Prognostic Meteorological Discussion
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000
FXUS10 KWNH 290454
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1254 AM EDT WED MAR 29 2017

VALID MAR 29/0000 UTC THRU APR 01/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...STRONG CLOSED LOW CROSSING THE CENTRAL/SOUTHERN PLAINS...
...ADVANCING EAST THROUGH THE MID MS/TN/OH VALLEYS BY THURS/FRI...
...ENERGY CROSSING THE MID-ATLANTIC BY FRI NIGHT...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

THE 00Z NAM BECOMES A BIT SLOWER THAN THE MODEL CONSENSUS BY 36
HOURS AND BEYOND WITH THE STRONG SOUTHERN STREAM CLOSED LOW/TROUGH
AND ACCOMPANYING SURFACE LOW EJECTING ACROSS THE CENTRAL/SOUTHERN
PLAINS AND THEN ADVANCING EAST ACROSS THE MID MS/TN/OH VALLEYS
THURS AND FRI BEFORE CROSSING THE MID-ATLANTIC FRI NIGHT. THE 12Z
UKMET GRADUALLY BECOMES FOCUSED TOO FAR SOUTH AND WITH ITS HEIGHT
FALLS OVER THE OH/TN VALLEYS ALONG WITH ITS SURFACE LOW. STRONGER
MODEL CLUSTERING IS FOCUSED TOWARD THE 00Z GFS AND 12Z ECMWF WITH
SUPPORT ALSO FROM THE 12Z CMC. A BLEND OF THESE SOLUTIONS WILL BE
SUGGESTED.


...TROUGH CROSSING THE NORTHERN TIER STATES WED THROUGH FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

THE MODELS HAVE A WEAK NORTHERN STREAM TROUGH CROSSING THE
NORTHERN PLAINS/UPPER MIDWEST AND GREAT LAKES REGION WED THROUGH
FRI BEFORE THE ENERGY THEN SCOOTS INTO NORTHERN NEW ENGLAND BY
SAT. THE 00Z GFS AND 12Z ECMWF TEND TO HAVE THE BEST CLUSTERING AS
THE 00Z NAM GETS TO BE TOO WEAK AND 12Z UKMET A TAD TOO
PROGRESSIVE. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED AT
THIS POINT.


...VIGOROUS TROUGH DIGGING INTO THE WEST ON THURS...
...STRONG CLOSED LOW OVER THE FOUR CORNERS BY FRI/SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A STRONG UPPER TROUGH WILL BE DIGGING ACROSS THE PACIFIC NORTHWEST
ON THURS AND THEN AMPLIFYING VIGOROUSLY INTO A CLOSED LOW ACROSS
THE FOUR CORNERS REGION FRI AND SAT. THE 00Z NAM BY FRI AND SAT
BECOMES A TAD FASTER THAN THE GLOBAL MODELS IN EJECTING THE CLOSED
LOW OFF TO THE EAST. THE 12Z UKMET BY THE END OF THE PERIOD
BECOMES A TAD SLOWER THAN THE MODEL CONSENSUS. THE 00Z GFS AND 12Z
ECMWF ARE WELL CLUSTERED ALONG THROUGH THE PERIOD WITH
TIMING...BUT EVENTUALLY THE GFS BECOMES A BIT MORE ROBUST WITH ITS
CLOSED LOW THAN ANY OTHER MODEL. THE GFS ALSO TENDS TO HAVE MORE
LOW PRESSURE FARTHER ACROSS THE CENTRAL ROCKIES AND INTO THE HIGH
PLAINS COMPARED TO THE REMAINING GUIDANCE. THE 12Z ECMWF APPEARS
MOST REASONABLE AT THIS POINT...AND WILL CONTINUE WITH THIS
PREFERENCE.


...NORTHERN STREAM TROUGH/FRONT CROSSING THE NORTHERN PLAINS FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS
CONFIDENCE: AVERAGE

THE NEXT NORTHERN STREAM TROUGH WILL CROSS THE NORTHERN PLAINS BY
FRI ALONG WITH A WEAK COLD FRONT. THE 12Z ECMWF AND TO A LESSER
EXTENT THE 00Z NAM APPEAR A BIT TOO SLOW WITH THIS. THE REMAINING
MODELS ARE A TAD MORE PROGRESSIVE. THE 00Z GFS APPEARS QUITE
REASONABLE WITH THIS SYSTEM AND WILL BE PREFERRED.

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

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

ORRISON

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