Prognostic Meteorological Discussion
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000
FXUS10 KWNH 241613
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1212 PM EDT TUE MAY 24 2016

VALID MAY 24/1200 UTC THRU MAY 28/0000 UTC

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

12Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO DEGRADE THEIR SHORT
RANGE FORECASTS.


SYSTEM DIVING INTO THE PACIFIC NORTHWEST FRIDAY
CLOSED LOW LIFTING INTO THE NORTHEAST TUE/WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS REASONABLE AGREEMENT WITH THESE SYSTEMS.  TO
DEAL WITH LINGERING DETAIL ISSUES, PREFER A COMPROMISE OF THE
AVAILABLE DETERMINISTIC GUIDANCE WITH ABOVE AVERAGE CONFIDENCE.


SOUTHWEST TO CENTRAL PLAINS UPPER LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z UKMET WAS ON THE NORTH AND DEEP SIDE WITH THIS OVERALL
SYSTEM PER THE MOST RECENT DETERMINISTIC AND 00Z GLOBAL ENSEMBLE
GUIDANCE.  PREFER A COMPROMISE OF THE 12Z GFS/12Z NAM/00Z
CANADIAN/00Z ECMWF WITH ABOVE AVERAGE CONFIDENCE.


PAIR OF UPPER LOWS ALONG CENTRAL US/CANADIAN BORDER
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z UKMET IS A DEEP OUTLIER WITH THE FIRST SYSTEM, WHICH IS
MOST NOTICEABLE AT 700 HPA.  OTHERWISE, IT BECOMES TOO
RETROGRESSIVE THE SECOND/WESTERN SYSTEM, A BIAS SOMETIMES
DISPLAYED IN ALL THE MODEL GUIDANCE.  PREFER A COMPROMISE OF THE
12Z GFS/12Z NAM/00Z CANADIAN/00Z ECMWF WITH ABOVE AVERAGE
CONFIDENCE.


UPPER LOW DRIFTING ABOUT THE FL STRAITS
& ITS CONVECTIVE SURFACE REFLECTION
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CANADIAN/GFS/ECMWF COMPROMISE
CONFIDENCE: AVERAGE

MOST OF THE GUIDANCE DEVELOPS AN INVERTED TROUGH NEAR AND NORTH OF
THE BAHAMAS IN A DIVERGENT AREA ALOFT NORTH OF AN UPPER LOW, A
CONVECTIVELY FAVORABLE ENVIRONMENT.  WITH THE UPPER LOW ITSELF,
THE GUIDANCE SHOWS GOOD AGREEMENT, THOUGH THE 12Z NAM IS A BIT
DEEP -- ITS USUAL BIAS AT THIS TIME RANGE.  BOTH THE 12Z NAM AND
00Z CANADIAN DEVELOP A SURFACE LOW WITH A CLOSED ISOBAR, THOUGH
THE 12Z NAM IS MORE RETROGRESSIVE -- A COMMON MODEL BIAS.  AT
LEAST ONE-THIRD OF THE 00Z GLOBAL ENSEMBLE MEMBERS DEPICT A LOW
NORTH OF THE BAHAMAS FRIDAY MORNING, IN A POSITION WHICH BEST
MATCHES THE 00Z CANADIAN.  IN CASE THE CANADIAN IS TOO STRONG,
PREFER A COMPROMISE OF THE 00Z CANADIAN, 12Z GFS, AND 00Z ECMWF
HERE WITH 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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