Prognostic Meteorological Discussion
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FXUS10 KWNH 291624
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1223 PM EDT FRI APR 29 2016

VALID APR 29/1200 UTC THRU MAY 03/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS

...WEAKENING UPPER LOW OVER LOWER MI...
...EXITING SURFACE LOW FROM THE MID-ATLANTIC REGION...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: AVERAGE

THERE IS MINIMAL MASS FIELD SPREAD WITH THE WEAKENING UPPER LOW
AND ITS SHEARING ENERGY ACROSS THE MID-ATLANTIC REGION THROUGH
SAT. WEAK LOW PRESSURE NEAR THE MID-ATLANTIC COAST IS AGREED UPON
BY THE GUIDANCE TO QUICKLY EXIT OUT TO SEA TONIGHT AND SAT.


...UPPER LOW EJECTING OUT OF THE FOUR CORNERS...
...ENERGY EJECTING OUT ACROSS THE MIDWEST
...LOW PRESSURE MOVING FROM THE PLAINS TO THE MID-ATLANTIC...

PREFERENCE: BLEND OF THE 12Z GFS/00Z UKMET AND 00Z ECMWF
CONFIDENCE: AVERAGE

THE STRONGEST MODEL CLUSTERING WITH THIS SYSTEM RESIDES WITH THE
12Z GFS/00Z UKMET AND 00Z ECMWF...AS THE 00Z CMC GRADUALLY BECOMES
A BIT TOO SLOW AND DEEP...AND THE 12Z NAM TOO WEAK AND
PROGRESSIVE. STRONGER ENSEMBLE SUPPORT FAVORS THE GFS/UKMET/ECMWF
CAMP FOR TIMING AND DEPTH...AND THIS CONSENSUS WILL BE PREFERRED.


...CLOSED UPPER LOW EVOLVING OVER THE WEST THIS WEEKEND...

PREFERENCE: GENERAL MODEL COMPROMISE...THROUGH 60 HOURS
            BLEND OF THE 06Z GEFS MEAN/00Z ECENS MEAN...AFTER 60
HOURS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS ALL STRONGLY AGREE IN DIGGING AN UPPER TROUGH ACROSS
THE NORTHWEST AND DOWN THROUGH THE GREAT BASIN THROUGH SAT. ON SUN
AND MON...THE UPPER LOW WILL BROADEN AND EXPAND OVER THE SOUTHWEST
AND INTO THE CENTRAL ROCKIES. VERY GOOD AGREEMENT EXISTS THROUGH
SUN...AND A GENERAL MODEL COMPROMISE CAN BE PREFERRED THROUGH THIS
PERIOD. HOWEVER...SPREAD INCREASES IN THE HEIGHT FALL EVOLUTION
THEREAFTER...AND AT THIS POINT A BLEND OF THE GEFS MEAN AND ECENS
MEAN SHOULD SUFFICE.


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

PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF...THROUGH 60 HOURS
            BLEND OF THE 06Z GEFS MEAN/00Z ECENS MEAN...AFTER 60
HOURS
CONFIDENCE: AVERAGE

THE MODELS TAKE A NORTHERN STREAM TROUGH SOUTHEAST FROM ONTARIO
AND INTO THE GREAT LAKES REGION BY SAT. BY SUN...THE UKMET BECOMES
STRONGER AND A BIT SLOWER WITH THE MID LEVEL SYSTEM NORTH OF LAKE
HURON AND A BIT SHARPER WITH A MID LEVEL TROF LAGGING OVER THE
DAKOTAS. STRONGER MODEL CLUSTERING FAVORS THE 12Z GFS AND 00Z
ECMWF THROUGH SUN...AND THEREAFTER A BLEND OF THE 06Z GEFS MEAN
AND 00Z ECENS MEAN WILL BE PREFERRED.


...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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