Prognostic Meteorological Discussion
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000
FXUS10 KWNH 281701
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
100 PM EDT SUN AUG 28 2016

VALID AUG 28/1200 UTC THRU SEP 01/0000 UTC

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

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


UPPER TROUGH CROSSING NEW ENGLAND ON MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.


UPPER TROUGH TRACKING ACROSS SOUTHERN CANADA THROUGH MID-WEEK
COLD FRONT CROSSING THE NORTHERN PLAINS/GREAT LAKES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM...12Z GFS AND 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WHILE THE CMC HAS TRENDED WEAKER WITH THE UPPER TROUGH OVER
ONTARIO...THE 00Z CMC REMAINS STRONGER AND CERTAINLY FASTER THAN
THE DETERMINISTIC CONSENSUS STARTING ON TUE. BY WED...THE 00Z
UKMET ENDS UP A BIT SLOWER...WITH THE 12Z NAM/GFS AND 00Z ECMWF
FORMING A GOOD CLUSTER IN THE MIDDLE...CLOSEST TO THE LATEST
ENSEMBLE MEANS.


UPPER TROUGH DIGGING SOUTH OFFSHORE BRITISH COLUMBIA BY MON
ENERGY PIVOTING INTO THE WEST COAST BY LATE TUES/WED
LEAD SHORTWAVE CROSSING NORTHERN CA ON TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: AVERAGE

MINOR TIMING/STRENGTH DIFFERENCES EXIST WITH THE LATEST SUITE OF
MODELS REGARDING BOTH THE LARGE UPPER LOW SINKING SOUTH OFF OF THE
BRITISH COLUMBIA COASTLINE AND A COMPACT VORTICITY MAX ADVANCING
INTO THE COAST OF NRN CA ON TUE. WHILE THE 12Z GFS HAS BEEN A BIT
SLOWER...AND 12Z ECMWF FASTER...COMPARED TO THE CONSENSUS
REGARDING THE COMPACT VORT MAX...A BLEND OF THEIR TIMING MATCHES
THE NAM/UKMET/CMC. GIVEN THE GFS/ECMWF REPRESENT THE ENDS OF THE
ENSEMBLE SPREAD OF TIMING WITH THIS FEATURE...AND THE REMAINING
UPPER PATTERN MATCHES REASONABLY WELL WITH THE WELL CLUSTERED
DETERMINISTIC/ENSEMBLE GUIDANCE...A GENERAL MODEL COMPROMISE
SHOULD WORK WELL FOR THIS SYSTEM.


MID-UPPER LEVEL TROUGH OVER THE SOUTHWEST TODAY...WEAKENING TOWARD
  THE PLAINS THROUGH WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z NAM CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WHILE THERE IS BROAD AGREEMENT WITH THE EVOLUTION OF THIS
FEATURE...THE 12Z NAM ENDS UP ON THE STRONGER SIDE OF THE LATEST
GUIDANCE.


LOW PRESSURE APPROACHING THE FL KEYS/STRAITS
MOVING INTO THE GULF OF MEXICO MON/TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z NAM CONSENSUS
CONFIDENCE: AVERAGE

THERE IS GENERALLY GOOD AGREEMENT OUTSIDE OF THE 12Z NAM...WHICH
ENDS UP PRODUCING MULTIPLE VORTICITY MAXIMA IN THE VICINITY OF THE
FLORIDA PENINSULA...AND TAKES THE TRACK OF A SURFACE LOW MUCH
FARTHER EAST THAN THE 12Z GFS/00Z ECMWF/00Z UKMET/00Z CMC. THE
ENSEMBLE SCATTER LOW PLOTS SHOW MUCH BETTER AGREEMENT WITH THEIR
00Z/28 CYCLE COMPARED TO PREVIOUS RUNS AND CLUSTER RELATIVELY WELL
WITH THE NON-NAM CONSENSUS. THERE IS A SMALLER CLUSTER OF LOW
PLOTS DEPICTED ON THE ENSEMBLES BETWEEN THE GFS/ECMWF/UKMET/CMC
CONSENSUS AND THE WRN FLORIDA COASTLINE WED EVENING...BUT THESE
ARE NOT IN THE MAJORITY.


WEAK MID LEVEL LOW OVER THE WESTERN GULF INTO EARLY NEXT WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS...00Z ECMWF...00Z UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z GFS/00Z ECMWF/00Z UKMET SHOW THE BEST AGREEMENT WITH ONE
ANOTHER DESPITE SOME MINOR DIFFERENCES WITH PLACEMENT OF THE
MID-LEVEL CENTER. RUN TO RUN CONSISTENCY IS ALSO RATHER GOOD IN
THESE MODELS. THE 00Z CMC IS WEAKEST AND MOST SOUTH...WHILE THE
12Z NAM DEVELOPS MULTIPLE SMALLER SCALE VORTICITY MAXIMA NOT
DEPICTED IN THE OTHER GUIDANCE OF COMPARABLE STRENGTH TO THE
SYSTEM NEAR THE TEXAS COAST.


MID LEVEL LOW APPROACHING THE SOUTHEAST
TROPICAL DEPRESSION EIGHT TRACKING TOWARD THE MID-ATLANTIC COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF ARE CLOSEST TO 15Z NHC ADVISORY

WHILE THE 12Z GFS...00Z ECMWF..00Z UKMET SHOW GOOD OVERALL
AGREEMENT WITH THE 15Z NHC ADVISORY TRACK FOR T.D. EIGHT...THE
UKMET IS STRONGER THAN THE GFS/ECMWF. NHC BRINGS T.D. EIGHT TO
WEAK TROPICAL STORM STATUS BY SUN EVENING. REFER TO THE NHC FOR
THE MOST UP TO DATE INFORMATION ON THIS SYSTEM.

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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