Prognostic Meteorological Discussion
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FXUS10 KWNH 241654
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1154 AM EST FRI FEB 24 2017

VALID FEB 24/1200 UTC THRU FEB 28/0000 UTC

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

12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

MID-LEVEL SHORTWAVE ACQUIRING A NEGATIVE TILT ACROSS THE LOWER
  GREAT LAKES AND NORTHEAST SAT/SAT NIGHT
COLD FRONT MOVING THROUGH THE MIDWEST LATE TODAY INTO SAT...AND
  THROUGH THE EAST COAST ON SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

ONLY THE 00Z CMC STANDS OUT FROM A STRONG CLUSTERING IN THE
ENSEMBLE SPAGHETTI HEIGHTS WITH A SLOWER/DEEPER TRACK TO THE
MID-LEVEL TROUGH. A NON 00Z CMC BLEND OF THE DETERMINISTIC
GUIDANCE AGREES WELL WITH THE ENSEMBLE CONSENSUS.


FAST MOVING MID-LEVEL SHORTWAVE TRACKING FROM THE NRN PLAINS SAT
  EVENING TO THE GREAT LAKES SUN EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

SIMILAR TO THE ABOVE SYSTEM...ONLY THE 00Z CMC STANDS OUT FROM A
STRONG CLUSTERING IN THE ENSEMBLE SPAGHETTI HEIGHTS WITH A DEEPER
TRACK TO THE MID-LEVEL TROUGH AS IT CROSSES THE GREAT LAKES
REGION. A NON 00Z CMC BLEND OF THE DETERMINISTIC GUIDANCE AGREES
WELL WITH THE ENSEMBLE CONSENSUS.


SHORTWAVE SLIDING SOUTH OFF OF THE WEST COAST TODAY/SAT AND
  REACHING THE SRN PLAINS LATE SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF OR NEAR THE 00Z EC MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE

TRENDS IN THE ENSEMBLE SPAGHETTI HEIGHTS OF 546 AND 552 DAM SHOW
THE CMC/UKMET HAVE BEEN CONSISTENTLY IN THE MINORITY OF ENSEMBLE
MEMBER CLUSTERING THROUGH SUN MORNING. WHILE THE 00Z/24 ENSEMBLE
CYCLE SHOWS BETTER CONVERGENCE...THE 00Z UKMET/CMC ARE NEARLY 180
DEGREES OUT OF PHASE WITH THE RELATIVELY GOOD AGREEMENT OF THE 12Z
NAM/12Z GFS AND 00Z ECMWF. THERE ARE MULTIPLE PARTS TO THE
SHORTWAVE EJECTING INTO THE PLAINS LATE SUN AS IT WEAKENS IN
AMPLITUDE CONSIDERABLY COMPARED TO ITS STRENGTH NEAR THE WEST
COAST. TIMING OF THE MORE DEFINED SHORTWAVE IMPULSE REACHING THE
TX PANHANDLE SUN NIGHT AND EARLY MON DIFFERS AMONG THE 12Z NAM/12Z
GFS AND 00Z ECMWF WITH THE 00Z ECMWF LAGGING OF THE 3 MODELS. THE
00Z ECMWF MEAN IS FASTER THAN THE 00Z ECMWF BUT SLOWER THAN THE
12Z GFS. THIS MIDDLE GROUND IS PREFERRED...ALTHOUGH THE 06Z GEFS
MEAN SUPPORTS THE FASTER 12Z GFS. DUE TO THE POORER THAN AVERAGE
AGREEMENT...CONFIDENCE REMAINS A BIT BELOW AVERAGE.


NEXT SHORTWAVE DROPPING OUT OF COASTAL BC TO NW US COAST SUNDAY
INTO MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF
CONFIDENCE: AVERAGE

AS THE NEXT UPPER TROUGH DESCENDS TOWARD THE PACIFIC
NORTHWEST...THE 00Z UKMET/CMC ARE STRONGER THAN A MAJORITY OF
ENSEMBLE GUIDANCE BY 00Z/27 AND THE 12Z GFS BEGINS TO PULL AHEAD
OF THE PACK. TIMING OF HEIGHT FALLS INTO THE CNTRL TO NRN PLAINS
IN THE 00Z ECMWF BETTER MATCH THE BETTER ENSEMBLE CLUSTERING
COMPARED TO THE 12Z GFS. WHILE THE 12Z NAM HAS A SIMILAR TIMING TO
THE 00Z ECMWF...THE NAM SHOWS TOWARD THE DEEPER SIDE OF THE
ENSEMBLE SPREAD AND TRENDS IN THE ENSEMBLES HAVE NOT BEEN DEEPER
BUT RATHER TOWARD THE MIDDLE...00Z ECMWF/00Z ECMWF MEAN.


www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

OTTO

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