Prognostic Meteorological Discussion
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000
FXUS10 KWNH 250645
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 AM EDT SUN JUN 25 2017

VALID JUN 25/0000 UTC THRU JUN 28/1200 UTC

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

00Z MODEL EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS


DEEP LAYERED CYCLONE MOVING THROUGH WESTERN CANADA
WEAK UPPER DISTURBANCE MOVING INTO NORTHERN CA LATE MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: COMPROMISE OF GUIDANCE; CONFIDENCE ABOVE AVERAGE

WHILE THE 00Z UKMET/00Z CANADIAN APPEARS SLIGHTLY FARTHER SOUTH
WITH THE MAIN MID-LEVEL VORTEX VERY EARLY WEDNESDAY, THE SURFACE
PRESSURE PATTERN IS QUITE CLOSE TO THE OTHER GUIDANCE.
DIFFERENCES IN THE DEPTH OF THE UPPER TROUGH ACROSS THE
INTERMOUNTAIN WEST AND A LEADING SHORTWAVE MOVING INTO THE MIDWEST
ARE WITHIN THE NOISE LEVEL OF THE GLOBAL ENSEMBLE GUIDANCE.  A
COMPROMISE OF THE 00Z GFS, 00Z NAM, 00Z UKMET, 00Z ECMWF, AND 00Z
CANADIAN IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


MID-LEVEL WEAKNESS ACROSS THE WESTERN GULF OF MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CANADIAN/UKMET; CONFIDENCE AVERAGE

THE 00Z ECMWF AND ITS ENSEMBLE MEAN ARE MORE RETROGRESSIVE WITH
THIS WEAK SYSTEM THAN THE OTHER GUIDANCE, A BIAS WHICH WAS
RECENTLY SEEN WITH THE UPPER LOW AHEAD OF TROPICAL CYCLONE CINDY.
THERE`S NO PARTICULAR REASON TO BELIEVE EXTRA WESTWARD MOTION
WOULD OCCUR BY WEDNESDAY MORNING AS THE WESTERLIES TO THE NORTH
ARE ZONAL AND THE RIDGES TO THE WEST IN NORTHWEST MEXICO AND
ACROSS THE FL STRAITS ARE FAIRLY EVEN IN STRENGTH WEDNESDAY
MORNING.  PREFER A COMPROMISE OF THE GUIDANCE CLOSEST TO THE 00Z
CANADIAN/00Z UKMET WITH AVERAGE CONFIDENCE.


UPPER TROUGH MOVING THROUGH THE GREAT LAKES/EAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: COMPROMISE OF GUIDANCE; CONFIDENCE ABOVE AVERAGE

WHILE THERE ARE SLIGHT TIMING AND DEPTH ISSUES WITH THIS SYSTEM,
THEY ARE WELL WITHIN THE GLOBAL ENSEMBLE SPREAD AND MAKE MINIMAL
IMPACT ON THE PRESSURE AND 700 HPA HEIGHT FIELD.  A COMPROMISE OF
THE 00Z GFS, 00Z NAM, 00Z UKMET, 00Z ECMWF, AND 00Z CANADIAN IS
PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

ROTH
$$





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