Prognostic Meteorological Discussion
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000
FXUS10 KWNH 280639
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
139 AM EST WED JAN 28 2015

VALID JAN 28/0000 UTC THRU JAN 31/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


DEPARTING NEW ENGLAND COASTAL STORM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM/ECMWF/UKMET/CMC INITIALIZED THE SURFACE LOW LOCATED
BETWEEN CAPE COD AND NOVA SCOTIA AT 00Z/28 6-7 MB TOO DEEP AND
SLIGHTLY SOUTHWEST OF THE ANALYSIS BUT THE 00Z GFS ANALYSIS WAS
CLOSE TO OBSERVATIONS IN BOTH INTENSITY AND POSITION. ALL OF THE
MODELS WEAKEN THE LOW THROUGH THE DAY ON WED WITH ONLY MINOR
INTENSITY DIFFERENCES.

REGARDING POSITION...THE LATEST DETERMINISTIC/ENSEMBLE MEAN
GUIDANCE SHOWS VERY GOOD AGREEMENT THROUGH THE DAY ON WED. GIVEN
IMPACTS TIED TO THE STORM ARE QUICKLY FADING...AND THE 00Z GFS
AGREES BEST ON THE INITIAL STRENGTH/POSITION...A SIMPLE 00Z GFS
SOLUTION WILL BE PREFERRED...BUT OTHER MODELS CERTAINLY HAVE
UTILITY HERE.


MID-LEVEL SHORTWAVE REACHING THE CENTRAL PLAINS LATE WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE LATEST MODELS SHOW SUFFICIENT AGREEMENT HERE TO SUPPORT A
GENERAL MODEL COMPROMISE FOR THE PREFERENCE. ALTHOUGH THERE HAS
BEEN SOME RUN TO RUN VARIABILITY IN TIMING...THESE DIFFERENCES ARE
MINOR AND WITHIN THE NOISE OF EXPECTED RUN TO RUN CHANGES.


MID-LEVEL SHORTWAVE REACHING THE N-CNTRL U.S. LATE WED
EVOLVING NEGATIVELY TILTED UPPER TROUGH ACROSS THE NORTHEAST BY
  FRI AND COASTAL NEW ENGLAND SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 21Z SREF MEAN OR NON 00Z CMC COMPROMISE THROUGH 12Z/30
    21Z SREF FROM 12Z/30-12Z/31
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THERE IS DECENT MODEL AGREEMENT FROM THE SURFACE THROUGH THE
MID-LEVELS WITH THIS SYSTEM THROUGH DAY 2...12Z/30. BEYOND
12Z/30...SPREAD INCREASES REGARDING THE POSITION OF A NEGATIVELY
TILTED MID-LEVEL TROUGH OFF OF THE NORTHEAST COAST AND POSSIBLE
CLOSED LOW DEVELOPMENT. THIS IMPACTS WHERE A SURFACE LOW WILL
DEVELOP WITH THE ENSEMBLE SCATTER LOW PLOTS SHOWING A WIDE RANGE
OF POSSIBILITIES BY 12Z/31...BUT FEEL THE MANY OF THE 00Z
DETERMINISTIC MODELS GET TOO CLOSE TO THE COAST OF MAINE GIVEN
THEY LIE ON THE WESTERN EDGE OF THE ENSEMBLE MEMBERS. THE ENSEMBLE
MEANS...BEST REPRESENTED BY THE 21Z SREF MEAN...SHOW A POSITION A
BIT FARTHER EAST THAN THE 00Z DETERMINISTIC CONSENSUS. THE 00Z
ECMWF APPEARS TO HAVE ADJUSTED TOWARD A MORE FAVORABLE POSITION
WITH THE UPPER LOW...CLOSER TO THE COAST COMPARED TO ITS 12Z
RUN...AND HAS SUPPORT FROM THE MULTI-MODEL CONSENSUS OUTSIDE OF
THE SOUTHWARD DISPLACED 00Z CMC BY 12Z/31.


CLOSED LOW ACROSS THE SOUTHWEST BY THE END OF THE WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS/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
00Z GFS AND 00Z ECMWF...WITH NEWER MODEL RUNS ADJUSTING ABOUT THE
BLENDED GFS/ECMWF POSITION.


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

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

OTTO

$$





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