Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4
000
FXUS10 KWNH 250448
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1247 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 AND GFS


...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 12Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE DIFFERENCES WITH THIS SYSTEM ARE FAIRLY MINOR THROUGH 48
HOURS...ALTHOUGH THEREAFTER THE 12Z ECMWF TENDS TO SUGGEST A
SOMEWHAT SLOWER/DEEPER TROUGH MOVING INTO THE UPPER MIDWEST
COMPARED TO THE 00Z GFS WHICH IS A TAD MORE PROGRESSIVE AND A
LITTLE WEAKER. THE 00Z NAM GRADUALLY BECOMES THE DEEPEST SOLUTION
AS THE ENERGY EXITS THE UPPER MIDWEST. THE 12Z CMC GRADUALLY
BECOMES THE MOST PROGRESSIVE SOLUTION OVERALL...WITH THE 12Z UKMET
THE SLOWEST. WILL PREFER A BLEND OF THE GFS AND ECMWF GIVEN THEIR
RELATIVELY BETTER MODEL CLUSTERING AND ENSEMBLE SUPPORT.


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

PREFERENCE: NON-CMC CONSENSUS
CONFIDENCE: 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 12Z CMC IS THE MOST PROGRESSIVE WITH THE
ENERGY. THE 00Z NAM AND 00Z GFS ARE BOTH A LITTLE SLOWER THAN THE
12Z UKMET AND 12Z ECMWF. NONE OF THE MODELS ARE AS PROGRESSIVE AS
THE CMC...WITH THE NAM/GFS/UKMET AND ECMWF SHOWING A FAIR DEGREE
OF CLUSTERING...WILL SUGGEST A NON-CMC COMPROMISE.


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

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z 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 12Z ECMWF...SO A BLEND OF THESE SOLUTIONS WILL BE
PREFERRED.


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

PREFERENCE: BLEND OF THE 00Z GFS/18Z GEFS MEAN AND 12Z ECENS MEAN
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 12Z CMC
IS THE MOST PROGRESSIVE AND WEAKEST SOLUTION. THE 12Z UKMET AND
12Z ECMWF ARE IN BETWEEN THE NAM AND CMC WITH RESPECT TO TIMING
AND STRENGTH...ALTHOUGH THE UKMET IS A LITTLE NORTH OF THE ECMWF
TRACK. THE ECMWF WOULD HAVE A MORE DIRECT IMPACT ON SOUTH
FLORIDA...WITH THE UKMET IMPACTING THE NORTHWEST BAHAMAS MORE BY
THE END OF THE PERIOD. THE 00Z GFS MAINTAINS A WEAKER LOW A BIT
SOUTH OF THE ECMWF AND WOULD SUGGEST MORE IMPACT TO THE FL KEYS.
THERE IS CONSIDERABLE SPREAD AMONG THE ENSEMBLE MEMBERS WITH THE
EVOLUTION OF THIS SYSTEM...BUT THE ENSEMBLE MEANS VIA THE 12Z
ECENS MEAN AND 18Z GEFS MEAN WOULD FOR NOW FAVOR A SOLUTION CLOSER
TO THE 00Z GFS. SO A BLEND OF THESE SOLUTIONS WILL BE PREFERRED.

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...

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.