Prognostic Meteorological Discussion
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000
FXUS10 KWNH 230424
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1223 AM EDT SUN APR 23 2017

VALID APR 23/0000 UTC THRU APR 26/1200 UTC

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

00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
IN THE NORTHWEST CARIBBEAN, THE GUIDANCE SHOWS A REASONABLE
PORTRAYAL OF THE BROAD LOW SOUTHWEST OF THE ISLE OF PINES/YOUTH.
THE WEAKENING CONVECTIVE LOW MOVING EAST OF HAVANA DOES NOT SEEM
TO BE PICKED UP BY THE 00Z GFS PRESSURE, WIND, OR QPF PATTERN,
WHILE THE 00Z NAM APPEARS TO HAVE A BETTER HANDLE ON THIS FEATURE
IN ITS BOUNDARY LAYER WIND FIELD.


SYSTEM APPROACHING THE PACIFIC NORTHWEST TUE NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THERE ARE SOME SOME DETAIL ISSUES REGARDING THE DEPTH OF AN
INCOMING UPPER LEVEL SHORTWAVE WHICH CAN RESOLVED BY TAKING A
COMPROMISE OF THE AVAILABLE GUIDANCE -- SIMILAR TO THE PARALLEL
VERSION OF THE NATIONAL BLEND OF MODELS -- WHICH IS PREFERRED WITH
ABOVE AVERAGE CONFIDENCE.


TROUGH EMERGING INTO THE PLAINS ON TUE NIGHT/WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF/CANADIAN COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM APPEARS TOO SHARP/DEEP ALOFT WITH THIS SYSTEM (ITS
USUAL BIAS), WHILE THE 12Z UKMET IS A SLOW OUTLIER.  WHILE THE
SYSTEM IS SLOWLY AMPLIFYING, IT IS STILL EMBEDDED WITHIN A FLOW
WITH A LONG WAVELENGTH, WHICH WOULD ARGUE AGAINST THE SLOWER
UKMET.  A COMPROMISE OF THE 00Z GFS/12Z CANADIAN/12Z ECMWF IS
PREFERRED WITH ABOVE AVERAGE CONFIDENCE.


SYSTEM MOVING UP THE EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF/UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 12Z CANADIAN WAS TOO QUICK TO MOVE THIS SYSTEM UP THE COAST,
WHICH CAN HAPPEN WITH SYSTEMS WITH EMBEDDED CONVECTION, WHILE THE
00Z NAM WAS TOO SLOW IN ITS RECURVATURE, ONE OF ITS OLD BIASES.
THE 00Z GFS/12Z ECMWF/12Z UKMET BEST FIT THE ENSEMBLE MEAN
SOLUTIONS, SO A COMPROMISE OF THE THREE IS PREFERRED FOR MASS
FIELDS.  FROM A MESOSCALE CONVECTIVE STANDPOINT, NONE OF THE HIGH
RESOLUTION GUIDANCE IS HANDLING THE PRECIPITATION PATTERN WITH ANY
DEGREE OF PRECISION AT THE PRESENT TIME.  SEE THE DAY 1 QPF
DISCUSSION ISSUED BY 07Z FOR DETAILS CONCERNING THE DAY 1 RAINFALL
FORECAST ACROSS FL.


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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