Prognostic Meteorological Discussion
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FXUS10 KWNH 151703
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1202 PM EST SUN JAN 15 2017

VALID JAN 15/1200 UTC THRU JAN 19/0000 UTC

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

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


*CLOSED LOW REACHING THE SOUTHERN PLAINS MON MORNING
SURFACE LOW TRACKING FROM THE SOUTHERN PLAINS TO THE UPPER MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/12Z NAM BLEND
CONFIDENCE: AVERAGE

THE 12Z GFS IS THE FASTEST OF THE LATEST DETERMINISTIC MODELS WITH
THE OPEN WAVE AS IT REACHES THE UPPER MIDWEST 12Z/17 AND IS TOWARD
THE FASTER EDGE OF THE ENSEMBLE SPREAD. MEANWHILE...THE 00Z CMC
SHOWS UP AS A SLOW OUTLIER WITH THIS FEATURE...FOLLOWED BY THE 00Z
UKMET TOWARD THE SLOWER EDGE OF THE ENSEMBLE SPREAD. THE ENSEMBLES
SHOW MORE POTENTIAL TO BE FASTER THAN SLOWER...BUT STAYING TOWARD
THE MIDDLE OF THE RATHER UNSTABLE RUN TO RUN CONTINUITY IS
PREFERRED AT THIS TIME WHICH IS NEAR THE 12Z NAM AND 00Z ECMWF. IF
MORE MORE SUPPORT IS GAINED FOR A FASTER TRACK LIKE THE GFS WHEN
THE 12Z ECMWF/UKMET/CMC ARRIVE...THE FINAL PREFERENCE MAY REFLECT
THIS FASTER OUTPUT.


SHORTWAVE CROSSING THE NRN ROCKIES/NRN PLAINS SUN NIGHT/MON
INTERACTION WITH THE SHORTWAVE TRACKING FROM THE SRN PLAINS INTO
  THE MIDWEST MON/TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE 12Z NAM REMAINS BETWEEN THE DEEPER 12Z GFS AND SHALLOWER 00Z
ECMWF BY 12Z/17 BUT ENDS UP TOWARD THE FAST SIDE OF THE LATEST
GUIDANCE BY 12Z/18. THE ECMWF HAS BEEN FLIP FLOPPING BETWEEN
SLOWER/DEEPER AND FASTER/WEAKER WITH THIS FEATURE OVER ITS PAST 4
CYCLES...AND MAY ADJUST AGAIN FOR ITS 12Z/15 CYCLE. THE PREFERENCE
IS TO BE IN THE MIDDLE OF THE FLIP FLOPPING WHICH HAPPENS TO BE IN
BETWEEN THE 12Z GFS AND FASTER 12Z NAM. THIS IF BETWEEN THE 00Z
ECMWF/UKMET. CONFIDENCE IS LOWER THAN AVERAGE GIVEN THE POOR RUN
TO RUN CONSISTENCY IN ALL OF THE MODELS AND THE COMPLEX
INTERACTION OF MULTIPLE VORTICITY MAXIMA.


SOUTHWESTERN U.S. AND NWRN MEXICO UPPER TROUGH THROUGH TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 06Z GEFS/00Z ECMWF MEAN
CONFIDENCE: AVERAGE

THE LATEST GEFS/ECMWF MEANS SHOW A PREFERRED MIDDLE GROUND AMONG
THE LATEST DETERMINISTIC MODELS. BY 12Z/18...THE FORECAST IS FOR
AN ELONGATED CLOSED LOW STRETCHING FROM THE GULF OF CA TO THE
TX/OK PANHANDLES...WITH QUESTIONS AS TO HOW MUCH ENERGY IS IN THE
NRN PORTION OF THE TROUGH AND THE SRN PORTION. THE LATEST
DETERMINISTIC MODELS SHOW VARYING IDEAS...BUT NONE SEEM TO SHOW AN
APPROPRIATE MIDDLE GROUND...INSTEAD SHOWING MORE ENERGY UP NORTH
OR SOUTH. WHILE THE 00Z CMC IS A DECENT MIDDLE GROUND...IT APPEARS
TO BE TOO LARGE GIVEN THE LATEST ENSEMBLE SPAGHETTI HEIGHT
CONTOURS. THEREFORE...A BLEND OF THE 06Z GEFS AND 00Z ECMWF MEANS
IS PREFERRED.


SHORTWAVES IN FAST FLOW ACROSS THE PACIFIC NORTHWEST MON/TUE
AMPLIFYING TROUGH OFF OF THE WEST COAST WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW NORMAL

THERE IS A LOW CONFIDENCE IN THE INDIVIDUAL SHORTWAVE DETAILS
WITHIN A RATHER ROBUST ONSHORE FLOW INTO BRITISH COLUMBIA AND THE
PACIFIC NORTHWEST. A GENERAL BLEND IS PREFERRED HERE TO IRON OUT
SMALLER SCALE DETAILS. BY 00Z/19...THERE IS VERY GOOD AGREEMENT
FOR AN INCREASED AMPLITUDE MID-UPPER LEVEL TROUGH OFF OF THE WEST
COAST...WITH RELATIVELY MINOR DETERMINISTIC DIFFERENCES. THE
ENSEMBLES SHOW LITTLE ROOM FOR SPEED DIFFERENCES...BUT MODEST
AMPLITUDE DIFFERENCES. THE 12Z GFS AND 00Z ECMWF BEST REPRESENT
THE MIDDLE OF THIS SPREAD.

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

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


OTTO

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