Prognostic Meteorological Discussion
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000
FXUS10 KWNH 271626
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1224 PM EDT MON APR 27 2015

VALID APR 27/1200 UTC THRU MAY 01/0000 UTC

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

12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DISCUSSION OF AN ISSUE WITH CANADIAN ENERGY PARTICIPATING IN THE
EVOLUTION OF THE SOUTHEAST CLOSED LOW WILL BE DISCUSSED IN ITS
SECTION BELOW.


ENERGY NEAR CALIFORNIA THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/GFS COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z UKMET WAS STRONGEST WITH THIS SYSTEM WHILE THE 12Z NAM WAS
THE WEAKEST.  THE 00Z ECMWF/12Z GFS ARE A NICE COMPROMISE OF THE
AVAILABLE GUIDANCE, WITH THIS SOLUTION PREFERRED WITH ABOVE
AVERAGE CONFIDENCE.


SHORTWAVE MOVING ALONG WESTERN US/CAN BORDER WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-ECMWF COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z ECMWF BECOMES A FAST OUTLIER WITH THIS SYSTEM, WHICH MAY
ALSO INFLUENCE ITS QUICKER SOLUTION ALOFT ACROSS THE SOUTHEAST ON
THURSDAY.  PREFER A COMPROMISE OF THE 00Z CANADIAN/00Z UKMET/12Z
GFS/12Z NAM WITH SLIGHTLY ABOVE AVERAGE.


DEEP CYCLONE FORMING ACROSS THE SOUTHEAST THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CLOSEST TO THE 12Z GFS
CONFIDENCE: AVERAGE

THE GUIDANCE IS HANDLING THIS SYSTEM DIFFERENTLY.  ONE OF THE
ISSUES INVOLVES THE INITIAL SHORTWAVE IN WESTERN CANADA, WITH THE
12Z GFS APPEARS TO BE HANDLING BETTER THAN THE 00Z ECMWF.  ANOTHER
ISSUE INVOLVES A STRONGER SHORTWAVE MOVING OVER THE TOP OF THE
DOWNSTREAM RIDGE, WHICH THE 00Z CANADIAN IS GUILTY OF.  A THIRD
ISSUE INVOLVES CONVECTIVE FEEDBACK CONTAMINATING THE 00Z ECMWF 700
HPA HEIGHT FIELD (LIKELY TOO STRONG NEAR THE CAROLINA/VA COAST).
IN REGARDS TO THE SURFACE LOW TRACK, THE 00Z GLOBAL ENSEMBLE
GUIDANCE RULED OUT THE 00Z CANADIAN/00Z UKMET SOLUTIONS.  A
COMPROMISE OF THE 00Z ECMWF/12Z NAM/12Z GFS BEST RESEMBLES THE 12Z
GFS, WHICH IS PREFERRED WITH AVERAGE CONFIDENCE.


ENERGY LEAVING NEW ENGLAND WEDNESDAY/THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CANADIAN COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z CANADIAN SHOWS STRONGER ENERGY STUCK ACROSS ATLANTIC
CANADA OVER THE TOP OF A SOUTHERN STREAM RIDGE -- NORMALLY A VERY
UNSTABLE POSITION FOR CLOSED LOWS DUE TO NEARBY SUPERGEOSTROPIC
FLOW THAT NORMALLY MOVES SYSTEMS ALONG.  PREFER A NON-CANADIAN
COMPROMISE HERE 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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