Prognostic Meteorological Discussion
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FXUS10 KWNH 010423
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1222 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 AND GFS


...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/12Z ECMWF AND 12Z UKMET
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 AND 12Z UKMET ARE TRENDING TWD THE 12Z
ECMWF SOLN WITH REGARDING DEPTH...ALTHOUGH THE 12Z ECMWF IS
NOTABLY FASTER TO SPREAD STRONG HEIGHT FALLS INTO THE OH VLY. THE
00Z NAM AND 12Z GEM SUGGEST 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. THE ECMWF MAY BE
TOO FAST WITH ITS HEIGHT FALLS...AND SO TO MITIGATE THIS...WILL
PREFER A GFS/ECMWF AND UKMET BLEND.


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

PREFERENCE: BLEND OF THE 12Z GEM AND 12Z ECENS MEAN
CONFIDENCE: SLIGHTLY BELOW 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 12Z ECMWF HANGS ITS CLOSED LOW FARTHER BACK TO
THE WEST...WITH THE 00Z NAM/00Z GFS AND 12Z UKMET ALL QUICKER TO
SEND THE ENERGY FARTHER OFFSHORE AND AWAY FROM NEW ENGLAND. THE
12Z GEM SPLITS THE DIFF. THE LATEST GEFS MEAN SUPPORTS THE
RELATIVELY MORE CONSENSUS CAMP...WITH THE ECENS MEAN A LITTLE EAST
OF THE DETERMINISTIC ECMWF AND CLOSE TO THE GEM SOLN. AS A
COMPROMISE...WILL PREFER A BLEND OF THE GEM AND ECENS MEAN.


...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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