Prognostic Meteorological Discussion
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FXUS10 KWNH 190506
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
105 AM EDT SUN APR 19 2015

VALID APR 19/0000 UTC THRU APR 22/1200 UTC

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

==============================================
00Z MODEL EVALUATION AND PREFERENCES
==============================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==============================================

...CENTRAL AND EASTERN U.S...

PREFERENCE: BLEND OF 18/12Z ECMWF...18/18Z GFS...
CONFIDENCE: AVERAGE

MERGING OF THE CLOSED LOW IN THE ROCKIES WITH A DIGGING NORTHERN
STREAM SHORTWAVE WILL PRODUCE A CONSOLIDATED BROAD SCALE TROUGH
CENTERED OVER THE GREAT LAKES BY TUESDAY. MODEL AGREEMENT FROM THE
19/00Z RUN WAS NOT PARTICULARLY STRONG WITH HOW SHORTWAVE ENERGY
ALONG THE ATLANTIC COAST AND ACROSS THE WESTERN PLAINS OF CANADA.
THE 19/00Z RUN OF THE GFS SEEMED TO LATCH ON TO BOTH OF THE VORTS
AND ENDED UP WITH A SOLN NOT SUPPORTED BY THE ENS MEAN OR OTHER
GLOBAL RUNS.  THINK THE 18/18Z GFS WAS BETTER.  THE 19/00Z NAM WAS
NOT AS DEEP AS THE OTHER MODELS AND NOT AS FAST AS THE GFS IN
ROTATING THE ENERGY ACROSS THE NORTHEASTERN STATES DAY 2 AND DAY
3.


...ENERGY DROPPING SOUTHWARD OFFSHORE CALIFORNIA...

PREFERENCE: BLEND OF 19/00Z NAM/GFS AND 18/12Z ECMWF
CONFIDENCE: AVERAGE

A BROAD AND RELATIVELY WEAK UPPER LEVEL TROUGH WILL TAKE SHAPE AS
ENERGY THAT WAS NEARLY CUTOFF FROM THE MAIN BELT OF WESTERLIES
SINKS OFFSHORE OF CALIFORNIA. MODEL FORECASTS ARE VERY SIMILAR TO
ONE ANOTHER. WHILE THE DIFFERENCE BETWEEN THE CANADIAN AND
NAM/GFS/EC IDEA IS NOT EGREGIOUS...THE CANADIAN THE CANADIAN
REMAINED THE CLOSEST THING TO AN OUTLIER AS IT ALLOWS MORE
TROUGHING DOWNSTREAM INTO THE SOUTHWEST U.S. BY LATE DAY 2.  WE
PREFER THE MORE AGREEABLE CLUSTER OF THE NAM/GFS/ECMWF.


...FRONT APPROACHING THE PACIFIC NORTHWEST TUESDAY...

PREFERENCE: BLEND OF THE OPERATIONAL MODELS EXCLUDING THE GFS.
CONFIDENCE: AVERAGE

THE 19/00Z GFS WAS A SHARP/FAST OUTLIER WITH RESPECT TO THE OTHER
MODELS IN DEALING WITH THIS MID LEVEL WAVE AND ITS REFLECTION AT
THE SURFACE.  THIS WAS AN IDEA IT STARTED DURING THE 18/12Z MODEL
RUNS AND AN IDEA WHICH GARNERED MINIMAL SUPPORT FROM THE ENSEMBLES
AND FROM THE ECMWF/NAM THINKING.

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

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

BANN

$$





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