Prognostic Meteorological Discussion
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FXUS10 KWNH 051846
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT TUE MAY 05 2015

VALID MAY 05/1200 UTC THRU MAY 09/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE UKMET/CMC/ECMWF ALONG WITH
FINAL PREFERENCES

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SHORTWAVE OVER THE PACIFIC NORTHWEST DROPPING INTO THE SOUTHWEST
WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/12Z ECMWF
CONFIDENCE: ABOVE AVERAGE

THE 12Z NAM CONTINUED ITS TREND OF A SLOWER AND DEEPER SOLUTION AS
THE SHORT WAVE DROPS INTO THE SOUTHWEST STATES AND CLOSES
OFF...ESPECIALLY DURING DAY 2. THE 12Z GFS REMAINED FAIRLY STEADY
WITH ITS PROGRESSION...AND HAD THE 12Z GEFS MEAN SUPPORT. THE 12Z
GFS/12Z ECMWF COMBINATION STILL SHOWS THE BEST CONTINUITY WITH
THIS FEATURE...AND THE 12Z CMC GLOBAL AND UKMET WERE CLOSE TO THE
CONSENSUS AS WELL.


SHORTWAVE TRACKING FROM THE SOUTHWEST TOWARDS THE CENTRAL PLAINS
WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~
PREFERENCE: 12Z GFS/12Z ECMWF
CONFIDENCE: AVERAGE

THE 12Z NAM IS SLOWER EJECTING THE SHORT WAVE FROM THE SOUTHWEST
ACROSS THE CENTRAL PLAINS... ESPECIALLY DURING THE DAY 2/3 TIME
FRAME. THE 12Z GFS REMAINED STEADY WITH THIS FEATURE...AND HAD THE
SUPPORT OF THE 12Z GEFS MEAN. THE 12Z GFS/12Z ECMWF COMBINATION
SHOWS THE BEST CONTINUITY WITH THIS FEATURE...WITH THE 12Z CMC
GLOBAL AND UKMET FASTER WITH THE SHORT WAVE... ESPECIALLY DURING
DAY 3.


LOW PRESSURE NEAR THE SOUTHEAST COAST BY FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/12Z CMC
CONFIDENCE: BELOW AVERAGE

THE 12Z NAM CONTINUES ITS TREND OF BRINGING THE SURFACE LOW
NORTHWEST INTO THE SC COAST DURING THE FIRST PART OF DAY 3...AND
THE 12Z GFS COMES ASHORE WITH THE SURFACE LOW ABOUT 6 HOURS LATER
NEAR THE SC/NC COAST (THE 12Z GFS ALSO CONTINUED ITS TREND OF
COMING ASHORE MORE QUICKLY). THE 12Z GEFS MEAN NOT SURPRISINGLY
WAS FURTHER WEST WITH ITS SOLUTION...THOUGH NOT AS FAR WEST AS THE
OPERATIONAL 12Z GFS.

THE 12Z UKMET WAS A BIT FURTHER WEST WITH ITS SOLUTION...BUT THE
12Z ECMWF/CMC GLOBAL WERE ALSO FURTHER WEST WITH THEIR LOW
PLACEMENTS BY DAY 3. IT WOULD APPEAR AS THOUGH THE MODEL TREND OF
MOVING THE SURFACE LOW TO THE WEST IN THE NON-NCEP GUIDANCE WAS A
MOVE IN THE RIGHT DIRECTION. THIS WAS BORNE OUT EARLIER IN THE
ECMWF/CMC ENSEMBLE SCATTER LOW PLOTS.

FOR NOW...A BLEND OF THE 12Z ECMWF/CMC GLOBAL LOOKS LIKE A GOOD
CONSENSUS POSITION FOR THE SURFACE LOW. HOWEVER...UNTIL A CLEAR
TREND IN THE NCEP VS NON-NCEP CAMPS CAN BE ESTABLISHED CONCERNING
THE PLACEMENT OF THE SURFACE LOW...PARTICULARLY ON DAY
3...FORECAST CONFIDENCE REMAINS BELOW AVERAGE.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

HAYES

$$




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