Prognostic Meteorological Discussion
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000
FXUS10 KWNH 290637
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 AM EDT THU SEP 29 2016

VALID SEP 29/0000 UTC THRU OCT 02/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF


...DEVELOPING WEST COAST UPPER TROUGH/CLOSED LOW...
...LEAD SHORTWAVE EJECTING THROUGH THE INTERIOR...

PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF...MAIN UPPER
TROUGH/CLOSED LOW
            NON-GFS CONSENSUS....WITH THE LEAD SHORTWAVE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

ALL OF THE MODELS SHOW A DEEP UPPER TROUGH AND ASSOCIATED CLOSE
LOW DIGGING SOUTHEAST AND TOWARD THE WEST COAST THROUGH THE
PERIOD...WITH A LEAD SHORTWAVE THAT IS EXPECTED TO DROP INITIALLY
SOUTH AND THEN EJECTING INLAND ACROSS THE INTERMOUNTAIN WEST. THE
00Z GFS APPEARS TO BE A RELATIVELY SLOW AND DEEP OUTLIER WITH THE
LEAD SHORTWAVE AS IT EJECTS INLAND AHEAD OF THE STRONGER HEIGHT
FALLS DROPPING SOUTH ALONG THE WEST COAST. THE REMAINING MODELS
ARE WELL CLUSTERED ON A SOMEWHAT WEAKER AND FASTER SOLUTION AS THE
ENERGY SHEARS OUT OVER THE INTERIOR. REGARDING THE DEEP UPPER
TROUGH/CLOSED LOW BY THE END OF THE PERIOD...THE 00Z UKMET APPEARS
TO FOCUS A BIT MORE ENERGY NORTH AND EAST OF THE MODEL CONSENSUS
AS THIS ENERGY DROPS SOUTH OFFSHORE BRITISH COLUMBIA AND THEN
OFFSHORE THE PACIFIC NORTHWEST. THE 00Z NAM AND 00Z GFS ARE BOTH
DROPPING THE ENERGY PERHAPS A TAD SOUTH OF THE CONSENSUS BY THE
END OF THE PERIOD...WITH THE 00Z ECMWF JUST A LITTLE NORTH OF THIS
CAMP. WILL FAVOR A NON-GFS CONSENSUS WITH THE LEAD SHORTWAVE...BUT
WILL SUGGEST A GFS/ECMWF COMPROMISE WITH THE MAIN UPPER
TROUGH/CLOSED LOW JUST OFF THE WEST COAST BY THE END OF THE PERIOD.


...DEEP CYCLONE ACROSS MIDWEST DOUBLING BACK TOWARDS MI...

PREFERENCE: BLEND OF THE 00Z GFS/00Z ECMWF
CONFIDENCE: ABOVE AVERAGE

THE MODELS ARE IN VERY GOOD AGREEMENT WITH THEIR MASS FIELDS
THROUGH 48 HOURS WITH THE UPPER LOW OVER THE OH VALLEY.
THEREAFTER...ALL OF THE MODELS ALSO INDICATE THE UPPER LOW LIFTING
GRADUALLY BACK NORTH INTO MI WITH SOME MINOR TIMING DIFFERENCES.
THE 00Z GFS AND 00Z ECMWF ARE NOW CLUSTERING VERY WELL WITH EACH
OTHER...WITH THE 00Z NAM JUST A TAD WEST OF THE MODEL CONSENSUS.
THE GFS/ECMWF CAMP IS RATHER WELL SUPPORTED BY THE LATEST
UKMET/CMC SOLUTIONS AS WELL...AND THEREFORE WILL MAINTAIN
CONTINUITY IN PREFERRING A GFS/ECMWF BLEND.


...CLOSED LOW LIFTING OUT OF THE SOUTHWEST...
...SHORTWAVE LIFTING MOVING THROUGH ND FRIDAY...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE GENERALLY SHOWS GOOD AGREEMENT WITH THESE SYSTEMS. A
GENERAL MODEL COMPROMISE WILL THEREFORE BE PREFERRED AT THIS TIME.


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

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

ORRISON

$$





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