Prognostic Meteorological Discussion
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000
FXUS10 KWNH 300640
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 AM EDT TUE SEP 30 2014

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

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

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


...NEG-TILTING TROUGH/SURFACE LOW LIFTING THROUGH THE NORTHERN
PLAINS...

PREFERENCE: BLEND OF THE 00Z UKMET/00Z GEM AND THE 00Z ECMWF
CONFIDENCE: ABOVE AVERAGE

ALL OF THE MODELS SHOW A NEG-TILTING TROUGH AND ASSOCD CLOSED LOW
PIVOTING NWD UP THROUGH THE NRN PLAINS THROUGH WED ALONG WITH A
COMPACT AREA OF SFC LOW PRESSURE. THE 00Z GFS IS A LITTLE LEFT OF
THE GLOBAL MODEL CONSENSUS. THE 00Z NAM EVENTUALLY BECOMES A BIT
LEFT OF THE LARGER CLUSTERING BY WED AS THE ENERGY LIFTS INTO SRN
CANADA. THE 00Z GEM/00Z UKMET AND 00Z ECMWF CLUSTER TOGETHER VERY
WELL...SO WILL PREFER A BLEND OF THESE SOLNS.


...SPLIT FLOW TROUGHING IMPACTING THE PLAINS AND MIDWEST WED TO
FRI...
...SURFACE LOW DEVELOPING AND INTENSIFYING INTO THE GREAT LAKES
REGION...

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

THE MODELS INDICATE A STRONG NORTHERN STREAM TROUGH DIGGING INTO
THE NRN PLAINS AND UPR MIDWEST THURS AND FRI WHICH IS EXPECTED TO
ASSUME SOME NEG TILT AND POSSIBLY CLOSE OFF. MEANWHILE...A SRN
STREAM TROUGH ASSOCD WITH AT LEAST A PERIOD OF SPLIT FLOW OVER THE
CNTRL U.S. WILL BE DIGGING ACROSS THE ROCKIES AND DOWN INTO THE
SRN PLAINS.

ACROSS THE NRN PLAINS AND UPR MIDWEST...THE 00Z NAM IS NOTABLY
STRONGER WITH ITS HEIGHT FALLS. THE 00Z GEM/00Z UKMET AND 00Z
ECMWF ALL TRENDED A LITTLE STRONGER ALOFT AND FARTHER SOUTH WITH
THEIR RESPECTIVE HEIGHT FALLS AND THESE SOLNS ALL HAVE A CLOSED
LOW OVER THE UPR MS VLY BY EARLY FRI. THE 00Z GFS AGREES WITH THIS
SCENARIO EXCEPT IT IS PERHAPS JUST A TAD WEAKER AND A LITTLE MORE
PROGRESSIVE. THE GEFS MEAN AND ECENS MEAN CLUSTER RATHER WELL
TOGETHER AND SHOW AT LEAST BROAD SUPPORT FOR THE DETERMINISTIC
GFS/ECMWF SOLNS. A BLEND OF THE GFS AND ECMWF WILL STILL BE
PREFERRED ATTM WITH THE MORE DOMINANT NRN STREAM ENERGY.

REGARDING THE SRN STREAM TROUGH...THE 00Z GEM AND 00Z UKMET
TRENDED A BIT WEAKER AND TWD THE 00Z NAM/00Z GFS AND 00Z ECMWF
CONSENSUS RELATING TO THE SHORTWAVE TROUGH THAT DIGS ACROSS THE
CNTRL/SRN ROCKIES AND QUICKLY OUT ACROSS THE SRN PLAINS AND LWR MS
VLY. THE 00Z ECMWF HAS ALSO TRENDED A LITTLE SLOWER...BUT TWD THE
GLOBAL MODEL CONSENSUS. THE GEFS MEAN AND ECENS MEAN SUPPORT THE
LESS AMPLIFIED CONSENSUS AND THIS WILL BE PREFERRED LED BY A BLEND
OF THE GFS AND ECMWF.


...SHORTWAVE TROUGH DIGGING INTO THE MID-ATLANTIC/SOUTHERN NEW
ENGLAND...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS TAKE THE CLOSED LOW OVER THE LWR GRT LAKES REGION DOWN
ACROSS THE NRN MID-ATLANTIC AND THROUGH SRN NEW ENGLAND THROUGH
WED NIGHT AND THURS BEFORE THEN GOING OFFSHORE. A GENERAL MODEL
COMPROMISE WILL BE PREFERRED ATTM.


...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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