Prognostic Meteorological Discussion
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055
FXUS10 KWNH 270411
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1210 AM EDT TUE SEP 27 2016

VALID SEP 27/0000 UTC THRU SEP 30/1200 UTC

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

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


DEEP CYCLONE DROPPING INTO THE NRN CUMBERLAND PLATEAU THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/UKMET/NAM COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

CONVERGENCE AMONGST THE GUIDANCE HAS BEEN SEEN OVER THEIR PAST DAY
OF RUNS.  THE 12Z CANADIAN NOW LIES ON THE EASTERN SIDE OF THE
GUIDANCE.  THE 12Z ECMWF LIES ON THE WEST SIDE OF THE GUIDANCE
LATE THURSDAY INTO EARLY FRIDAY.  A LOOK AT THE UPWARD VERTICAL
MOTION FIELDS SHOW A COUPLE BULL`S EYES WHICH APPEAR TO YANK THE
SYSTEM SLIGHTLY NORTHWEST AND LEAD TO THE SLIGHT DIVERGENCE FROM
THE CONSENSUS.  SINCE THIS IS A KNOWN PROBLEM WITH THE ECMWF,
PREFER A COMPROMISE OF THE 12Z UKMET/00Z NAM/00Z GFS WITH SLIGHTLY
ABOVE AVERAGE CONFIDENCE.


UPPER LOW WEAKENING NORTHWARD INTO SRN CA AND THE GREAT BASIN
COLD FRONT ENTERING THE PACIFIC NORTHWEST TONIGHT AND MT LATE TUE
UPPER TROUGH AMPLIFYING OFFSHORE THE PACIFIC NORTHWEST WED/THU
WEAKENING UPPER LEVEL LOW NEAR FL TUESDAY
SHORTWAVE MOVING BY MAINE/ATLANTIC CANADA TUE/TUE NIGHT
LOW MOVING OFFSHORE NEW ENGLAND TUE NIGHT/WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE FEATURES.  A
COMPROMISE OF THE AVAILABLE GUIDANCE IS PREFERRED WITH ABOVE
AVERAGE CONFIDENCE.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

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

ROTH
$$





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