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Model Diagnostics Discussion
 
(Latest Discussion - Issued 0525Z Nov 01, 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
125 AM EDT SAT NOV 01 2014

VALID NOV 01/0000 UTC THRU NOV 04/1200 UTC

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


00Z MODEL EVALUATION...INCLUDING THE NAM/GFS AND UKMET


...DEEP TROUGH/CLOSED LOW AFFECTING THE EASTERN U.S...

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z UKMET
CONFIDENCE: AVERAGE

A DEEP UPPER TROUGH AND ASSOCIATED CLOSED LOW WILL BE IMPACTING
THE MID-ATLANTIC AND NORTHEAST OVER THE NEXT COUPLE OF DAYS AS
STRONG HEIGHT FALLS DIG THROUGH THE OH VALLEY AND THE CENTRAL AND
SOUTHERN APPALACHIANS. LOW PRESSURE INITIALLY OFFSHORE THE
MID-ATLANTIC STATES WILL LIFT NORTH-NORTHEAST TO EAST OF THE
BENCHMARK SATURDAY AFTERNOON. MEANWHILE...INTENSE HEIGHT FALLS
EJECTING OFFSHORE THE SC/NC COASTAL PLAIN BY LATE SATURDAY WILL
INVIGORATE A NEW AREA OF LOW PRESSURE OFFSHORE THE MID-ATLANTIC
STATES SATURDAY NIGHT WHICH WILL THEN LIFT NORTH-NORTHEAST AND
INTENSIFY INTO A POWERFUL STORM OFFSHORE NEW ENGLAND NEAR THE GULF
OF MAINE ON SUNDAY. THE 00Z NAM IS THE FARTHEST LEFT WITH THIS
MORE DOMINANT LOW CENTER...AND SUGGESTS THE LOW GOES IN BETWEEN
THE MAINE COASTLINE AND THE WESTERN TIP OF NOVA SCOTIA.
HOWEVER...THE 00Z GFS AND 00Z UKMET ARE VERY WELL CLUSTERED ON A
SOLUTION JUST A TAD EAST OF THE 00A NAM. THE GFS/NAM AND UKMET ALL
SUPPORT A CLOSED 500 MB CENTER RIDING NORTH THROUGH THE GULF OF
MAINE BY 12Z SUNDAY. THE NAM THOUGH IS THE DEEPEST SOLUTION. THE
12Z ECMWF IS A TAD SLOWER AND FARTHER EAST...WITH THE 12Z GEM THE
ABSOLUTE FARTHEST EAST AND SLOWEST. THE TREND IN THE 00Z NAM AND
00Z GFS IS TO BE A LITTLE FARTHER LEFT COMPARED TO THEIR PREV
RUNS...AND AFTER SEEING THE 00Z GEM REGIONAL...A SOLUTION CLOSE TO
THAT OF THE GFS AND UKMET SEEMS REASONABLE.


...TROUGH MIGRATING THROUGH THE WESTERN AND CENTRAL U.S...
...COLD FRONT SETTLING ACROSS THE MIDWEST AND DOWN TO THE SOUTHERN
PLAINS...

PREFERENCE: BLEND OF THE 00Z UKMET AND THE 12Z ECMWF
CONFIDENCE: AVERAGE 
 
THE MODELS CLUSTER FAIRLY WELL WITH THE UPPER TROUGH THAT
INITIALLY COMES INTO THE WEST THROUGH SATURDAY. A SPLIT IN THE
TROUGH OCCURS ON SUNDAY...WITH A NORTHERN STREAM PORTION OF THE
TROUGH PROGRESSING THROUGH THE NORTHERN ROCKIES/NORTHERN PLAINS
AND UPPER MIDWEST SUNDAY AND MONDAY. A SOUTHERN STREAM PORTION OF
THE TROUGH DIGS THROUGH THE SOUTHWEST U.S. AND THE FOUR CORNERS
REGION.

THE 00Z GFS GRADUALLY BECOMES A BIT MORE PROGRESSIVE THAN THE
MULTI-MODEL CONSENSUS WITH THE NORTHERN STREAM ENERGY AS IT EJECTS
ACROSS THE NORTHERN TIER OF THE NATION. THE 00Z NAM...00Z
UKMET...12Z ECMWF AND 12Z GEM ARE ALL A LITTLE SLOWER AND WELL
CLUSTERED ALOFT. AT THE SURFACE...A COLD FRONT ASSOCIATED WITH THE
HEIGHT FALLS WILL PROGRESS SOUTHEAST THROUGH THE UPPER MIDWEST AND
DRAPE DOWN TOWARD THE CENTRAL AND SOUTHERN PLAINS BY MONDAY AND
TUESDAY. THE 00Z NAM TENDS TO BE THE SLOWEST SOLUTION WITH
THIS...WITH THE 00Z UKMET AND 12Z ECMWF OVERALL A LITTLE FASTER
BUT ALSO SUPPORTED BY THE LATEST ECENS MEAN.

REGARDING THE SOUTHERN STREAM ENERGY...THERE IS GOOD AGREEMENT
WITH THIS PORTION OF THE TROUGH UNTIL MONDAY...WHEN THE 00Z NAM
SUGGESTS MORE TROUGH PROGRESSION OUT TOWARD THE SOUTHERN HIGH
PLAINS. THE 00Z GFS AND ESPECIALLY THE NON-NCEP MODELS HOLD MORE
ENERGY BACK OVER THE SOUTHWEST AND EVEN DIG ENERGY INTO NORTHWEST
MEXICO WITH SUGGESTION OF A CLOSED LOW DIGGING ACROSS HERE AS PER
THE 00Z UKMET AND 12Z ECMWF SOLUTIONS. THE RELATIVELY MORE
PROGRESSIVE NATURE OF THE GFS AND NAM WITH THIS SOUTHERN STREAM
ENERGY ON THE LARGER SCALE IS LIKELY A REASON FOR THESE SOLUTIONS
BEING A LITTLE SLOWER WITH THE FRONTAL PROGRESSION OVER THE
CENTRAL/SOUTHERN PLAINS...AS THERE WOULD BE A BIT MORE INTERACTION
BETWEEN THE TWO FEATURES AS COMPARED TO THE NON-NCEP SOLUTIONS BY
LATE MONDAY AND TUESDAY. OVERALL...WPC WILL PREFER A SOLUTION
TOWARD THE 12Z ECMWF AND 00Z UKMET WITH BOTH NORTHERN AND SOUTHERN
STREAM SYSTEMS.


...SHORTWAVE TROUGH AND COLD FRONT IMPACTING THE PACIFIC NORTHWEST
BY TUESDAY...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

A FAST-MOVING SHORTWAVE TGORUGH AND ASSOCIATED COLD FRONT WILL BE
IMPACTING COASTAL WA/OR AND THE CASCADES LATE MONDAY AND TUESDAY
WITH A MARKED INCREASE IN DEEP LAYER ONSHORE FLOW. ALL OF THE
MODELS INDICATE A STRONG PACIFIC JET PARALLELLING THE FRONT BY
EARLY TUESDAY ALONG WITH A DEEP MOISTURE FETCH. THERE IS LITTLE
DIFFERENCE WITH THE MODELS ON THE LARGER SCALE ALOFT OR AT THE
SURFACE...SO WILL PREFER A GENERAL MODEL COMPROMISE TO RESOLVE ANY
SMALLER SCALE DIFFERENCES AT THIS POINT.


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

ORRISON