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
000
FXUS10 KWNH 221838
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 PM EDT TUE JUL 22 2014

VALID JUL 22/1200 UTC THRU JUL 26/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING FINAL PREFERENCES


MID LEVEL LOW SLOWLY RETROGRADING OVER THE GULF COAST STATES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z NAM BLEND
CONFIDENCE: ABOVE AVERAGE

THE MODELS AGREE ON WEAKENING THIS FEATURE ALONG WITH INCREASING
SHEARING AS THE LOW SLOWLY RETROGRADES WWD ALONG THE GULF COAST.
THE 00Z UKMET/CMC APPEAR TOO WEAK WITH THE 500 MB LOW COMPARED TO
THIS MORNINGS 12Z RAOB DATA...AND ARE ALSO THE WEAKEST WITH THIS
LOW AS IT TRACKS WWD INTO SOUTH TEXAS...BUT THEIR 12Z CYCLES
APPEAR MUCH BETTER. ON THE OTHER SIDE...THE 12Z NAM WHILE
INITIALIZED WELL...IS THE SLOWEST OF THE DETERMINISTIC MODEL
SUITE. THE 12Z ECMWF COMPARES FAVORABLY TO THE REMAINING NON NAM
CONSENSUS HAVING MADE LITTLE CHANGE FROM ITS 00Z RUN.
THEREFORE...A NON 12Z NAM CONSENSUS OF MODELS IS PREFERRED DUE TO
THEIR PLACEMENT IN THE MIDDLE OF THE DETERMINISTIC/ENSEMBLE SPREAD.


CLOSED LOW PASSING THROUGH THE NORTHWEST WED/THU
SURFACE LOW PRESSURE DEVELOPING IN THE LEE OF THE NORTHERN ROCKIES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM / 12Z ECMWF / 12Z UKMET BLEND
CONFIDENCE: AVERAGE

THE 12Z GFS IS SOUTH OF THE REMAINING DETERMINISTIC/ENSEMBLE
CONSENSUS REGARDING THE CLOSED LOW AS IT MOVES THROUGH ALBERTA
INTO SASKATCHEWAN...WITH THE 12Z GFS ALSO SHOWING UP FASTER WITH
THE PROGRESSION OF THE CLOSED LOW. THESE DIFFERENCES BEGIN TO
APPEAR AROUND 12Z/24 AND GROW WITH TIME. THE NAM/ECMWF SHOW THE
BEST AGREEMENT TO THE ENSEMBLE MEANS AND LIE IN THE MIDDLE OF THE
MODEL SPREAD REGARDING THE 500 MB LOW CENTER AND THE CORRESPONDING
SURFACE LOW TRACKING ACROSS THE CNTRL/NRN PLAINS. THE 12Z ECMWF
SHOWS VERY LITTLE CHANGE HERE FROM ITS 00Z RUN...AND IS MATCHED BY
THE 12Z UKMET.


BROADER UPPER LEVEL TROUGH CROSSING THE GREAT LAKES AND INTO THE
  NORTHEAST BY FRI MORNING
COLD FRONT CROSSING THE OHIO VALLEY AND MID-ATLANTIC REGION
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

ALL THE MODELS SHOW GOOD AGREEMENT HERE SO WILL PREFER A GENERAL
MODEL COMPROMISE TO IRON OUT SMALLER SCALE DIFFERENCES.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...


OTTO

$$




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