Prognostic Meteorological Discussion
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000
FXUS10 KWNH 251856
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM EDT MON JUL 25 2016

VALID JUL 25/1200 UTC THRU JUL 29/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES AND FORECAST
CONFIDENCE


...UPPER LEVEL LOW CROSSING THE NORTHERN GULF OF MEXICO TUE/WED...

PREFERENCE: NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE

THE 12Z NAM CONTINUES TO BE A BIT DEEPER AND FURTHER WEST WITH THE
UPPER LOW AS IT REACHES THE TX COAST TUE INTO WED. THE 12Z GFS IS
CLOSER TO THE CONSENSUS...AND IT BETTER SUPPORTED BY THE 00Z ECMWF
ENSEMBLE MEAN/12Z GEFS. GIVEN THE GOOD MODEL AGREEMENT...A NON NAM
BLEND IS PREFERRED.


...TROUGH OVER THE UPPER MIDWEST REACHING NEW ENGLAND TUE...

PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z NAM AND 12Z GFS WERE CLOSE TO THE CONSENSUS WITH THE SHORT
WAVE TRACKING ACROSS THE UPPER GREAT LAKES THROUGH QUEBEC INTO NEW
ENGLAND TUE...AS WELL AS THE SURFACE FRONT IT PUSHES TO THE COAST.
GIVEN THE GOOD MODEL AGREEMENT...A GENERAL MODEL BLEND IS
PREFERRED.


...DEVELOPING MID LEVEL TROUGH OVER THE PLAINS INTO THE MIDWEST
TUE INTO THU...

PREFERENCE: 12Z GFS/12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE 12Z NAM IS CLOSE TO THE CONSENSUS WITH THE SHORT WAVE TRACKING
OUT OF THE NORTHERN
ROCKIES/NORTHERN PLAINS ON THE SOUTHERN EDGE OF THE WESTERLIES
THAT DEVELOPS INTO A MID LEVEL TROUGH OVER THE MIDWEST/MID MS
VALLEY. HOWEVER...THE 12Z NAM BECOMES FASTER THAN THE CONSENSUS BY
THE END OF THE PERIOD. THE 12Z GFS IS ALSO CLOSE TO THE CONSENSUS
THROUGH WED... BUT ENDS UP FASTER THAN THE 12Z ECMWF BY 29/00Z.

THE FASTER 12Z GFS TIMING IS SUPPORTED BY THE 12Z GEFS MEAN
POSITION (WHILE THE SLOWER 12Z ECMWF IS SUPPORTED BY THE 00Z ECMWF
ENSEMBLE MEAN POSITION). GIVEN THE DIFFERENCES IN TIMING AT THE
END OF THE PERIOD...BLENDING THE TWO CAMPS (12Z GFS/12Z ECMWF)
SHOULD PROVIDE THE BEST SOLUTION...AND THIS BLEND IS PREFERRED.


...MID LEVEL TROUGH OVER THE PACIFIC NORTHWEST TUE INTO WED...

PREFERENCE: NON-ECMWF CONSENSUS
CONFIDENCE: AVERAGE

THE 12Z NAM IS CLOSE TO THE CONSENSUS WITH THE TIMING OF THE MID
LEVEL TROUGH ACROSS THE PACIFIC NORTHWEST/BRITISH COLUMBIA TUE
INTO WED. THE 12Z GFS CONTINUES ITS DEEPER TREND WITH THIS
FEATURE...BUT ITS TIMING WAS CLOSER TO THE CONSENSUS. THE 12Z
ECMWF HAS BECOME THE FASTER OUTLIER WITH THIS TROUGH...MUCH FASTER
THAN THE 12Z GFS/12Z UKMET/00Z ECMWF ENSEMBLE MEAN. BECAUSE OF
THIS...THE 12Z ECMWF WAS REMOVED FROM THE PREFERENCE.

HAYES

...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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