Prognostic Meteorological Discussion
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000
FXUS10 KWNH 270431
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1230 AM EDT WED MAY 27 2015

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

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

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


CLOSED LOW DROPPING THROUGH BRITISH COLUMBIA LATE FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 12Z UKMET IS THE MOST PROGRESSIVE WITH THIS SYSTEM FRIDAY
NIGHT.  CONSIDERING THE BLOCKING HIGH OFFSHORE HAIDA GWAII/QUEEN
CHARLOTTE ISLAND AND THE DISTANCE THIS SYSTEM IS FROM THE NORTHERN
STREAM OF THE WESTERLIES IN CENTRAL CANADA, SLOWER APPEARS BEST.
A COMPROMISE OF THE 00Z NAM/00Z GFS/12Z CANADIAN/12Z ECMWF IS
PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


SHORTWAVE MOVING ACROSS THE MIDWEST FRI NIGHT/SAT MORNING
LOW/FRONTAL PROGRESSION ACROSS THE MID-MISSISSIPPI VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE IS IN GOOD AGREEMENT HERE, OUTSIDE OF THE 00Z NAM
WHICH SHOWS A STRONG SYSTEM ALOFT AND A SLOWER FRONTAL
PROGRESSION/MORE OF A LOW ACROSS THE MIDWEST -- ITS USUAL BIAS.
PREFER A COMPROMISE OF THE 00Z GFS/12Z ECMWF/12Z CANADIAN/12Z
UKMET WITH ABOVE AVERAGE CONFIDENCE.


CYCLONE MOVING ACROSS SOUTHEAST CANADA FRIDAY
FRONT CROSSING NEW ENGLAND THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE FEATURES.


...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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