Prognostic Meteorological Discussion
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FXUS10 KWNH 271834
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
133 PM EST TUE JAN 27 2015

VALID JAN 27/1200 UTC THRU JAN 31/0000 UTC

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

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


...DEEP COASTAL STORM EXITING NEW ENGLAND...

PREFERENCE: NON-ECMWF CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE 12Z ECMWF IS A TAD SLOWER THAN THE GLOBAL MODEL CONSENSUS WITH
THE DEEP LAYER LOW CENTER GRADUALLY EXITING THE OFFSHORE WATERS OF
NEW ENGLAND. THE 12Z NAM/12Z GFS/12Z GEM AND 12Z UKMET SOLUTIONS
ARE ALL WELL CLUSTERED AROUND A SLIGHTLY MORE PROGRESSIVE SOLUTION
WHICH IS FAVORED BY THE LATEST GEFS MEAN AND ECENS MEAN. WILL
PREFER A NON-ECMWF CONSENSUS.


...WEAKENING CLOSED LOW MOVING INTO CALIFORNIA...
...ENERGY TRAVERSING THE GREAT BASIN THROUGH WEDNESDAY...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

A WEAKENING UPPER LOW MOVING NORTH THROUGH CALIFORNIA CURRENTLY
WILL BEGIN TO WEAKEN AND THEN BEGIN TO SHEAR EAST OVER TOP A RIDGE
AXIS FOCUSED OVER THE CENTRAL/SOUTHERN ROCKIES. THERE IS VERY GOOD
MODEL AGREEMENT WITH THE MASS FIELDS WITH THIS ENERGY AS IT
CROSSES THROUGH THE GREAT BASIN.


...SHORTWAVE TROUGHING/ENERGY CROSSING THE CENTRAL
PLAINS/MIDWEST...
...TROUGH AMPLIFICATION INTO THE NORTHEAST THROUGH
THURSDAY/FRIDAY...

PREFERENCE: 12Z GFS
CONFIDENCE: AVERAGE

SHORTWAVE ENERGY SHEARING OUT OF THE GREAT BASIN IS EXPECTED TO
ADVANCE EAST AND CROSS OUT THROUGH THE CENTRAL PLAINS AND MIDWEST
THROUGH THURSDAY. THE GUIDANCE DEPICTS ADDITIONAL NORTHERN STREAM
ENERGY DIGGING IN BEHIND THE LEAD SHORTWAVE...WITH A COMBINATION
OF THE TWO LEADING THE WAY FOR WHAT SHOULD BE A LARGER SCALE
TROUGH AMPLIFYING ACROSS THE GREAT LAKES/OHIO VALLEY AND NORTHEAST
THROUGH FRIDAY. SURFACE LOW PRESSURE WILL TRACK ACROSS THE
NORTHERN PLAINS AND THEN DIG ACROSS THE MIDWEST AND GREAT LAKES
REGION BEFORE ATTEMPTING TO REDEVELOP JUST OFFSHORE OF NEW ENGLAND
INTO THE GULF OF MAINE ON FRIDAY. OVERALL...THE 12Z ECMWF IS BIT
SLOWER AND DEEPER WITH THE SHORTWAVE EVOLUTION THROUGH THURSDAY
COMPARED TO THE GLOBAL MODEL CONSENSUS. THE 12Z GEM LIKE THE 12Z
ECMWF BECOMES A BIT SLOWER/DEEPER WITH THE LARGER SCALE TROUGH
THAT GRADUALLY IMPACTS THE GREAT LAKES/NORTHEAST BY FRIDAY. THE
12Z NAM/12Z GFS AND 12Z UKMET ARE ALL A BIT MORE PROGRESSIVE. THE
LATEST GEFS MEAN ALSO FAVORS THE MORE PROGRESSIVE CAMP. WILL FAVOR
THE MORE PROGRESSIVE CAMP LED BY THE GFS AT THIS TIME.


...UPPER TROUGH MOVING INTO THE SOUTHWEST BY THE END OF THE WEEK...

PREFERENCE: BLEND OF THE 12Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

THERE IS RELATIVELY MINOR SPREAD IN A SOMEWHAT BROAD UPPER TROUGH
MAKING ITS WAY TOWARD THE WEST COAST. BY FRIDAY...THE MODELS
DEPICT A LARGE UPPER LOW WITH A BIT OF A N/S ELONGATION STRETCHING
FROM THE GREAT BASIN SOUTH INTO THE NORTHERN BAJA PENINSULA.
STRONGER MODEL CLUSTERING OVERALL TENDS TO FAVOR A BLEND OF THE
12Z GFS AND 12Z ECMWF...AND THAT WILL BE THE PREFERENCE.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

$$





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