Prognostic Meteorological Discussion
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000
FXUS10 KWNH 190458
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1257 AM EDT TUE AUG 19 2014

VALID AUG 19/0000 UTC THRU AUG 22/1200 UTC

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


00Z GFS/NAM INITIALIZATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
INITIALIZATION ERRORS WITH THE NAM/GFS DO NOT SEEM TO DEGRADE
THEIR SHORT RANGE FORECASTS.


DEEP-LAYERED CYCLONE MOVING TOWARDS THE DESERT SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CANADIAN COMPROMISE
CONFIDENCE: AVERAGE

THE NON-GFS GUIDANCE HAS SHOWN SOME SIGNIFICANT FLIP-FLOPPING IN
THEIR FORECASTS CONCERNING THIS SYSTEM, LOWERING CONFIDENCE IN ANY
NON-GFS SOLUTION RIGHT OFF THE BAT.  TO BE FAIR, THE CYCLONE IS
DROPPING TOWARDS A COL POINT IN THE MID-LEVEL FLOW, WHICH NORMALLY
LEADS TO GREATER THAN AVERAGE UNCERTAINTY, MODEL GUIDANCE OR
OTHERWISE.  SPEAKING OF NON-GFS GUIDANCE, THE 12Z CANADIAN IS NOW
THE SLOWEST/MOST WESTERLY SOLUTION AMONGST THE GUIDANCE THU/FRI --
ITS USUAL BIAS.  A NON-CANADIAN COMPROMISE IS PREFERRED WITH
AVERAGE CONFIDENCE CONSIDERING THE POOR DAY-TO-DAY CONTINUITY SEEN
IN THE NON-GFS GUIDANCE.


TROUGH MOVING THROUGH THE NORTHERN CONTINENTAL DIVIDE
LEADING SHORTWAVE MOVING THROUGH THE DAKOTAS WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF COMPROMISE
CONFIDENCE: AVERAGE

THE 12Z UKMET/12Z CANADIAN ARE WEAKER THAN THE OTHER GUIDANCE,
INCLUDING THE 12Z ECMWF/18Z GEFS MEANS, WITH THIS SYSTEM.  THE
BEST 12Z GLOBAL ENSEMBLE CLUSTERING WITH THIS SYSTEM SUPPORTS THE
00Z GFS/12Z ECMWF SOLUTIONS, WHICH ARE PREFERRED WITH ONLY AVERAGE
CONFIDENCE CONSIDERING THE ABOVE AVERAGE SPREAD SEEN IN THE
DETERMINISTIC AND 12Z GLOBAL ENSEMBLE GUIDANCE.


SYSTEM MOVING ACROSS THE GREAT LAKES & NORTHEAST
SURFACE LOW NEAR THE VIRGINIA CAPES FRIDAY MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THIS MID-LEVEL SYSTEM IS EXPECTED TO PROGRESS UNDER THE BASE OF AN
INCREASINGLY STRONG AND QUASI-STATIONARY NORTHERN STREAM
RIDGE/CLOSED HIGH WITH TIME WHICH SHOULD KEEP IT STRONG AND
PROGRESSIVE.  THE 12Z UKMET FAILED IN THE STRENGTH DEPARTMENT
ALOFT, AND BECAUSE OF THIS, FALLS OUTSIDE THE 12Z GLOBAL ENSEMBLE
CLUSTERING BY FRIDAY MORNING WITH THE SURFACE LOW NEAR NC AND THE
VIRGINIA CAPES.  A NON-UKMET COMPROMISE IS ADVISED HERE WITH ABOVE
AVERAGE CONFIDENCE BASED UPON THE SYNOPTIC PATTERN IN WHICH THE
SYSTEM IS EMBEDDED.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ROTH

$$





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