Prognostic Meteorological Discussion
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FXUS10 KWNH 231653
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1252 PM EDT TUE SEP 23 2014

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

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

12Z NAM/GFS EVALUATION ALONG WITH PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z
NAM/GFS WHICH IMPACTED THEIR FORECASTS.


CLOSED LOW ALOFT OVER THE SOUTHEAST...WEAKENING WITH TIME
INVERTED TROUGH/SURFACE LOW ALONG THE EASTERN SEABOARD
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM / 00Z ECMWF THROUGH 00Z/26
            00Z ECMWF AFTER 00Z/26
CONFIDENCE: BELOW AVERAGE

MODELS SHOWING TRENDS HAVE MOSTLY INDICATED WWD MOVEMENT TOWARD
THE EAST COAST VERSUS FURTHER OFFSHORE OVER THE PAST 24 HOURS. THE
ECMWF...HOWEVER...HAS BEEN RATHER CONSISTENT...AND IS LIKELY
CLOSEST TO THE ENSEMBLE MEANS THROUGHOUT THE SHORT RANGE
PERIOD...THROUGH 00Z/27. THE ECMWF IS TOWARD THE SRN SIDE OF THE
ENSEMBLE MEANS THROUGH 00Z/26 SO WHEN BLENDED WITH THE QUICKER 12Z
NAM...A DECENT COMPROMISE IS ACHIEVED. AFTER 00Z/26...THE NAM IS
LIKELY TOO FAST...AND ENSEMBLE LOW POSITIONS SUPPORT SOMETHING
CLOSER TO THE 00Z ECMWF.


UPPER TROUGH MOVING FROM THE NRN PLAINS TO THE UPPER MISS VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z UKMET BLEND
CONFIDENCE: AVERAGE

THE 00Z UKMET STANDS OUT MOST AGAINST THE LATEST MODEL
CONSENSUS...WITH THE REMAINING MODELS FORMING AN ACCEPTABLE
COMPROMISE.


MID-LEVEL LOW FORECAST TO ORGANIZE OVER TEXAS THROUGH THE WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS / 00Z ECMWF BLEND
CONFIDENCE: BELOW AVERAGE

THERE IS VERY BROAD AGREEMENT WITH ALL OF THE LATEST GUIDANCE
HERE...BUT LESS SO ACROSS THE WRN GULF COAST. THE 00Z UKMET STANDS
OUT WITH A STRONGER MID-LEVEL WAVE COMING INTO THE COAST BY FRI
MORNING DUE TO A MORE NEUTRAL ORIENTATION WITH THE CNTRL/SRN
PLAINS MID-UPPER LEVEL TROUGH COMPARED TO THE REMAINING GUIDANCE.

THE BROAD AGREEMENT OUTSIDE OF THE UKMET IS BEST AVERAGED OUT WITH
A BLEND OF THE 12Z GFS AND 00Z ECMWF. HOWEVER...NO MODEL APPEARS
COMPLETELY UNUSABLE ACROSS TEXAS...WITH THE EXCEPTION OF THE 00Z
UKMET WHICH APPEARS TOO AGGRESSIVE ALONG THE GULF COAST WITH
VORTICITY NEAR A REMNANT FRONTAL BOUNDARY ACROSS THE GULF.
CONFIDENCE IS REDUCED DUE TO THE ILL DEFINED NATURE OF SYSTEMS.


LARGE UPPER TROUGH ALONG THE WEST COAST THROUGH FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM...12Z GFS...00Z ECMWF BLEND
CONFIDENCE: AVERAGE

ENSEMBLE MEANS SUPPORT AN UPPER TROUGH TIMING/POSITION CLOSE TO
THE 12Z NAM...12Z GFS...00Z ECMWF WHILE THE 00Z UKMET APPEARS FAST
INTO THE WEST AND THE 00Z CMC SLOW.

...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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