Prognostic Meteorological Discussion
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000
FXUS10 KWNH 040438
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1138 PM EST TUE MAR 03 2015

VALID MAR 04/0000 UTC THRU MAR 07/1200 UTC

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

00Z NAM/GFS EVALUATION...INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


NORTHERN STREAM TROUGH DIGGING THROUGH THE MIDWEST/NORTHEAST
COLD FRONT SETTLING THROUGH THE EAST
SURFACE WAVE DEVELOPING ALONG THE FRONT AND IMPACTING THE
MID-ATLANTIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM AND 12Z ECMWF
CONFIDENCE: AVERAGE

DIFFERENCES WITH THIS SYSTEM ARE BECOMING RELATIVELY MINOR
COMPARED TO PREVIOUS DAYS...BUT IT APPEARS THAT THE 00Z GFS IS
STILL ON THE FAST SIDE OF THE GUIDANCE WITH A COLD FRONT SINKING
SEWD ACROSS THE MID-ATLANTIC AND SOUTHEAST CONUS. THE DIFFERENCES
ARE MORE NOTED ACROSS THE SOUTHEAST AND ARE RELATED TO THE SRN
PORTION OF THE NRN STREAM TROUGH APPROACHING THE MID-MISS VALLEY
THU MORNING. ONLY THE GEFS SUPPORTS THE GFS AT THIS TIME...WHILE
STRONGER ENSEMBLE SUPPORT FROM THE ECMWF/SREF/CMC EXISTS FOR A
SLIGHTLY SLOWER SOLUTION...BUT FASTER THAN THE 12Z UKMET...WITH
THE UKMET STILL APPEARING TOO SLOW. THIS PREFERRED TIMING IS BEST
REPRESENTED BY A BLEND OF THE 00Z NAM AND 12Z ECMWF. THE NAM HAD
BEEN SLOW WITH PREVIOUS RUNS BUT HAS TRENDED QUICKER AND IS NOW A
BIT AHEAD OF THE 12Z ECMWF.


WEAKENING CLOSED LOW NEAR THE NRN BAJA PENINSULA MOVING INTO THE
  SRN HIGH PLAINS WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS HAVE CONVERGED ENOUGH SINCE YESTERDAY AND NOW ALL SHOW
A SIMILAR EVOLUTION WITH THIS SYSTEM. THEREFORE A GENERAL MODEL
COMPROMISE IS PREFERRED.


CLOSED LOW/UPPER TROUGH REDEVELOPING OVER NWRN MEXICO THU/FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z UKMET BLEND
CONFIDENCE: A LITTLE ABOVE AVERAGE

THE MODELS SHOW ENERGY DIGGING BACK INTO PARTS OF THE FAR
SOUTHWEST U.S. AND THE BAJA PENINSULA BY THU AND FRI. OUTSIDE OF
THE 12Z UKMET...WHICH IS FARTHER TO THE WEST WITH A CLOSED LOW BY
MID-DAY FRIDAY...THE DETERMINISTIC/ENSEMBLE GUIDANCE SHOWS GOOD
AGREEMENT. THEREFORE...A NON 12Z UKMET BLEND IS PREFERRED.


SHORTWAVE MOVING DOWN THROUGH SWRN CANADA ON FRI...REACHING THE
  N-CNTRL U.S. SAT MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS...12Z ECMWF...12Z CMC BLEND
CONFIDENCE: A LITTLE BELOW AVERAGE

THE MODELS ARE FORECASTING SHORTWAVE ENERGY FROM THE GULF OF
ALASKA TO TRACK INTO WESTERN CANADA ON THU...ATOP A STRONG
MID-LEVEL RIDGE CENTERED NEAR NRN CALIFORNIA. THE 00Z NAM BECOMES
THE WEAKEST SOLUTION IN TIME WITH THIS ENERGY...AND THE 12Z UKMET
IS TOWARD THE STRONGER SIDE OF THE GUIDANCE WITH TWO DEFINED
SHORTWAVES MAKING THEIR WAY INTO THE N-CNTRL CONUS. THE 00Z GFS IS
ALSO ON THE STRONGER SIDE...BUT NOT LIKE THE UKMET...AND HAS
AGREEMENT IN TIMING WITH THE ENSEMBLE MEANS AND 12Z ECMWF/CMC.
POOR RUN TO RUN CONTINUITY IN THE MODELS REDUCES CONFIDENCE
SOMEWHAT.


...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

$$





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