Prognostic Meteorological Discussion
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000
FXUS10 KWNH 020444
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1143 PM EST SUN MAR 01 2015

VALID MAR 02/0000 UTC THRU MAR 05/1200 UTC

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

00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


INITIAL UPPER LOW/TROUGH OVER CALIFORNIA REACHING THE CNTRL ROCKIES
  MON NIGHT
ASSOCIATED SFC LOW / COLD FRONT MOVING OUT INTO THE CNTRL PLAINS
  TUE MORNING AND THROUGH THE DAY ON TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS...12Z ECMWF BLEND
CONFIDENCE: AVERAGE

TIMING DIFFERENCES BEGIN TO APPEAR WITH THE REMNANT SHORTWAVE AS
IT REACHES THE CNTRL PLAINS EARLY TUE ALONG WITH THE ASSOCIATED
COLD FRONT EXTENDING WWD ACROSS THE ROCKIES. THE 00Z NAM AND 12Z
CMC ARE SLIGHTLY SLOWER WITH THE SHORTWAVE COMPARED TO THE
AGREEABLE 00Z GFS AND 12Z ECMWF. CURRENTLY...THE GFS/ECMWF AGREE
WELL WITH THE LATEST ENSEMBLE MEANS DESPITE NOTABLE REMAINING
ENSEMBLE SPREAD...WITH THE 12Z UKMET GETTING A BIT AHEAD BY LATER
TUESDAY WITH THE COLD FRONT. BEYOND TUE...AN UPPER TROUGH MOVING
ACROSS THE NRN PLAINS TAKES OVER AND IMPACTS A COLD FRONT REACHING
THE SOUTHEAST...DISCUSSED IN THE NEXT SECTION.


UPPER TROUGH AXIS DROPPING OUT OF CANADA INTO THE N-CNTRL U.S. TUE
EVENTUAL STRONG COLD FRONT REACHING THE SOUTHEAST THU MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF
CONFIDENCE: A LITTLE BELOW AVERAGE

THE 00Z NAM AND 12Z UKMET ARE TOWARD THE SLOWER SIDE WITH THE
EVENTUAL LONG WAVE TROUGH THAT FORMS OVER THE CNTRL PLAINS WED AND
THE ASSOCIATED COLD FRONT WORKING EWD...AND THE 00Z GFS IS ON THE
FAST SIDE RELATIVE THE REMAINING MODEL GUIDANCE. THE SREF/GEFS/EC
MEANS SUGGEST THE GFS IS TOO WEAK WITH A SOUTHEAST UPPER RIDGE
WHICH ALLOWS THE COLD FRONT TO MORE QUICKLY PROGRESS SOUTH AND
EAST. THE ECMWF HAS BEEN TRENDING SLOWER SINCE YESTERDAY BUT
CURRENT ENSEMBLE MEANS SUPPORT A FASTER SOLUTION THAN THE SLOWER
NAM/UKMET AT THIS TIME. ENSEMBLE SPREAD REMAINS LARGE WHICH LOWERS
CONFIDENCE AND PREFER TO STAY TOWARD THE MIDDLE AT THIS TIME.


SECONDARY SHORTWAVE ENERGY DIVING SOUTH OFF CALIFORNIA TODAY
CROSSING BACK INTO SOUTHWEST STATES LATE TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS / 12Z ECMWF BLEND
CONFIDENCE: AVERAGE

THE MODELS SHOW REASONABLY CLOSE AGREEMENT HERE AFTER TRENDING
TOWARD A COMMON MIDDLE GROUND...BUT WITH THE REMAINING
SPREAD...PREFER TO STAY TOWARD THE MIDDLE WHICH IS BEST
REPRESENTED BY THE 00Z GFS AND 12Z ECMWF.


...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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