Prognostic Meteorological Discussion
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FXUS10 KWNH 101839
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
139 PM EST SUN DEC 10 2017

VALID DEC 10/1200 UTC THRU DEC 14/0000 UTC

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

12Z MODEL PREFERENCES WITH CONFIDENCE INTERVALS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GFS/NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


CLOSED LOW STUCK ACROSS NORTHWEST MEXICO MONDAY-WEDNESDAY
DEEP LAYER CYCLONE OVER NEW ENGLAND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE SYSTEMS.  A
COMPROMISE OF THE 12Z GFS, 12Z NAM, 12Z ECMWF, 12Z UKMET, AND 12Z
CANADIAN IS PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


CYCLONE/SHORTWAVE DIVING INTO THE MIDWEST LATE WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: WEAKER THAN 12Z ECMWF; CONFIDENCE AVERAGE

THERE ARE DETAIL ISSUES AT 500 HPA WITH THE SHORTWAVES ROUNDING
THE WEST SIDE OF THE TROUGH.  THE 12Z ECMWF AND 12Z UKMET ARE
LIKELY TOO STRONG CONSIDERING THE BREADTH OF THE UPPER TROUGH
WHICH SHOULD ALLOW MINIMAL AMPLITUDE.  THESE ISSUES MANIFEST
THEMSELVES A BIT MORE IN THE LOW LEVELS, WITH THE 12Z UKMET THE
FARTHEST NORTH AND THE CANADIAN THE FARTHEST SOUTHWEST.  BOTH LIE
OUTSIDE THE 00Z ENSEMBLE LOW SPREAD SO ARE NOT CONSIDERED VIABLE.
A COMPROMISE OF THE 12Z NAM, 12Z GFS, AND 12Z ECMWF SHOULD DEAL
WITH THE ECMWF`S DEPTH ISSUE ALOFT EFFECTIVELY AND REMAIN WITHIN
THE ENSEMBLE SPREAD AT THE SURFACE.  CONFIDENCE IS AVERAGE IN THIS
CHOICE.


THE NEXT COMPLETE MODEL DIAGNOSTIC DISCUSSION (PMDHMD) WILL BE
ISSUED BY 1645Z MONDAY.

ROTH


PREVIOUS MODEL TRENDS AT www.wpc.ncep.noaa.gov/html/model2.shtml

PREVIOUS 500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

$$
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