Prognostic Meteorological Discussion
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FXUS10 KWNH 261651
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1251 PM EDT FRI AUG 26 2016

VALID AUG 26/1200 UTC THRU AUG 30/0000 UTC

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

12Z NAM/GFS EVALUATION...INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

LOW AMPLITUDE SHORTWAVE CLIPPING NRN NEW ENGLAND TODAY/TONIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM.


LOW-LEVEL SHORTWAVE LIFTING NEWD FROM THE PLAINS TONIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE

OUTSIDE OF THE STRONGER NAM...THE MODELS ARE IN GOOD AGREEMENT
WITH THIS SYSTEM.


UPPER TROUGH CROSSING THE N-CNTRL U.S. SAT...LIKELY REACHING NEW
  ENGLAND ON SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z NAM REMAINS A BIT SLOWER AND DEEPER WITH THIS SYSTEM WHILE
THE 00Z CMC IS THE MOST PROGRESSIVE SOLUTION. THE 12Z GFS/00Z
UKMET AND 00Z ECMWF ARE WELL CLUSTERED WITH THEIR SOLUTIONS IN
BETWEEN...AND A CONSENSUS OF THESE SOLUTIONS WILL BE PREFERRED.


UPPER TROUGH DROPPING SOUTH THROUGH BRITISH COLUMBIA ON SAT
COLD FRONT MOVING THROUGH THE NRN PLAINS SUN NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF
CONFIDENCE: AVERAGE

THE 00Z CMC GRADUALLY BECOMES A MODESTLY DEEPER AND MORE
PROGRESSIVE SOLUTION WITH THIS SYSTEM...WHEREAS THE 12Z NAM TENDS
TO ALSO BE SOMEWHAT DEEPER THAN THE MODEL CONSENSUS BUT IS  SLOWER
THAN THE CONSENSUS. THE 12Z GFS/00Z UKMET AND 00Z ECMWF ALL
CLUSTER TOGETHER IN BETWEEN THE NAM AND CMC CAMPS. WILL PREFER THE
GFS/UKMET/ECMWF CLUSTER GIVEN THEIR AGREEMENT TO THE LATEST
ENSEMBLE MEANS.


UPPER TROUGH DIGGING SOUTH OFFSHORE BRITISH COLUMBIA BY MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z NAM CONSENSUS
CONFIDENCE: AVERAGE

THE 12Z NAM IS QUICKER TO BRING THE UPPER TROUGH INTO THE PAC NW
COAST COMPARED TO THE REMAINING DETERMINISTIC/ENSEMBLE GUIDANCE.
THERE IS REASONABLE AGREEMENT IN THE REMAINING MODEL GUIDANCE.


WEAK MID LEVEL TROUGH OVER THE SOUTHWEST THIS WEEKEND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE

WHILE THERE IS BROAD AGREEMENT WITH THE EVOLUTION OF THIS
FEATURE...THE 12Z GFS/00Z ECMWF ARE IN THE MIDDLE OF THE LATEST
SPREAD WITH BETTER AGREEMENT OVERALL COMPARED TO YESTERDAY.
STILL...PREFER TO STAY CLOSER TO THE MIDDLE AND AWAY FROM THE
EDGES/OUTLIERS IN THE GUIDANCE.


LOW PRESSURE APPROACHING THE SOUTH FL AND THE KEYS BY SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS...00Z ECMWF MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE

A BLEND OF THE STRONGER/NORTH 00Z ECMWF AND WEAKER/SOUTH 12Z GFS
WORKS WELL HERE THROUGH EARLY SUN AS THE DIFFERENCES BETWEEN THE
TWO MODELS ARE SMALL ENOUGH AND FIT THE LATEST SOUTHWARD TRENDS IN
THE ENSEMBLE LOWS TO BE JUST SOUTH OF THE KEYS SUN MORNING. THE
00Z ECMWF DOES END UP A BIT CLOSER TO THE FL PENINSULA WITH THE
LOW BY MON...WHICH IS A BIT TOWARD THE RIGHT SIDE OF THE LATEST
ENSEMBLE LOW PLOTS. GIVEN THE DEVIATION IN THE 00Z ECMWF FROM THE
REMAINING CONSENSUS IN POSITION...AND THE FACT THAT THE 00Z
UKMET/CMC ARE STRONGER AND UNSUPPORTED AT THIS TIME BY ENOUGH OF
THE REMAINING GUIDANCE...A 12Z GFS...00Z ECMWF MEAN BLEND IS
PREFERRED.


WEAK MID LEVEL LOW CENTER NEAR THE WESTERN GULF COAST ON SAT/SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE 00Z UKMET/CMC ARE QUITE A BIT STRONGER WITH THIS FEATURE...AND
WHILE ENSEMBLE TRENDS SHOW MORE SUPPORT FOR A STRONGER SYSTEM
COMPARED TO YESTERDAY...THE LACK OF SUPPORT FOR THE 00Z UKMET/CMC
BY THE LATEST NAM/GFS/ECMWF PRECLUDES THEM BEING INCLUDED IN THE
PREFERENCE. WHILE THE NAM IS NOT OVERLY STRONG WITH THE
FEATURE...IT DOES SHOW THE PRESENCE OF NUMEROUS SMALLER SCALE
VORTICITY MAXIMA AROUND THE LOW CENTER WHICH IS NOT SUPPORTED IN
THE REMAINING DETERMINISTIC GUIDANCE. THIS LEAVES A GFS/ECMWF
BLEND WHICH IS REASONABLY CLOSE TO A CONSENSUS OF THE LATEST
ENSEMBLE GUIDANCE.

OTTO


...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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