Prognostic Meteorological Discussion
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000
FXUS10 KWNH 241754
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1254 PM EST MON NOV 24 2014

VALID NOV 24/1200 UTC THRU NOV 28/0000 UTC

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

12Z NAM/GFS/UKMET/CMC EVALUATION INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

LOW PRESSURE TRACKING INTO SERN CANADA FROM THE GREAT LAKES TODAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THIS FEATURE.


LOW PRESSURE TRACKING UP THE EAST COAST TUE NIGHT INTO THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  12Z UKMET...09Z SREF...00Z EC MEAN COMPROMISE
CONFIDENCE:  AVERAGE

THE 12Z NAM/GFS/CMC CONTINUE STEADILY TRACKING QUICKER WITH THE
MID-LEVEL SHORTWAVE DIVING THROUGH THE SOUTHEAST...AND WHILE THESE
TRENDS ARE ALSO SEEN IN THE 00Z ECMWF/12Z UKMET...THEY ARE LESS
PRONOUNCED IN THESE TWO MODELS. THE LATEST ENSEMBLE MEMBERS FROM
00Z/24 INDICATE THE 00Z ECMWF IS ON THE WRN SIDE OF THE OVERALL
SPREAD REGARDING THE SURFACE LOW NEAR THE 40N/70W BENCHMARK BY
00Z/27...WHILE THE 12Z NAM IS ON THE FAR NERN SIDE OF THE
MEMBERS...FOLLOWED NEXT BY THE 12Z GFS.

THE PREFERENCE IS TO BE IN THE MIDDLE OF THE ENSEMBLE SPREAD...IN
BETWEEN THE GFS/ECMWF. THE 12Z UKMET FITS CLOSEST TO THIS
PREFERENCE...WHICH IS APPROXIMATELY AN EVEN BLEND OF THE 12Z
GFS/00Z ECMWF. THE 09Z SREF MEAN AND 00Z EC MEAN COULD ALSO FIT AS
A REASONABLE COMPROMISE CLOSE TO THE PREFERRED POSITION...BUT
THEIR SURFACE LOWS ARE LIKELY A BIT TOO WEAK.


WEAK SURFACE LOW TRACKING ACROSS THE PLAINS INTO THE APPALACHIANS
ON TUE-WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  12Z NAM / 12Z UKMET BLEND
CONFIDENCE:  AVERAGE

ANY TRENDS SEEN HAVE BEEN A BIT SOUTH WITH THIS WAVE TUE
NIGHT...AND THE LATEST ENSEMBLE GUIDANCE SUPPORTS THESE TRENDS.
THE 12Z GFS/00Z ECMWF FALL ON EITHER SIDE OF THE MIDDLE GROUND
SOLUTION...WITH THE 12Z NAM/UKMET MAKING UP THE PREFERRED POSITION
CLOSEST TO THE MEANS WITH ONLY MINOR RUN TO RUN CHANGES.


SHORTWAVES IMPACTING THE PAC NW ON THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:  12Z GFS / 12Z UKMET BLEND
CONFIDENCE:  A LITTLE BELOW AVERAGE

ENSEMBLE SPREAD HAS CONTINUED TO SHRINK REGARDING 500 MB HEIGHTS
AND RIDGING EXTENDING INTO SWRN CANADA SINCE THIS TIME YESTERDAY.
IN FACT...THE LATEST DETERMINISTIC SPREAD IS RATHER SMALL...BUT
THE 00Z ECMWF REMAINS FLATTEST WITH THE RIDGE IN THE PAC NW.
HOWEVER...THE 12Z UKMET HAS TRENDED TOWARD THE ECMWF...WHILE THE
12Z CMC HAS TRENDED TOWARD THE 12Z GFS. THEREFORE THE PREFERENCE
WILL MAKE MINOR ADJUSTMENTS TOWARD THE 1Z UKMET...WITH A 12Z
GFS/UKMET FITTING A REASONABLE COMPROMISE CONSISTENT WITH TRENDS
AND THE LATEST ENSEMBLE GUIDANCE.


...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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