Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12
000
FXUS10 KWNH 241828
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 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 MODEL EVALUATION WITH PREFERENCES/CONFIDENCE LEVELS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO DEGRADE THEIR SHORT
RANGE FORECASTS.


SOUTHWEST TO CENTRAL PLAINS UPPER LOW
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.


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

THE 00Z/12Z UKMET WERE DEEP OUTLIERS 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: NON-NAM 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
12Z 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/12Z CANADIAN RUNS.  IN CASE THE CANADIAN IS TOO
STRONG, PREFER A COMPROMISE OF THE 12Z CANADIAN, 12Z GFS, 12Z
UKMET, AND 12Z 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
$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.