Prognostic Meteorological Discussion
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000
FXUS10 KWNH 241846
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
145 PM 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 MODEL EVALUATION INCLUDING FINAL 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: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

ADJUSTMENTS BY THE 12Z CMC TOWARD THE REMAINING MODEL CONSENSUS
RELATIVE TO ITS 00Z CYCLE ARE ENOUGH THAT A GENERAL MODEL
COMPROMISE CAN NOW BE PREFERRED FOR THIS SYSTEM GIVEN GOOD
AGREEMENT ALL AROUND.


FAST MOVING MID-LEVEL SHORTWAVE TRACKING FROM THE NRN PLAINS SAT
  EVENING TO THE GREAT LAKES SUN EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

SIMILAR TO THE ABOVE SYSTEM...THE 12Z CMC MADE FLATTER ADJUSTMENTS
RELATIVE TO ITS 00Z CYCLE SUCH THAT ONLY MINOR AMPLITUDE
DIFFERENCES REMAIN WITH THE 12Z SUITE OF DETERMINISTIC GUIDANCE. A
GENERAL MODEL BLEND IS RECOMMENDED TO SMOOTH OUT THESE SMALLER
SCALE DIFFERENCES GIVEN THEIR AGREEMENT TO 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/12Z ECMWF OR NEAR THE 00Z EC MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE

TRENDS IN THE UKMET/CMC CONTINUE TO CONVERGE TOWARD THE BETTER
ENSEMBLE CLUSTERING IN THE 546 AND 552 DAM HEIGHT CONTOURS AT 500
MB VALID THROUGH SUN MORNING. THE 00Z ENSEMBLE CYCLE SHOWS BETTER
CONVERGENCE COMPARED TO PREVIOUS CYCLES BUT REMAIN SIGNIFICANTLY
DISPERSED. 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 FASTER 12Z NAM/12Z GFS/12Z UKMET AND
SLOWER 12Z ECMWF/CMC. THE 00Z ECMWF MEAN IS FASTER THAN THE
12Z/00Z ECMWF BUT SLOWER THAN THE 12Z GFS. THIS MIDDLE GROUND IS
PREFERRED...ALTHOUGH THE 12Z 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: 12Z ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE

AS THE NEXT UPPER TROUGH DESCENDS TOWARD THE PACIFIC
NORTHWEST...THE 12Z GFS BEGINS TO PULL AHEAD OF THE
DETERMINISTIC/ENSEMBLE CLUSTERING. TIMING OF HEIGHT FALLS INTO THE
CNTRL TO NRN PLAINS IN THE 12Z ECMWF/UKMET IS A BETTER MATCH THE
BETTER ENSEMBLE CLUSTERING COMPARED TO THE 12Z GFS. THE 12Z UKMET
JOINING THE ECMWF INCREASES CONFIDENCE IN THEIR SOLUTIONS. WHILE
THE 12Z NAM HAS A SIMILAR TIMING TO THE ECMWF/UKMET...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...NEAR THE 12Z ECMWF/12Z UKMET/00Z ECMWF MEAN.


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

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

OTTO

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