Prognostic Meteorological Discussion
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000
FXUS10 KWNH 310441
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1240 AM EDT WED AUG 31 2016

VALID AUG 31/0000 UTC THRU SEP 03/1200 UTC

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

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

...TROUGH AMPLIFICATION INTO THE EASTERN U.S....
...ATTENDANT COLD FRONT PROGRESSION...

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

THE 00Z NAM AGAIN TENDS TO BE A BIT DEEPER AND A LITTLE SLOWER
THAN THE MULTI-MODEL CONSENSUS WITH THE TROUGH AMPLIFICATION INTO
THE EASTERN U.S. THROUGH THE END OF THE WEEK. THE 12Z UKMET AND
12Z CMC ARE A TAD MORE PROGRESSIVE BY COMPARISON. THE 00Z GFS AND
12Z ECMWF CLUSTERED NICELY TOGETHER IN BETWEEN CAMPS...AND SO A
BLEND OF THESE SOLUTIONS WILL BE PREFERRED.


...UPPER LOW/TROUGH DIGGING SOUTH OFFSHORE BRITISH COLUMBIA...
...HEIGHT FALLS ADVANCING ACROSS THE NORTHWEST THROUGH FRI/SAT...

PREFERENCE: 12Z ECMWF
CONFIDENCE: BELOW AVERAGE

THERE IS GENERALLY GOOD AGREEMENT WITH THE TIMING AND DEPTH OF THE
UPPER TROUGH THROUGH ABOUT 48 HOURS THAT DIGS SOUTH OFFSHORE
BRITISH COLUMBIA. THEREAFTER...MUCH MORE MODEL SPREAD IS NOTED AS
THE TROUGH ADVANCES EASTWARD ACROSS THE NORTHWEST U.S. THROUGH THE
END OF THE WEEK. THE 00Z NAM AND ESPECIALLY THE 00Z GFS AND 12Z
CMC BECOME SLOWER WITH THE EVOLUTION OF TROUGH AND CLOSED LOW BY
THE END OF THE PERIOD. THE 12Z UKMET IS THE MOST
PROGRESSIVE...WITH THE 12Z ECMWF IN BETWEEN THE UKMET AND GFS
SOLUTIONS. OVERALL THE BETTER ENSEMBLE SUPPORT FAVORS THE
ECMWF...SO WILL LEAN TOWARD THIS SOLUTION FOR NOW. CONFIDENCE
REMAINS LIMITED.


...SHEAR AXIS WEAKENING ACROSS THE SOUTHWEST/PLAINS...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS ARE IN GOOD AGREEMENT WITH THIS WEAKENING FEATURE...AND
A GENERAL MODEL COMPROMISE WILL BE PREFERRED.


...WAVE DEVELOPING ALONG THE SOUTHEAST COAST WED-THU...

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

THE MODELS ARE INDICATING SURFACE WAVE DEVELOPMENT OVER NORTHERN
FL AND THEN NORTHEAST ALONG A COASTAL TROUGH POSITIONED ALONG THE
GA/SC COAST...THERE REMAINS A BIT OF SPREAD WITH RESPECT TO THE
TIMING AND AMPLITUDE OF THIS FEATURE. ALL OF THE GUIDANCE SHOWS
THIS LOW CENTER LIFTING NORTHEAST ON THE HEELS OF T.D. EIGHT WHICH
WILL EXIT AWAY FROM THE EAST COAST. THE 12Z UKMET GRADUALLY
BECOMES THE SLOWEST SOLUTION AND IS A BIT FARTHER EAST WITH ITS
LOW TRACK VERSUS THE REMAINING GUIDANCE. THE 12Z CMC GRADUALLY
BECOMES THE STRONGEST SOLUTION. BETTER MODEL CLUSTERING FAVORS THE
00Z GFS AND 12Z ECMWF...AND A BLEND OF THESE SOLUTIONS WILL BE
PREFERRED.


...T.D. EIGHT MOVING OFF THE MID-ATLANTIC COAST...

PREFERENCE: PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY

THE 00Z GFS AND 12Z ECMWF ARE A TAD MORE PROGRESSIVE THAN THE 00Z
NAM/12Z UKMET AND 12Z CMC SOLUTIONS WITH T.D. EIGHT. THE 03Z NHC
FORECAST TRACK IS CLOSEST TO THE 00Z GFS OVERALL AND SHOWS THE
SYSTEM RECURVING AWAY FROM THE EAST COAST OVER THE NEXT COUPLE OF
DAYS. PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY FOR MORE
INFORMATION.


...T.D. NINE MOVING INTO THE GULF OF MEXICO...

PREFERENCE: PLEASE CONSULT THE LATEST NHC FORECAST ADVISORY

THE 03Z NHC FORECAST TRACK OF T.D. NINE IS CLOSEST TO A CONSENSUS
OF THE 00Z GFS AND 12Z ECMWF THROUGH THURS...AND THEN MORE TOWARD
THE INCREASINGLY PROGRESSIVE 12Z ECMWF THEREAFTER AS THE SYSTEM
RAPIDLY CROSSES NORTHERN FL AND ADVANCES JUST OFF THE SOUTHEAST
AND MID-ATLANTIC COASTS FRI AND SAT. THE 12Z CMC IS A SLOW OUTLIER
SOLUTION...WITH THE 00Z NAM ALSO RATHER SLOW AND FARTHEST TO THE
RIGHT. THE 12Z UKMET IS FARTHEST LEFT WITH THE SYSTEM...AND TAKES
THE SYSTEM WELL INLAND OVER THE SOUTHEAST COASTAL PLAIN. PLEASE
CONSULT THE LATEST QPFPFD FOR INFORMATION ON THE EXPECTED HEAVY
RAINFALL EXPECTED WITH THE SYSTEM...AND THE LATEST NHC FORECAST
ADVISORY FOR MORE INFORMATION ON T.D. NINE.

ORRISON

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

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

$$





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