Prognostic Meteorological Discussion
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000
FXUS10 KWNH 301651
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1250 PM EDT SUN AUG 30 2015

VALID AUG 30/1200 UTC THRU SEP 03/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS


...SHORTWAVE/ASSOCIATED FRONT SKIRTING NORTHERN NEW ENGLAND EARLY
MON...

PREFERENCE: NON-UKMET CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE UPPER FLOW GRADUALLY BEGINS TO AMPLIFY OVER EASTERN CANADA BY
EARLY NEXT WEEK. MODELS EXHIBIT SOME VARIATION IN TIMING ALTHOUGH
THE BIGGER DIFFERENCE IS WITH REGARD TO THE AMPLITUDE. THE 00Z
UKMET SHOWS A TAD MORE AMPLIFICATION WITH A TROUGH DIGGING ACROSS
THE REGION VERSUS THE GLOBAL MODEL CONSENSUS. A NON-UKMET
CONSENSUS WILL BE PREFERRED.


...SHORTWAVE LIFTING THROUGH THE SOUTHEAST TO THE MID-ATLANTIC...
...RETROGRADING ENERGY FOCUSING FROM THE SOUTHERN PLAINS TO THE OH
VALLEY...

PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: AVERAGE

WATER VAPOR IMAGERY SHOWS A POTENT UPPER LOW CROSSING INTO EXTREME
SOUTHERN AL WHICH WILL SLOWLY OPEN UP INTO A TROUGH AXIS THAT
PIVOTS THROUGH THE INTERIOR SOUTHEAST AND INTO THE MID-ATLANTIC
REGION THROUGH MON. THERE IS A GENERAL CONSENSUS THAT THE SYSTEM
WILL LIFT NORTH AND EAST TOWARD THE LOWER MID-ATLANTIC DURING THE
NEXT 24 TO 36 HOURS. THE STRONGER MODEL CLUSTERING FAVORS A BLEND
OF THE 12Z GFS AND 00Z ECMWF...WITH THE 00Z UKMET APPEARING A
LITTLE TOO WEAK AND PROGRESSIVE...AND THE 00Z CMC EVENTUALLY A
LITTLE TOO SLOW. THE 12Z NAM DOES LEND SUPPORT FOR THE GFS/ECMWF
CAMP.

MEANWHILE...TO THE WEST...A SEPARATE WEAKNESS IN THE FLOW WILL
ELONGATE FROM THE SOUTHERN PLAINS NORTHEAST TO THE OH VALLEY WHICH
WILL IN PART BE ENHANCED BY SHORTWAVE ENERGY CURRENTLY DROPPING
SOUTH ACROSS THE MID MS VALLEY. THERE ARE SOME RELATIVELY MINOR
PLACEMENT DIFFERENCES WITH THE INDIVIDUAL VORT CENTERS AND
ESPECIALLY OVER THE OH VALLEY. THE 12Z NAM HAS A SLOWER ADVANCE OF
ENERGY EAST THROUGH THE OH VALLEY AND THE 00Z UKMET IS RATHER WEAK
WITH THIS ENERGY. THE 12Z GFS AND 00Z ECMWF CLUSTER BETTER AND SO
A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED.


...UPPER TROUGH ACROSS THE NORTHWESTERN U.S...

PREFERENCE: NON-UKMET CONSENSUS
CONFIDENCE: AVERAGE

A SERIES OF SHORTWAVES TRACKING THROUGH THE PACIFIC NORTHWEST AND
ADJACENT LOCATIONS DOWNSTREAM WILL HELP MAINTAIN A
PERSISTENT/ANOMALOUS LONGWAVE TROUGH ACROSS THE REGION THROUGH THE
MIDDLE OF NEXT WEEK. THE 00Z UKMET IS A BIT SLOWER IN EJECTING A
SHORTWAVE TOWARD SOUTHERN SASKATCHEWAN ON MON. UPSTREAM THE MODELS
SHOW GOOD AGREEMENT ON THE LARGER SCALE EVOLUTION OF THE HEIGHT
FALLS...AND SO A NON-UKMET CONSENSUS WILL BE PREFERRED.


...REMNANTS OF ERIKA...

THE 12Z NAM/00Z UKMET AND 00Z CMC INSIST ON THE REMNANTS OF FORMER
T.S. ERIKA REGENERATING INTO A CLOSED LOW CENTER OVER THE EASTERN
GULF OF MEXICO AND LIFTING NORTH-NORTHEAST INTO NORTHERN FL. THE
12Z GFS ALSO FAVORS A WEAK CIRCULATION...BUT THE 00Z ECMWF
MAINTAINS A WAVE AXIS. PLEASE CONSULT THE LATEST NHC TROPICAL
WEATHER OUTLOOK FOR MORE INFORMATION ON THIS SYSTEM.


...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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