Prognostic Meteorological Discussion
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FXUS10 KWNH 311719
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
119 PM EDT THU JUL 31 2014

VALID JUL 31/1200 UTC THRU AUG 04/0000 UTC

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

...AN EVALUATION OF THE 12Z NAM/GFS ALONG WITH PRELIMINARY
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...MEAN TROF CONTINUING TO ANCHOR THE EASTERN U.S...
...COASTAL BAROCLINIC ZONE...

PRELIMINARY PREFERENCE: BLEND OF THE 00Z ECMWF WITH THE 06Z
GEFS/00Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: AVERAGE

A PERSISTENT LONGWAVE TROF POSITIONED ACROSS THE EASTERN PORTION
OF THE CONUS WILL MAINTAIN ANOMALOUS IN NATURE THROUGH THE
WEEKEND. 500-MB HEIGHT ANOMALIES ARE FORECAST TO BE ABOUT 2
STANDARD DEVIATIONS BELOW CLIMATOLOGY. WITHIN THE NORTHWESTERLY
FLOW ON THE WESTERN FRINGE OF THE BROAD CIRCULATION...A NUMBER OF
IMPULSES WILL SLIDE THROUGH THE CENTER OF THE COUNTRY AND
EVENTUALLY MATERIALIZE ACROSS THE DEEP SOUTH/SOUTHEASTERN U.S.
EVENTUALLY THE EASTERN EXTENT OF THE UPPER TROF BEGINS TO DRIFT
WESTWARD AS A 594-DM ATLANTIC RIDGE BEGINS TO ADVANCE TOWARD THE
WEST. BY 03/0000Z...THE 12Z NAM/09Z SREF MEAN ARE WEST OF THE 00Z
CMC/UKMET WHILE THE 12Z GFS/00Z ECMWF SIT SOMEWHERE IN THE MIDDLE
WITH REGARD TO THE EASTERN PLACEMENT OF THE UPPER TROF. WILL GO
AHEAD AND FAVOR THIS MIDDLE GROUND UNTIL FURTHER GUIDANCE ARRIVES.
PREFER TO USE THE 06Z GEFS MEAN OVER THE 12Z GFS AS THE FORMER
FOLLOWS THE 00Z ECMWF SUITE A LITTLE MORE CLOSELY.


...MID-LEVEL ENERGY IMPACTING THE CENTRAL GREAT BASIN/UPPER
INTERMOUNTAIN WEST THROUGH SATURDAY...

PRELIMINARY PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: AVERAGE

ENERGY TRACKING UP AND OVER A WESTERN U.S. RIDGE WILL BE A FOCUS
FOR CONVECTION DURING THE NEXT FEW DAYS. THIS FEATURE IS WELL
REPRESENTED IN THE GUIDANCE WITH A POSITION IN THE VICINITY OF
EASTERN WA/NORTHERN ID BY 02/0000Z. SPREAD DOES GROW ALTHOUGH THE
SYSTEM ENDS UP LIFTING INTO SOUTHERN ALBERTA AT THAT POINT. THE
MODEL PREFERENCE WILL BE A GENERAL MODEL COMPROMISE TO ACCOUNT FOR
THE SMALLER-SCALE DIFFERENCES IN TIMING.


...SHORTWAVES OVER THE SOUTHWESTERN CONUS THIS WEEKEND...

PRELIMINARY PREFERENCE: A NON-00Z UKMET MODEL BLEND
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS CONTINUE TO SHOW SOME SORT OF DISTURBANCE EVOLVING OUT
OF NORTHWESTERN MEXICO REACHING THE DESERT SOUTHWEST BY THE LATTER
PART OF THE WEEKEND. WITH THE EXCEPTION OF THE 00Z UKMET...THE
MODELS ARE SHOW THIS SYSTEM ACROSS THE SOUTHWESTERN STATES BY
04/0000Z. WPC WILL RECOMMEND A NON-00Z UKMET GIVEN THE OUTLYING
NATURE OF ITS SOLUTION.


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

RUBIN-OSTER

$$





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