Prognostic Meteorological Discussion
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000
FXUS10 KWNH 210629
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 AM EDT THU AUG 21 2014

VALID AUG 21/0000 UTC THRU AUG 24/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF


...UPPER TROUGHING MOVING FROM THE GREAT LAKES ACROSS THE
NORTHEAST...
...COLD FRONT SINKING SWD THROUGH THE EAST COAST STATES...

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM ENDS UP ON THE DEEPER END OF THE GUIDANCE CONCERNING
THE 500 MB TROUGH EVOLVING IN THE WRN ATLANTIC BY THIS WEEKEND
WHICH CAUSES THE NAM TO BE ON THE SOUTH SIDE WITH A COLD FRONT
THAT SETTLES SOUTH INTO THE SERN STATES. THE 00Z GFS AND 00Z ECMWF
WILL CONTINUE TO BE FAVORED IN KEEPING WITH CONTINUITY AND THESE
MODELS ARE WELL CLUSTERED.


...WEAKENING MID-LEVEL DISTURBANCE LIFTING NEWD FROM THE
SOUTHWEST...

PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS SOMEWHAT OF A STRONGER OUTLIER WITH THE ENERGY THAT
EJECTS NEWD OUT OF THE SOUTHWEST THE NEXT COUPLE OF DAYS AND AHEAD
OF THE LARGER SCALE TROUGH/CLOSED LOW THAT DIGS SWD INTO THE
WESTERN U.S. BY THIS WEEKEND. WILL FAVOR A NON-NAM COMPROMISE AS A
RESULT...ESP AS THE REMAINING GLOBAL MODELS ARE REASONABLY WELL
CLUSTERED WITH THEIR MASS FIELDS.


...UPPER TROUGHING/CLOSED LOW DIGGING INTO THE WESTERN U.S...
...LOW PRESSURE DEVELOPING OVER THE CENTRAL/NORTHERN PLAINS...

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF...THROUGH 72 HRS
            00Z ECMWF...72 HRS TO 84 HRS
CONFIDENCE: AVERAGE

THE MODELS ARE IN GOOD AGREEMENT ON AMPLIFYING AN UPR TROUGH OVER
THE WESTERN U.S. THE NEXT COUPLE OF DAYS WITH THE ENERGY THEN
ENCROACHING ON THE NRN HIGH PLAINS BY SUN. A COMBINATION OF THIS
AND LEAD SHORTWAVE ENERGY EJECTING NEWD OUT OF THE SOUTHWEST WILL
ALSO HELP TO DRIVE SFC LOW PRESSURE OVER THE CNTRL AND NRN PLAINS.
THE 00Z GEM HAS TRENDED A LITTLE SLOWER WITH ITS HEIGHT FALL
EVOLUTION...BUT IS STILL A LITTLE MORE PROGRESSIVE WITH ITS SFC
LOW EVOLUTION OVER THE PLAINS AND TWD THE UPR MIDWEST THROUGH THE
PERIOD. THE GEM IS ALSO A TAD WEAKER THAN THE MODEL CONSENSUS
ALOFT. THE 00Z UKMET HAS ALSO TRENDED A LITTLE SLOWER AND IS
RATHER CLOSE TO THE GLOBAL MODEL CONSENSUS ALOFT. THE 00Z NAM IS
THE MOST AMPLIFIED SOLN ALOFT AND ESP AT THE SFC WITH ITS LOW
CENTER LIFTING NWD THROUGH THE NRN PLAINS. THE 00Z GFS IS WELL
CLUSTERED WITH THE 00Z ECMWF UNTIL ABOUT 72 HRS WHEN IT BECOMES
MORE AMPLIFIED WITH THE UPR TROUGH BY SUGGESTING A NEG TILT...AND
ALSO TUCKING A STRONGER SFC LOW FARTHER BACK TO THE WEST OVER WRN
ND. THE 00Z ECMWF HAS STRONGER ENSEMBLE SUPPORT WITH THE GEFS MEAN
AND ECENS MEAN. WILL FAVOR A BLEND OF THE 00Z GFS AND 00Z ECMWF
THROUGH 72 HRS...AND THEN THE 00Z ECMWF THEREAFTER.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

$$




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