Prognostic Meteorological Discussion
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000
FXUS10 KWNH 300441
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1239 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 AND GFS


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

PREFERENCE: BLEND OF THE 12Z GEM AND 12Z 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 12Z UKMET WAS SEEN AS BEING
A LITTLE RIGHT OF THE GLOBAL MODEL CONSENSUS AND A LITTLE SLOWER.
THE 00Z GFS IS A LITTLE LEFT OF THE SAME CONSENSUS. THE 00Z NAM
EVENTUALLY BECOMES A BIT LEFT OF THE LARGER CLUSTERING BY WED AS
THE ENERGY LIFTS INTO SRN CANADA. THE 12Z GEM AND 12Z ECMWF SPLIT
THE DIFF AND 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 12Z 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 AND 12Z UKMET
ARE NOTABLY STRONGER WITH THEIR HEIGHT FALLS. THE 12Z GEM KEEPS
THE STRONGEST OF ITS HEIGHT FALLS CONFINED TO SRN CANADA. THE 00Z
GFS AND 12Z ECMWF ARE FARTHER SOUTH WITH THEIR HEIGHT FALLS BY
COMPARISON...BUT JUST NOT QUITE AS AMPLIFIED AS THE NAM AND UKMET.
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 BE PREFERRED ATTM WITH THE MORE
DOMINANT NRN STREAM ENERGY.

REGARDING THE SRN STREAM TROUGH...THE 12Z GEM AND TO AN EXTENT THE
12Z UKMET WERE THE MOST AGGRESSIVE WITH THIS SRN STREAM TROUGH AND
THE GEM SUPPORTS A CLOSED LOW DEVELOPING OUT OF IT. THE 00Z
GFS/00Z NAM AND 12Z ECMWF ARE NOT AS AMPLIFIED. THE 12Z ECMWF
ACTUALLY THROUGH DAY 2 IS THE MOST PROGRESSIVE. 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...ALTHOUGH THE GFS
IS MORE PREFERRED THROUGH DAY 2...AND THEN BOTH GFS AND ECMWF ON
DAY 3.


...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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