST IN
CLOSING OFF A MID-LEVEL CENTER LATE TODAY...AND THIS IS ALSO TRUE
AT THE SURFACE COMPARED TO THE REMAINING MODEL CONSENSUS.
HOWEVER...THE STRENGTH OF THE NAM LOW IS COMPARABLE TO THE
REMAINING MODEL GUIDANCE AND GIVEN THE SHORT TERM NATURE OF THIS
FEATURE...THE NAM IS WITHIN REASON LEADING TO A GENERAL MODEL
COMPROMISE. NO MAJOR CHANGES SEEN HERE IN THE 00Z ECMWF/UKMET/CMC
COMPARED TO THIER 12Z RUNS.


CURRENT UPPER LEVEL TROUGH OUT WEST...REACHING THE PLAINS ON THU
SECONDARY COLD FRONT DROPPING SOUTH THROUGH THE UPPER MIDWEST BY
THE SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 70% 00Z ECMWF / 30% 00Z GFS BLEND
CONFIDENCE: A LITTLE BELOW AVERAGE

THERE HAS BEEN GENERAL A TREND IN THE GUIDANCE TO BE SLIGHTLY
SLOWER AND NORTH WITH A CLOSED MID-LEVEL LOW THAT FORMS NEAR THE
U.S.-CANADIAN THU MORNING. THIS TRENDS CAUSES THE COLD FRONTAL
PROGRESSION TO BE SLOWER THROUGH THE OHIO VALLEY ON THU/FRI. THE
LATEST ENSEMBLES SHOW THAT THE EC MEMBERS HAVE TRENDED
NORTH...WHILE THE GEFS MEMBERS HAVE TRENDED SOUTH. THE
LATEST...12Z/22 ECMWF MEMBERS SHOW A SIGNIFICANT TREND TO THE
NORTH WITH THE CLOSED LOW COMPARED TO THEIR PREVIOUS 3 CYCLES
WHICH ARE SOUTH. HOWEVER...GIVEN SIMILAR TRENDS SEEN IN THE 12Z
UKMET/CMC...IT APPEARS TO BE THE NCEP CAMP VERSUS THE NON-NCEP
CAMP AT THE MOMENT.

THE 00Z ECMWF/UKMET MODELS HAVE NUDGED IN THE DIRECTION OF THE
NCEP CAMP...BUT NOT BY MUCH. THERE IS ENOUGH A NUDGE TO CONTINUE
PREFERRING A SOLUTION IN THE MIDDLE...CLOSEST TO A ECMWF/GFS
BLEND...WITH MORE WEIGHT TOWARD THE 00Z ECMWF. GIVEN THE 00Z
ECMWF/UKMET/CMC ARE CONTINUING TO SHOW A SLOWER TRACK WITH THE
COLD FRONT...WE CANNONT CHALK UP THE CHANGE SEEN IN THE 12Z/22
GUIDANCE TO A SINGLE ERRANT RUN. THE CURRENT AMPLIFIED RIDGE OVER
THE CNTRL U.S. WOULD ARGUE FOR A SLOWER COLD FRONTAL
PROGRESSION...SIMILAR TO THE NON-NCEP CAMP...BUT ALSO FOR THE
CLOSED LOW TO BE FARTHER SOUTH...SIMILAR TO THE NCEP CAMP GIVEN
THE RIDGE ALOFT EXTENDING THROUGH ONTARIO. SOME OF THE OPPOSING
TRENDS CONTINUE TO KEEP CONFIDENCE A BIT BELOW AVERAGE.


UPPER LEVEL TROUGHING AFFECTING THE WRN U.S. FROM THU THROUGH SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE UNTIL 00Z/SAT
            00Z GFS/ECMWF/UKMET BLEND AFTER 00Z/SAT
CONFIDENCE: AVERAGE

RECENT TRENDS HAVE SHOWN SOME CONVERGENCE SUCH THAT THERE IS NOW A
BROAD CONSENSUS OUTSIDE OF THE FASTER 00Z NAM REGARDING THE UPPER
TROUGH AS IT REACHES THE SOUTHWEST SAT MORNING. THIS NON-NAM
CONSENSUS IS CURRENTLY IN THE MIDDLE TO SLOWER SIDE COMPARED TO
THE SLOWER ECMWF ENSEMBLE MEMBERS AND FASTER GEFS ENSEMBLE
MEMBERS. HOWEVER...THE NAM IS SIMILAR ALONG THE WEST COAST TO THE
REMAINING MODELS UP UNTIL 00Z/26. THE NEW 00Z CMC IS JUST A TAD
SLOWER THAN THE GFS/ECMWF/UKMET AND ENSEMBLE MEAN CONSENSUS BY
12Z/SAT...SO THE 00Z CMC IS NOT PREFERRED ALONG WITH THE 00Z
NAM...LEAVING THE GFS/ECMWF/UKMET TOWARD THE MIDDLE.


www.wpc.ncep.noaa.gov/html/model2.shtml...

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