Prognostic Meteorological Discussion
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FXUS10 KWNH 301851
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM EDT MON MAR 30 2015

VALID MAR 30/1200 UTC THRU APR 03/0000 UTC

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

12Z MODEL PREFERENCES...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.

...SHORTWAVE CROSSING NEW ENGLAND THROUGH EARLY TUES...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THERE IS GOOD MODEL AGREEMENT WITH THE DETAILS OF THE SHORTWAVE
TROUGH EXITING THROUGH NEW ENGLAND TONIGHT AND EARLY TUES. A
GENERAL MODEL COMPROMISE WILL BE PREFERRED AT THIS POINT.


...SHORTWAVE CROSSING THE UPPER MS VALLEY/GREAT LAKES THROUGH
TUES...
...SURFACE LOW CROSSING THE MID ATLANTIC STATES...

PREFERENCE: BLEND OF THE 12Z GFS/12Z ECMWF...THROUGH 36 HOURS
            BLEND OF THE 12Z ECMWF/12Z UKMET...AFTER 36 HOURS
CONFIDENCE: AVERAGE

THE 12Z GEM IS A BIT DEEPER AND SLOWER THAN THE CONSENSUS WITH ITS
SHORTWAVE AND ASSOCIATED SURFACE LOW THAT DROPS SOUTHEAST FROM THE
MIDWEST AND ACROSS THE MID-ATLANTIC REGION THROUGH TUES. ONCE THE
LOW MOVES OFFSHORE THE MID-ATLANTIC...THE GEM REMAINS A
SLOWER/DEEPER OUTLIER...WITH THE 12Z GFS BECOMING A FASTER AND
WEAKER OUTLIER. THE STRONGER MODEL CLUSTERING OFFSHORE RESIDES
WITH THE 12Z ECMWF AND 12Z UKMET. SO...AN INITIAL PREFERENCE
TOWARD THE GFS AND ECMWF WILL TRANSITION TO ECMWF AND UKMET AFTER
ABOUT 36 HOURS.


...MID LEVEL TROUGH CROSSING THE SOUTHERN PLAINS/TN VALLEY TUES
THROUGH THURS...

PREFERENCE: BLEND OF THE 12Z GFS/12Z ECMWF AND 12Z GEM
CONFIDENCE: AVERAGE

THE 12Z NAM IS CLOSE TO THE CONSENSUS THROUGH TUES BUT TENDS TO
BECOME A BIT DEEPER/SHARPER WITH THE ENERGY CROSSING THE SOUTHERN
PLAINS THEREAFTER. BY THURS...THE 12Z NAM IS SLOWER AND STRONGER
WITH THE ENERGY AS IT LIFTS INTO THE TN VALLEY REGION...WITH THE
12Z UKMET GENERALLY FASTER AND WEAKER. THIS LEAVES THE 12Z GFS/12Z
ECMWF AND 12Z GEM WHICH ARE RELATIVELY WELL CLUSTERED...ALTHOUGH
THE 12Z ECMWF MAY TEND TO BE A LITTLE ON THE STRONG SIDE WITH ITS
ENERGY TRAVERSING SOUTHERN TX AND ACROSS THE GULF COAST STATES.
THE LATEST GEFS MEAN AND ECENS MEAN SUPPORT THE DETERMINISTIC GFS
AND ECMWF RESPECTIVELY...AND SO WILL PREFER TO MAINTAIN CONTINUITY
AND COMPROMISE BY BLENDING THE 12Z GFS/12Z ECMWF AND 12Z GEM.


...LONGWAVE TROUGH ENTERING THE NORTHWEST...
...ENERGY EJECTING OUT ACROSS THE NORTHERN PLAINS/UPPER MIDWEST...

PREFERENCE: 12Z ECMWF
CONFIDENCE: BELOW AVERAGE

THE 12Z NAM REMAINS OVERALL A BIT DEEPER THAN THE MULTI-MODEL
CONSENSUS WITH THE LONGWAVE TROUGH APPROACHING THE NORTHERN PLAINS
AND UPPER MIDWEST OVER THE NEXT FEW DAYS. THE 12Z GEM IS OVERALL
THE SLOWEST SOLUTION...WITH THE 12Z ECMWF AND 12Z UKMET A LITTLE
MORE PROGRESSIVE. THESE SOLUTIONS ARE ALL SLOWER THAN THE 12Z GFS
WHICH IS GENERALLY A FAST OUTLIER AFTER ABOUT 60 HRS. EVEN THE 12Z
GEFS MEAN IS A TAD SLOWER THAN THE DETERMINISTIC GFS. ACCOUNTING
FOR THE OVERALL SPREAD WITH TIMING AND DEPTH...WILL PREFER TO LEAN
TOWARD THE 12Z ECMWF. CONFIDENCE REMAINS LIMITED THOUGH GIVEN THE
OVERALL SPREAD.


...SHORTWAVE CROSSING THE PACIFIC NORTHWEST INTO THE GREAT BASIN
WED...

PREFERENCE: BLEND OF THE 12Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

SOME MODEST DIFFERENCES CONTINUE AMONG THE MODELS WITH THE
SHORTWAVE TROUGH DIGGING ACROSS THE GREAT BASIN BY WED AND THURS.
THE 12Z GEM AND 12Z NAM TEND TO BE RELATIVELY SLOWER AND DEEPER
WITH THE HEIGHT FALLS...WITH THE 12Z UKMET FASTER. THE 12Z ECMWF
TENDS TO BE A LITTLE MORE PROGRESSIVE LIKE THE UKMET...WITH THE
12Z GFS A BIT SLOWER LIKE THE NAM AND GEM. A COMPROMISE BETWEEN
CAMPS IS PREFERRED WHICH IS SUPPORTED BY THE LATEST GEFS MEAN AND
ECENS MEAN. THIS WOULD SUGGEST BLENDING THE 12Z 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...

ORRISON

$$




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