Prognostic Meteorological Discussion
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FXUS10 KWNH 231844
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
144 PM EST MON JAN 23 2017

VALID JAN 23/1200 UTC THRU JAN 27/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF

...CLOSED LOW LIFTING ACROSS THE MID-ATLANTIC/COASTAL NEW
ENGLAND...
...STRONG SURFACE LOW LIFTING NORTHEAST ALONG THE COAST...

PREFERENCE: BLEND OF THE 12Z GFS/12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

ALL OF THE MODELS TAKE THE STRONG MID/UPPER LOW OVER THE SOUTHERN
MID-ATLANTIC STATES THIS MORNING OFF TO THE NORTHEAST OVER THE
NEXT 48 HOURS TO OFFSHORE SOUTHERN NEW ENGLAND AND THEN OUT TO SEA
WHILE ALSO BECOME MORE ELONGATED IN A NEGATIVELY-TILTED FASHION.
THIS WILL DRIVE SURFACE LOW PRESSURE OVER THE MID-ATLANTIC COASTAL
PLAIN GRADUALLY OFFSHORE AND UP TOWARD THE GULF OF ME. THE 12Z NAM
ON TUES TENDS TO TUCK LOW PRESSURE IN A LITTLE CLOSER THE NJ COAST
COMPARED TO THE MODEL CONSENSUS...AND THEN GRADUALLY BY WED IT IS
ENDS UP BEING A BIT FARTHER EAST. BY WED...THE 12Z UKMET FOCUSES
ITS LOW CENTER LEFT OF THE MODEL CONSENSUS. THE 12Z GFS AND 12Z
ECMWF TEND TO REPRESENT THE MULTI-MODEL CONSENSUS AND A BLEND OF
THESE SOLUTIONS WILL BE PREFERRED.


...SURFACE LOW DROPPING SOUTH DOWN OFF THE WEST COAST THROUGH
TUES...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

A STRONG SURFACE LOW OFF THE COAST OF THE PACIFIC NORTHWEST WILL
STEADILY WEAKEN TONIGHT THROUGH TUES WHILE DROPPING SOUTH OFFSHORE
CA AS ITS UPPER SUPPORT WEAKENS SIGNIFICANTLY. THERE IS MINIMAL
MASS FIELD SPREAD AMONG THE MODELS WITH THIS SYSTEM...SO A GENERAL
MODEL COMPROMISE WILL BE PREFERRED.


...LONGWAVE TROUGH/SURFACE LOW OVER THE WEST EJECTING OUT INTO THE
PLAINS...
...ENERGY LIFTING NORTHEAST INTO THE GREAT LAKES REGION BY WED...
...ATTENDANT COLD FRONT ADVANCING THROUGH THE EASTERN U.S. THROUGH
THURS...

PREFERENCE: BLEND OF THE 12Z UKMET/12Z ECMWF
CONFIDENCE: AVERAGE

THE UPPER TROUGH MOVING INTO THE WEST WILL ADVANCE EAST TUES AND
WED AND CROSS THE PLAINS STATES BEFORE THEN LIFTING THROUGH THE
MIDWEST THROUGH THURS ALONG WITH A CLOSED MID LEVEL LOW CENTER.
THE MODELS AGREE IN TAKING SURFACE LOW PRESSURE OVER THE GREAT
BASIN OFF TO THE EAST AND REDEVELOPING IT OVER THE CENTRAL PLAINS
TUES BEFORE LIFTING NORTHEAST INTO THE GREAT LAKES REGION BY LATE
WED. A TRAILING COLD FRONT WILL SWEEP TOWARD THE EAST COAST BY
LATE THURS. THE 12Z NAM AND 12Z GFS HAVE BOTH TRENDED A LITTLE
FARTHER SOUTH WITH THE LOW TRACKS OUT ACROSS THE CENTRAL
PLAINS/MIDWEST...BUT ARE STILL A TAD NORTH OF THE 12Z NON-NCEP
MODEL CONSENSUS. THE 12Z GEFS MEAN AND 00Z ECENS MEAN SUGGEST A
SOLUTION A LITTLE CLOSER TO THE NON-NCEP CAMP OVERALL...AND
ESPECIALLY A CONSENSUS OF THE UKMET AND ECMWF. WILL SUGGEST A
UKMET/ECMWF BLEND AS A RESULT AT THIS TIME.


...SHORTWAVE APPROACHING THE WEST COAST LATE WED/EARLY THURS...

PREFERENCE: 12Z ECMWF
CONFIDENCE: AVERAGE

A PROGRESSIVE SHORTWAVE TROUGH WILL ADVANCE TOWARD THE WEST COAST
BY LATE WED AND WILL BEGIN TO SHEAR INLAND BY THURS. THE 12Z GFS
BECOMES THE SLOWEST SOLUTION...WITH THE 12Z NAM TENDING TO BE ON
THE STRONGER SIDE OF THE MODEL SPECTRUM. THE NON-NCEP MODELS ARE
GENERALLY FLATTER AND SOMEWHAT MORE PROGRESSIVE. WILL LEAN TOWARD
THE MORE SHEARED OUT CONSENSUS...LED BY THE 12Z ECMWF.


...SHORTWAVE DROPPING ACROSS THE UPPER MIDWEST/GREAT LAKES
WED/THURS...

PREFERENCE: BLEND OF THE 12Z GFS/12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

ADDITIONAL SHORTWAVE ENERGY WILL BE DROPPING SOUTHEAST ACROSS THE
UPPER MIDWEST AND GREAT LAKES REGION WED AND THURS. THE 12Z NAM
APPEARS TO BE A BIT TOO STRONG WITH THIS ENERGY COMPARED TO THE
OTHER GLOBAL MODELS. WILL PREFER TO LEAN TOWARD A CONSENSUS OF THE
12Z GFS AND 12Z ECMWF WHICH IS CLOSE TO THE MODEL CONSENSUS.


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

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

ORRISON

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