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Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0633Z Nov 21, 2014)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
133 AM EST FRI NOV 21 2014

VALID NOV 21/0000 UTC THRU NOV 24/1200 UTC

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

...AN EVALUATION OF THE 00Z MODEL GUIDANCE ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...UPPER TROF MOVING FROM THE GREAT LAKES TOWARD THE NORTHEASTERN
U.S...

FINAL PREFERENCE: ANY AVAILABLE MODEL
FORECAST CONFIDENCE: HIGH

THE PATTERN IS QUITE AMPLIFIED OVER THE NORTHEASTERN U.S. TO BEGIN
THE PERIOD. MODELS AGREE THIS SYSTEM WILL MOVE QUICKLY TO THE EAST
EXITING INTO THE CANADIAN MARITIMES BY LATE FRIDAY. NO MEANINGFUL
DIFFERENCES ARE IDENTIFIED SO ANY MODEL APPEARS REASONABLE HERE.


...INITIAL SHORTWAVE OVER NORTHERN CA...
...EVENTUAL NEGATIVELY-TILTED TROF MOVING UP THE MS RIVER...
...SURFACE CYCLOGENESIS ACROSS THE UPPER GREAT LAKES BY LATE
SUNDAY...

FINAL PREFERENCE: BLEND OF THE 00Z GFS/ECMWF
FORECAST CONFIDENCE: AVERAGE

A SPLIT IN THE MID-LATITUDE FLOW IS NOTED WITH A PRONOUNCED
SOUTHERN STREAM SHORTWAVE CURRENTLY ADVANCING THROUGH NORTHERN CA.
THE SYSTEM IS EXPECTED TO CONTINUE TO DIG AS IT ADVANCES INTO
NORTHERN MX AND ATTAINS A CLOSED UPPER CENTER BY 22/0600Z.
RELATIVE TO THE OTHER GUIDANCE...THE 00Z CMC/21Z SREF MEAN SEEM
SLOW WITH THIS PROGRESSION...PARTICULARLY AS THE FEATURE
APPROACHES THE BIG BEND OF TX. AS THE SYSTEM MIGRATES THROUGH THE
ARKLATEX AND EVENTUALLY INTO THE LOWER MO VALLEY...THE MODELS VARY
WITH THE TIMING AND AMPLITUDE OF THE SHORTWAVE. RELATIVE TO THE
REASONABLY CLUSTERED ENSEMBLES WITHIN THE THE 564-DM SPAGHETTI
PLOT...THE 00Z/12Z CMC/UKMET CONTINUE TO LOOK SLOW. BY
24/0000Z...THE 00Z/12Z CMC/UKMET DEFINITELY BECOME SLOW OUTLIERS
RELATIVE TO THE WELL CLUSTERED 00Z GEFS/12Z ECMWF ENSEMBLE MEANS.
GIVEN THIS ASSESSMENT...THE WPC PREFERENCE IS A BLEND OF THE 00Z
GFS/ECMWF. THIS PREFERRED COMBINATION CONTAINS SOME TIMING
DIFFERENCES WITH THE DEEPENING SURFACE LOW BUT STILL RESIDES WELL
WITHIN THE ENSEMBLE SPREAD.


...HEIGHT FALLS REACHING THE PACIFIC NORTHWEST BY SATURDAY
MORNING...
...DEEP UPPER TROF/STRONG COLD FRONT OVER THE CENTER OF THE
COUNTRY...

FINAL PREFERENCE: BLEND OF THE 00Z GFS/ECMWF
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

A LONGWAVE TROF ADVANCING INTO THE PACIFIC NORTHWEST BY 22/1200Z
WILL EVENTUALLY HELP DIG A SIGNIFICANT UPPER TROF ACROSS THE
CENTER OF THE COUNTRY. MODELS SUGGEST A STRONG CLOSED LOW WILL
MOVE EASTWARD ACROSS THE NORTH-CENTRAL CONUS ON SUNDAY WITH
PRONOUNCED LOBES OF VORTICITY ADVANCING THROUGH THE SOUTHERN
PLAINS. THIS FULL-LATITUDE TROF WILL DRAG A STRONG BAROCLINIC ZONE
EASTWARD WITH THE 00Z NAM BEING SLOWER WHILE THE 00Z UKMET IS MUCH
FASTER WITH THE PROGRESSION OF THIS BOUNDARY. THE REPRESENTATION
OF THIS SYSTEM BY THE 00Z GFS/ECMWF SEEMS REASONABLE AND FITS WELL
WITHIN THE MODEL CONSENSUS. THIS SOLUTION ALSO COMPLIMENTS THE
TIMING OF THE DOWNSTREAM SURFACE LOW LIFTING INTO THE GREAT LAKES
WELL.


...NEXT SHORTWAVE TO REACH THE PACIFIC NORTHWEST BY SUNDAY
MORNING...

FINAL PREFERENCE: BLEND OF THE 00Z GEFS/12Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: AVERAGE

ONCE THE CORE OF THE SHORTWAVE ENERGY ADVANCES TOWARD THE CENTRAL
U.S...AN ADDITIONAL DISTURBANCE IS EXPECTED TO MOVE THROUGH THE
PACIFIC NORTHWEST ON SUNDAY. THIS LOWER AMPLITUDE FEATURE SEEMS TO
BE REASONABLY RESOLVED BY THE GUIDANCE. THE 00Z CMC HAS ADJUSTED
FROM ITS PREVIOUS SOLUTION NOW JOINING THE GENERAL CONSENSUS.
THEREAFTER...THERE ARE DIFFERENCES IN HOW THE WESTERN EDGE OF THE
TROF IS SHAPED OVER THE INTERMOUNTAIN WEST. THE 12Z/00Z ECMWF
ENSEMBLE MEMBERS FAVOR MORE AMPLIFICATION AS NOTED IN THE PAST TWO
552-DM SPAGHETTI PLOTS. WILL SPLIT THE DIFFERENCE BETWEEN THESE
ENSEMBLE MEANS.


www.wpc.ncep.noaa.gov/html/model2.shtml...
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

RUBIN-OSTER