Prognostic Meteorological Discussion
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000
FXUS10 KWNH 260641
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 AM EDT MON SEP 26 2016

VALID SEP 26/0000 UTC THRU SEP 29/1200 UTC

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

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


DEEP CYCLONE DROPPING TOWARDS OH VALLEY
FRONTAL WAVE MOVING OFFSHORE EASTERN SEABOARD
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CLOSEST TO THE UKMET
CONFIDENCE: NO BETTER THAN AVERAGE

THERE HAS BEEN SOME CONVERGENCE SEEN IN THE GUIDANCE WITH THE MAIN
UPPER LOW SINCE THIS TIME YESTERDAY, WITH THE GFS/CANADIAN/UKMET
TRENDING SOUTHWARD AND THE ECMWF TRENDING NORTHWARD.  A BUILDING
UPSTREAM RIDGE IN THE PLAINS COULD ALLOW FOR A MORE SOUTHERN
SOLUTION, BEST SEEN IN THE 00Z NAM -- UNFORTUNATELY THIS CAN BE AN
OCCASIONAL BIAS OF THE NAM.  SINCE THERE HAS BEEN CONVERGENCE SEEN
IN THE GUIDANCE, PREFER A GENERAL MODEL COMPROMISE HERE, WHICH IS
CLOSEST TO THE 00Z UKMET.  CONFIDENCE REMAINS NO BETTER THAN
AVERAGE SINCE THE GUIDANCE REMAINS SOMEWHAT UNSTABLE.


SHORTWAVE MOVING BY MAINE/ATLANTIC CANADA
LOW MOVING OFFSHORE NEW ENGLAND WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF/UKMET COMPROMISE
CONFIDENCE: NO BETTER THAN AVERAGE

THE UKMET/GFS GUIDANCE ARE WEAKER OR MORE NORTHERN VERSIONS OF THE
00Z ECMWF IN TAKING ENERGY NORTH OF MAINE THROUGH ATLANTIC CANADA.
 FOR THE UKMET, THIS WAS A MARKED CHANGE FROM CONTINUITY.  FOR THE
TIME BEING, PREFER A COMPROMISE OF THE AVAILABLE CONSENSUS (00Z
RUNS OF THE GFS/ECMWF/UKMET) WITH CONFIDENCE NO BETTER THAN
AVERAGE.


UPPER TROUGH AMPLIFYING OFFSHORE THE NORTHWEST WED
UPPER LOW SHEARING NORTHWARD INTO THE GREAT BASIN
SYSTEM CLIPPING THE PACIFIC NORTHWEST MON NIGHT
WEAKENING UPPER TROUGH NEAR FL MONDAY AND TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE SYSTEMS.  PREFER A
COMPROMISE OF THE AVAILABLE GUIDANCE TO DEAL WITH DETAIL ISSUES,
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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