Prognostic Meteorological Discussion
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FXUS10 KWNH 051635
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1234 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 NAM/GFS ALONG WITH INITIAL
PREFERENCES

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SHORTWAVE OVER THE PACIFIC NORTHWEST DROPPING INTO THE SOUTHWEST
WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF
CONFIDENCE: 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 06Z GEFS MEAN SUPPORT. THE 12Z
GFS/00Z ECMWF COMBINATION STILL SHOWS THE BEST CONTINUITY WITH
THIS FEATURE...AND THE 00Z CMC GLOBAL AND UKMET WERE CLOSE TO THE
CONSENSUS AS WELL.


SHORTWAVE TRACKING FROM THE SOUTHWEST TOWARDS THE CENTRL PLAINS
WED/THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~
PREFERENCE: 12Z GFS/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 06Z GEFS MEAN. THE 12Z GFS/00Z ECMWF COMBINATION
SHOWS THE BEST CONTINUITY WITH THIS FEATURE...WITH THE 00Z CMC
GLOBAL AND UKMET FASTER WITH THE SHORT WAVE... ESPECIALLY DURING
DAY 3.


LOW PRESSURE NEAR THE SOUTHEAST COAST BY FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF MEAN/06Z GEFS MEAN
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). THIS IS IN STARK CONTRAST TO THE 00Z
ECMWF/CMC GLOBAL/UKMET SOLUTIONS... WHICH CONTINUE TO SHOW A
SLOWER NORTHWARD DRIFT OF THE SYSTEM...OFF THE SOUTHEAST
COAST...THROUGH THE END OF DAY 3.

THE ECMWF/GEFS/CMC ENSEMBLE SCATTER LOW PLOTS SHOWED DECENT
CLUSTERING WITH THE POSITION OF THE SURFACE LOW THROUGH DAY
1...BUT START TO DEVIATE THEREAFTER. GIVEN THE AMOUNT OF SPREAD IN
THE OPERATIONAL RUNS (MOSTLY A MORE WESTERLY NCEP CAMP VS A MOE
EASTERLY NON-NCEP CAMP)...AN ENSEMBLE MEAN APPROACH LOOKS TO
AFFORD THE STEADIEST SOLUTION.


...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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