Prognostic Meteorological Discussion
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FXUS10 KWNH 281659
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1258 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 AND GFS

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

PREFERENCE: 00Z ECMWF
CONFIDENCE: 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 BIT SLOWER/DEEPER WITH THE REMNANT
ENERGY AS IT CROSSES THE REGION. THE 00Z UKMET/00Z CMC AND 00Z
ECMWF ARE ALL A LITTLE WEAKER AND A BIT FASTER. FOR THE TIME
BEING...THERE TENDS TO BE A BIT GEFS MEAN/ECENS MEAN SUPPORT
TOWARD THE NON-NCEP GUIDANCE...AT LEAST WITH THE SHORTWAVE
DETAILS. WILL MAINTAIN CONTINUITY FOR NOW AND CONTINUE LEANING
TOWARD THE ECMWF.


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

PREFERENCE: BLEND OF THE 06Z GEFS MEAN/00Z ECENS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE 00Z CMC GRADUALLY BECOMES A BIT OF AN OUTLIER WITH THE
EVOLUTION OF THIS SYSTEM IN SUGGESTING STRONGER AND SLOWER HEIGHT
FALLS OUT ACROSS THE PLAINS AND MIDWEST. THE 00Z UKMET IS LIKELY
TOO WEAK. THIS LEAVES THE 00Z ECMWF AND THE 12Z NAM AND 12Z GFS
CLUSTERED IN BETWEEN WITH DEPTH...BUT THE NAM AND ESPECIALLY THE
GFS ARE FASTER THAN THE ECMWF. THE ENSEMBLE MEANS AS PER THE 06Z
GEFS MEAN AND 00Z ECENS MEAN OFF A COMPROMISE IN BETWEEN. A BLEND
OF THESE WILL BE PREFERRED FOR THE TIME BEING.


...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 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z UKMET IS THE MOST PROGRESSIVE WITH THIS SYSTEM...WITH THE
00Z CMC SLOWER. THE 12Z NAM/12Z GFS AND 00Z ECMWF SPLIT THE
DIFFERENCE BUT CLUSTER TOGETHER RATHER WELL...AND THUS A BLEND OF
THESE SOLUTIONS WILL BE PREFERRED.


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

PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS TAKE A NORTHERN STREAM TROUGH SOUTHEAST FROM ONTARIO
AND INTO THE GREAT LAKES REGION BY SAT. THE 00Z CMC GRADUALLY
BECOMES A LITTLE SLOWER THAN THE MODEL CONSENSUS. THE REMAINING
MODELS ARE REASONABLY WELL CLUSTERED...AND SO A NON-CMC CONSENSUS
WILL BE PREFERRED AT THIS TIME.

...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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