Prognostic Meteorological Discussion
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000
FXUS10 KWNH 281838
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 PM EDT THU APR 28 2016

VALID APR 28/1200 UTC THRU MAY 02/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND ECMWF

...SHORTWAVE/SURFACE LOW PRESSURE OVER THE MIDWEST MOVING TO THE
MID-ATLANTIC BY FRI...

PREFERENCE: 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE WEAKENING UPPER LOW OVER THE MIDWEST THIS MORNING WILL SHEAR
EASTWARD ACROSS THE LOWER GREAT LAKES REGION AND NORTHERN
MID-ATLANTIC REGION THROUGH FRI. THIS WILL ALLOW SURFACE LOW
PRESSURE TO MOVE THROUGH THE OH VALLEY...WITH REDEVELOPMENT OVER
THE MID-ATLANTIC COASTAL PLAIN AND THEN THE OFFSHORE WATERS. THE
12Z GFS AND 12Z NAM ARE A TAD BIT DEEPER WITH THE REMNANT ENERGY
AS IT CROSSES THE REGION. THE 12Z UKMET/12Z CMC AND 12Z ECMWF ARE
ALL A LITTLE WEAKER AND A BIT FASTER. FOR THE TIME BEING...THERE
TENDS TO BE A BIT MORE GEFS MEAN/ECENS MEAN SUPPORT TOWARD THE
NON-NCEP GUIDANCE OVERALL...AT LEAST WITH THE SHORTWAVE DETAILS.
WILL MAINTAIN CONTINUITY FOR NOW AND CONTINUE LEANING TOWARD THE
ECMWF AT THE SURFACE AND ALOFT.


...UPPER LOW EJECTING OUT OF THE SOUTHWEST...
...LOW PRESSURE EVOLVING OVER THE PLAINS/MIDWEST FRI/SAT...

PREFERENCE: BLEND OF THE 12Z UKMET AND 12Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE 00Z CMC GRADUALLY BECOMES A BIT OF AN OUTLIER WITH THE
EVOLUTION OF THIS SYSTEM IN SUGGESTING STRONGER HEIGHT FALLS OUT
ACROSS THE PLAINS AND MIDWEST. THE 12Z GFS NOW APPEARS OVERALL TO
BE A TAD TOO PROGRESSIVE...AS THE 12Z NAM/12Z UKMET AND 12Z ECMWF
ARE ALL SLOWER BUT JUST NOT AS DEEP AS THE CMC. WILL LEAN TOWARD
THE RELATIVELY WELL CLUSTERED 12Z UKMET AND 12Z ECMWF AT THIS TIME
FOR THE DEPTH OF THE TROUGH AND THE SURFACE LOW EVOLUTION...BUT
WITH SOMEWHAT LIMITED CONFIDENCE GIVEN THE OVERALL MASS FIELD
SPREAD.


...UPPER-LEVEL TROUGH/PACIFIC COLD FRONT REACHING THE NORTHWEST
THURSDAY NIGHT...
...CLOSED UPPER-LEVEL LOW OVER THE SOUTHWEST ON SATURDAY...

PREFERENCE: BLEND OF THE 12Z NAM/12Z GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z CMC SOLUTION IS A BIT SLOWER THAN THE MODEL CONSENSUS WITH
THIS SYSTEM. LATER IN THE PERIOD...THE 12Z UKMET APPEARS TO BE A
TAD WEAKER AND A LITTLE MORE PROGRESSIVE. THE 12Z NAM/12Z GFS AND
12Z ECMWF ARE WELL CLUSTERED AND HAVE GOOD SUPPORT FROM THE GEFS
MEAN AND ECENS MEAN...SO WILL PREFER A NAM/GFS/ECMWF CONSENSUS.


...UPPER TROUGH CROSSING THE GREAT LAKES BY SAT...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS TAKE A NORTHERN STREAM TROUGH SOUTHEAST FROM ONTARIO
AND INTO THE GREAT LAKES REGION BY SAT. THERE IS SUFFICIENT MASS
FIELD AGREEMENT THAT A GENERAL MODEL COMPROMISE CAN BE PREFERRED
AT THIS POINT.

...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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