Prognostic Meteorological Discussion
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FXUS10 KWNH 250700
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT THU AUG 25 2016

VALID AUG 25/0000 UTC THRU AUG 28/1200 UTC

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

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


...WEAK TROUGH CROSSING THE LOWER GREAT LAKES/NEW ENGLAND ON
THURS...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS JUST A TAD STRONGER THAN THE GLOBAL MODEL CONSENSUS
WITH THIS SYSTEM...AND AS A RESULT...WILL PREFER A NON-NAM
CONSENSUS GIVEN THE EXCELLENT GLOBAL MODEL CLUSTERING.


...MID LEVEL TROUGH CLIPPING THE NORTHERN PLAINS/UPPER MS VALLEY...
...ENERGY LIFTING ACROSS ONTARIO/QUEBEC THROUGH FRI...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE MODELS ARE IN GOOD AGREEMENT NOW WITH THIS SYSTEM...BUT THE
00Z NAM SUGGESTS A SOMEWHAT STRONGER MID LEVEL TROUGH VERSUS THE
REMAINING WELL CLUSTERED GUIDANCE. A NON-NAM CONSENSUS WILL BE
PREFERRED.


...MID LEVEL TROUGH EJECTING OUT INTO THE CENTRAL PLAINS THURS...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW GOOD AGREEMENT IN WEAKENING THIS SYSTEM OVER THE
NEXT DAY OR SO AS IT EJECTS OUT OF THE SOUTHERN ROCKIES AND INTO
THE CENTRAL PLAINS. A GENERAL MODEL COMPROMISE WILL BE PREFERRED.


...UPPER TROUGH CROSSING THE NORTHERN ROCKIES THURS...
...ENERGY REACHING THE NORTHERN PLAINS/MIDWEST SAT/SUN...

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

THE DIFFERENCES WITH THIS SYSTEM ARE FAIRLY MINOR THROUGH 60
HOURS...ALTHOUGH THEREAFTER THE 00Z NAM GRADUALLY BECOMES A BIT OF
A DEEPER OUTLIER SOLUTION. THE 00Z UKMET BECOMES MORE PROGRESSIVE
THAN THE MODEL CONSENSUS...WITH THE 00Z GFS/00Z CMC AND 00Z ECMWF
ALL CLUSTERED A BIT SLOWER...WITH THE 00Z ECMWF OVERALL THE
SLOWEST SOLUTION. THE GFS AND ECMWF CONTINUE TO BE SUPPORTED BY
THEIR RESPECTIVE ENSEMBLE MEANS...AND SO A BLEND OF THE GFS AND
ECMWF WILL BE PREFERRED.


...UPPER TROUGH DROPPING SOUTH THROUGH BRITISH COLUMBIA...

PREFERENCE: BLEND OF THE 00Z UKMET AND 00Z ECMWF
CONFIDENCE: BELOW AVERAGE

ALL OF THE MODELS SHOW A SHORTWAVE TROUGH CROSSING SOUTHERN AK ON
THURS WHILE TRAVERSING THE NORTH SIDE OF A VERY STRONG MID/UPPER
LEVEL RIDGE OVER THE GULF OF AK. THIS ENERGY WILL THEN DIG SHARPLY
SOUTH DOWN THE EAST SIDE OF THE RIDGE AND AMPLIFY WHILE CROSSING
BRITISH COLUMBIA. THE 00Z UKMET/00Z CMC AND 00Z ECMWF HAVE COME
INTO AGREEMENT ON A SOLUTION THAT IS MORE PROGRESSIVE THAN THE 00Z
NAM AND 00Z GFS. THE CMC THOUGH GRADUALLY APPEARS TO BE TOO DEEP.
THE GFS THOUGH APPEARS GENERALLY TO BE TOO FLAT/WEAK. CONFIDENCE
IS LIMITED...BUT WILL LEAN TOWARD THE STRONGER CLUSTERING OF THE
UKMET AND ECMWF AS A COMPROMISE AT THIS POINT BETWEEN THE FLATTER
GFS AND STRONGER/SHARPER CMC.


...WEAK MID LEVEL TROUGH OVER THE SOUTHWEST THIS WEEKEND...

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

THE MODELS PINCH OFF SOME SOUTHERN STREAM SHORTWAVE ENERGY OVER
THE SOUTHWEST THIS PERIOD...AND THERE IS GENERALLY MINOR SPREAD IN
THE GUIDANCE. SOMEWHAT BETTER MODEL CLUSTERING DOES RESIDE WITH
THE 00Z GFS AND 00Z ECMWF...SO A BLEND OF THESE SOLUTIONS WILL BE
PREFERRED.


...LOW PRESSURE APPROACHING SOUTH FLORIDA BY SUN...

PREFERENCE: BLEND OF THE 00Z UKMET/00Z CMC AND 00Z ECMWF
CONFIDENCE: BELOW AVERAGE

A BROAD AREA OF LOW PRESSURE LOCATED NORTH OF PUERTO RICO IS
FORECAST TO MOVE WEST-NORTHWEST THROUGH THE CENTRAL AND SOUTHEAST
BAHAMAS AND AT LEAST APPROACH SOUTHEAST FL OR THE FL KEYS BY LATE
IN THE WEEKEND. THE 00Z NAM IS A STRONG OUTLIER SOLUTION THAT IS
SLOWER AND WELL TO THE RIGHT OF THE MODEL CONSENSUS. THE 00Z
UKMET/00Z CMC AND 00Z ECMWF ARE ACTUALLY ALL CLUSTERING TOGETHER
RATHER NICELY NOW AT THIS POINT...WITH A SOLUTION FARTHER LEFT AND
FASTER THAN THE NAM...BUT NOT AS DEEP. THE NON-NCEP SOLUTIONS
COLLECTIVELY SUGGEST A MORE DIRECT IMPACT TO SOUTH FL BY LATE SUN.
THE 00Z GFS IS STICKING OUT AS A RELATIVELY WEAK OUTLIER BY
COMPARISON WITH A LOW TRACK THAT IS FARTHER SOUTH WITH MORE OF A
POTENTIAL IMPACT ON THE FL KEYS AT THE END OF THE PERIOD. WILL
FAVOR A CONSENSUS OF THE NON-NCEP SOLUTIONS AT THIS TIME.

ORRISON

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

$$





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