Prognostic Meteorological Discussion
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000
FXUS10 KWNH 010649
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 AM EDT WED OCT 01 2014

VALID OCT 01/0000 UTC THRU OCT 04/1200 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: GENERAL MODEL COMPROMISE
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 MODELS SHOW SUFFICIENT LARGE
SCALE AGREEMENT SUCH THAT A GENERAL MODEL COMPROMISE CAN BE
PREFERRED ATTM TO RESOLVE ANY SMALLER SCALE DIFFS.


...POWERFUL TROUGH/CLOSED LOW EXPECTED TO DEVELOP OVER THE GREAT
LAKES/MIDWEST...
...SHEARING SOUTHERN STREAM ENERGY OVER THE SOUTHERN PLAINS...

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

THE MODELS INDICATE A VERY STRONG NORTHERN STREAM TROUGH DIGGING
INTO THE NRN PLAINS AND UPR MIDWEST THURS AND FRI WHICH WILL
ASSUME SOME NEG TILT AND SHOULD 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 AND LWR MS VLY BEFORE GRADUALLY BE ABSORBED BY THE MORE
DOMINANT NRN STREAM ENERGY.

ACROSS THE NRN PLAINS AND UPR MIDWEST...THE TREND HAS BEEN FOR A
STRONGER NRN STREAM TROUGH TO DEVELOP...WITH A CLOSED LOW THAT
SHOULD DIVE SEWD ACROSS THE MIDWEST AND TWD THE OH VLY BY
SAT...AND A SEPARATE CLOSED LOW DEVELOPING BACK OVER THE UPR GRT
LAKES REGION. THE 00Z GFS/00Z UKMET AND 00Z GEM ARE TRENDING TWD
THE ECMWF SOLN REGARDING DEPTH. THE 00Z ECMWF DID TREND A BIT
SLOWER WITH ITS MASS FIELD EVOLUTION AND CLUSTERS BEST WITH THE
00Z GFS OVERALL. THE 00Z NAM SUGGESTS THE FOCUS OF ANY CLOSED LOW
FEATURE WILL BE OVER THE GRT LAKES REGION...WITH ANYTHING FARTHER
SOUTH BEING WEAK AND ILL-DEFINED ASIDE FROM THE LARGER SCALE
TROUGH AXIS. REGARDING THE SRN STREAM TROUGH...ALL OF THE MODELS
DEPICT A PROGRESSIVE SHORTWAVE TROUGH THAT WILL DIG THROUGH THE
CNTRL/SRN ROCKIES AND QUICKLY OUT ACROSS THE SRN PLAINS AND LWR MS
VLY BEFORE BECOMING SHEARED APART AND ABSORBED BY THE MORE
POWERFUL NRN STREAM HEIGHT FALLS. BASED ON THE COLLECTIVE TRENDS
SEEN OVER THE LAST DAY OR SO...IT WOULD APPEAR THAT A MORE
AGGRESSIVE SOLN COMPARABLE TO THE ECMWF IS BECOMING MORE LIKELY.
BASED ON BETTER MODEL CLUSTERING...A BLEND OF THE GFS AND ECMWF
WILL BE PREFERRED.


...UPPER TROUGH/CLOSED LOW IMPACTING THE NORTHERN MID-ATLANTIC AND
SOUTHERN NEW ENGLAND...

PREFERENCE: NON-ECMWF CONSENSUS
CONFIDENCE: AVERAGE

THE MODELS TAKE THE SLOW MOVING CLOSED LOW OVER THE NRN
MID-ATLANTIC REGION OFF TO THE EAST INTO SRN NEW ENGLAND ON WED
AND SLOWLY OFFSHORE THROUGH FRI. THE MODELS OVERALL HAVE TRENDED
MORE AGGRESSIVE WITH OFFSHORE SFC LOW DEVELOPMENT AND HAVE A
NOTABLE INVERTED TROUGH THAT EXTENDS BACK WWD TWD AREAS JUST SOUTH
OF SRN NEW ENGLAND AND NEAR THE BENCHMARK WED NIGHT AND THURS. BY
FRI AND SAT...THE 00Z ECMWF HANGS ITS CLOSED LOW FARTHER BACK TO
THE WEST...WITH THE 00Z NAM/00Z GFS/00Z GEM AND 00Z UKMET ALL
QUICKER TO SEND THE ENERGY FARTHER OFFSHORE AND AWAY FROM NEW
ENGLAND. THE ECMWF HAS TRENDED JUST A TAD QUICKER TO EJECT THE
CLOSED LOW AWAY FROM NEW ENGLAND BY SAT...BUT STILL IS WEST OF THE
GLOBAL MODEL CONSENSUS FRI AND SAT. WILL FAVOR A NON-ECMWF
CONSENSUS FOR FRI AND SAT AS THE SYS SHOULD BEGIN TO ADVANCE
EASTWARD IN LIGHT OF THE STRONG UPSTREAM HEIGHT FALLS APPROACHING
THE EAST COAST.


...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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