THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


MODEL DIAGNOSTIC DISCUSSION


[Abbreviations and acronyms used in this product]
Geographic boundaries:    Map 1- [Color] [B/W Print Version]      Map 2 - [Color] [B/W Print Version]



MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1249 PM EDT FRI OCT 31 2014

VALID OCT 31/1200 UTC THRU NOV 04/0000 UTC

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

==================================================
12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES
==================================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==================================================

...TROUGH AFFECTING THE EASTERN U.S...

PREFERENCE: BLEND OF 12Z NAM/00Z ECMWF

THE GFS...NAM...ECMWF...AND UKMET CLUSTER FAIRLY WELL. ENSEMBLE
SPREAD IS AVERAGE OR BORDERING ON LESS THAN AVERAGE. YET SUBTLE
VARIATION IN THE HANDLING OF COASTAL LOW PRESSURE MAKES A LARGE
DIFFERENCE FOR SOME AREAS...PARTICULARLY MAINE. THE GFS HAS
CONSISTENTLY OFFERED MORE AGGRESSIVE SOLUTIONS IN WHICH THE
DEEPENING CYCLONE TRACKS CLOSER TO THE NEW ENGLAND
COAST...YIELDING A GREATER EXPANSE OF MODERATE OR HEAVY
PRECIPITATION INLAND. THE OPERATIONAL GFS CONTINUES A LITTLE LEFT
OF THE GEFS MEAN. RELATIVE TO CONSENSUS THE UKMET IS SLIGHTLY FAST
AND FARTHER EAST. THIS LEAVES THE NAM/ECMWF AS BEING MOST
REPRESENTATIVE OF THE MULTI-CYCLE CONSENSUS. THE LOBE OF COLD AIR
THAT SLIDES INTO THE SOUTHEAST U.S. BEHIND THIS SYSTEM IS
IMPRESSIVE WITH 850 MB TEMPERATURES 0 TO -5 C...OR 3 TO 4
DEVIATIONS BELOW CLIMATOLOGY.


...TROUGH MIGRATING THROUGH THE WESTERN AND CENTRAL U.S...

PREFERENCE: BLEND OF 12Z NAM/00Z ECMWF

MODELS HAVE BEEN CONSISTENT IN DEPICTING A POSITIVELY TILTED LARGE
SCALE TROUGH WITH A WELL DEFINED LEAD WAVE EJECTING TO THE
NORTHERN PLAINS AND A SEPARATE VORTICITY MAXIMUM PASSING THROUGH
THE SOUTHWEST U.S. THE LEAD WAVE HAS A BETTER DEFINED SURFACE
REFLECTION. AS WAS TRUE FOR THE EASTERN U.S. SYSTEM...THE
GFS/NAM/ECMWF/UKMET CLUSTER FAIRLY WELL...BUT THE NAM/ECMWF HAVE
BEEN A LITTLE MORE CONSISTENT REGARDING STRENGTH AND PLACEMENT.
THE 12Z GFS ALSO WORKS WELL HERE...BUT IT APPEARS A LITTLE FAST
WITH HEIGHT FALLS INTO THE SOUTHERN HIGH PLAINS AHEAD OF THE
SOUTHERN PORTION OF THE TROUGH.


...NEXT SYSTEM INTO THE PACIFIC NORTHWEST SUN/MON...

PREFERENCE: BLEND OF THE OPERATIONAL MODELS...EXCLUDING THE 00Z
CANADIAN

THE MODELS ARE HANDLING THE PATTERN WELL GIVEN THE EXISTENCE OF
LARGE SCALE...EVENLY SPACED WAVES AND LITTLE IN THE WAY OF SPLIT
FLOW. THE MOST NOTABLE OUTLIER WAS THE 00Z CANADIAN WHICH
UNDER-EMPHASIZES SHORTWAVE RIDGING POPPING UP INTO SOUTHWEST
CANADA ON MONDAY...WHILE OVER-EMPHASIZING SURFACE TROUGHING DOWN
THE COASTS OF WASHINGTON AND OREGON.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

BURKE




Last Updated: 1249 PM EDT FRI OCT 31 2014