Prognostic Meteorological Discussion
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000
FXUS10 KWNH 260659
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT SUN MAR 26 2017

VALID MAR 26/0000 UTC THRU MAR 29/1200 UTC

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

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

...CLOSED LOW CROSSING THE MID MS/OH VALLEYS SUN...
...SYSTEM WEAKENING INTO THE GREAT LAKES/NORTHEAST THROUGH MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM THROUGH MON AS
IT LIFTS TOWARD THE GREAT LAKES AND NORTHEAST AND GRADUALLY
DAMPENS OUT. A GENERAL MODEL COMPROMISE WILL BE PREFERRED.


...NORTHERN STREAM TROUGH EXITING THE NORTHERN ROCKIES...
...EJECTING ACROSS THE NORTHERN PLAINS/UPPER MIDWEST SUN/MON...
...REACHING THE ONTARIO/QUEBEC BORDER TUES EVENING...
...POSSIBLE SHORTWAVE PHASING OVER NEW ENGLAND BY WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

THE MODELS ADVERTISE THE NORTHERN STREAM COMPONENT OF A LARGER
SCALE WESTERN U.S. TROUGH EJECTING OUT OF THE NORTHERN ROCKIES AND
ADVANCING PROGRESSIVELY EASTWARD ACROSS SOUTHERN CANADA AND THE
FAR NORTHERN PLAINS/UPPER MIDWEST REGION THROUGH SUN AND MON. BY
LATE TUES...THE ENERGY WILL BE MOVING ACROSS ONTARIO AND QUEBEC
AND POTENTIALLY AMPLIFYING ACROSS NEW ENGLAND BY WED. THE KEY TO A
MORE AMPLIFIED SOLUTION IS THE POTENTIAL FOR SOME SHORTWAVE
PHASING AS REMNANT SOUTHERN STREAM ENERGY LIFTS NORTHEAST ACROSS
THE OH VALLEY/NORTHEAST MON AND TUES.

THE 00Z CYCLE OF THE GFS CONTINUES TO STAND OUT SIGNIFICANTLY AS A
DEEPER SOLUTION...WITH A STRONGER SURFACE LOW EJECTING OUT OF THE
OH VALLEY AND MUCH MORE DEEPENING OVER NEW ENGLAND. THE 00Z NAM
TENDS TO SUPPORT A WEAKER VERSION OF THE GFS...BUT THE 00Z ECMWF
AND ESPECIALLY THE 00Z CMC ARE FLATTER WITH THE ENERGY WITH LITTLE
IF ANY PHASING. THE 00Z UKMET AND TO SOME EXTENT THE 00Z ECMWF
HOWEVER DID TREND MORE AMPLIFIED AND ACTUALLY THE UKMET IS ONLY A
LITTLE WEAKER THAN THE GFS. THE GFS AND UKMET DO HAVE SUPPORT FROM
A LARGE NUMBER OF GEFS MEMBERS...BUT THE EARLIER EURO AND CANADIAN
MEMBERS WERE GENERALLY MUCH FLATTER THAN THE GEFS MEMBERS. SINCE
THE GFS IS OVERALL STILL A BIT OF A STRONG OUTLIER AND THE CMC A
WEAK OUTLIER...A COMPROMISE IN BETWEEN WILL BE PREFERRED...HOWEVER
AT THIS POINT THE MODEL CONSENSUS IS STRONGER THAN THE PREVIOUS
MODEL CONSENSUS. THE SLIGHTLY WEAKER 00Z UKMET AND 00Z GEFS MEAN
WILL BE PREFERRED AS A BLEND...WHICH WILL SUPPORT THE BELIEF THAT
LATER RUNS OF THE ECMWF WILL GRADUALLY TREND A BIT STRONGER WHILE
THE GFS TRENDS PERHAPS JUST A TAD WEAKER. CONFIDENCE IS VERY
LIMITED.


...SOUTHERN STREAM UPPER TROUGH CURRENTLY OVER THE FOUR CORNERS...
...ENERGY EJECTING INTO THE CNTRL/SRN PLAINS SUN NIGHT/MON...
...SYSTEM WEAKENING INTO THE OH VALLEY/NORTHEAST MON NIGHT/TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z UKMET AND 00Z GEFS MEAN
CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE BY END OF PERIOD

THE MODELS ARE IN VERY GOOD AGREEMENT WITH THIS SYSTEM THROUGH
ABOUT 36 HOURS...HOWEVER SOME IMPORTANT TIMING DIFFERENCES ARE
NOTED THEREAFTER AS THE SYSTEM EXITS THE MID MS VALLEY AND MOVES
INTO THE OH VALLEY AND EVENTUALLY THE NORTHEAST. THE 00Z GFS WHICH
HAD TENDED TO BE THE FASTEST SOLUTION WITH THIS SYSTEM ONCE IT
REACHES THE OH VALLEY IS GAINING SOME SUPPORT TO BE MORE
PROGRESSIVE FROM THE 00Z UKMET AND ALREADY HAS SUPPORT FROM A MORE
PROGRESSIVE 00Z NAM SOLUTION. THE 00Z CMC REMAINS THE SLOWEST
SOLUTION BUT HAS TRENDED FASTER...AND THE 00Z ECMWF IS A LITTLE
MORE PROGRESSIVE TOO BUT STILL LAGS THE NAM/GFS/UKMET CLUSTER. THE
00Z GFS IN ITSELF MAY ALSO STILL BE A TAD TOO STRONG WITH ITS
SURFACE WAVE AND ACTUALLY THE 00Z GEFS MEAN IS A TAD WEAKER AND
VERY CLOSE TO THE 00Z UKMET SOLUTION. WILL FAVOR A SOMEWHAT MORE
PROGRESSIVE SOLUTION BASED ON THE LATEST TRENDS AND SUGGEST A
COMPROMISE BETWEEN THE UKMET AND GEFS MEAN AT THIS POINT WHICH
REFLECTS JUST A SLIGHTLY WEAKER VERSION OF THE GFS.


...UPPER TROUGH/COLD FRONT REACHING THE WEST COAST SUN...
...WEAKER NORTHERN STREAM TROUGH OVER THE NORTHWEST MON/TUES...
...CLOSED LOW EVOLUTION INTO THE SOUTHWEST MON/TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE MODELS ARE IN GOOD AGREEMENT WITH THE INITIAL ARRIVAL OF AN
UPPER TROUGH AND COLD FRONT ACROSS THE WEST COAST ON SUN.
HOWEVER...ON MON AND TUES...THE ARE IN VERY GOOD AGREEMENT WITH
THE DEVELOPMENT OF A RATHER STRONG UPPER TROUGH AND ASSOCIATED
CLOSED LOW THAT WILL DROP DOWN THROUGH THE SOUTHWEST AND INTO THE
FOUR CORNERS REGION. THE HEIGHT FALLS WILL BE ENCROACHING ON THE
SOUTHERN HIGH PLAINS BY WED. MEANWHILE...THE MODELS SHOW A WEAKER
NORTHERN STREAM COMPONENT OF THE ORIGINAL TROUGH CROSSING THE
NORTHWEST U.S. AND EJECTING OUT INTO THE NORTHERN HIGH PLAINS BY
TUES AND WED.

THE 00Z NAM APPEARS TO BE A TAD STRONGER WITH THE SOUTHERN STREAM
HEIGHT FALLS COMPARED TO THE 00Z GLOBAL MODELS AT THIS POINT WHICH
ARE WELL CLUSTERED. FARTHER NORTH...THE 00Z NAM IS NOW JUST
SLIGHTLY WEAKER THAN THE SAME MODEL CONSENSUS.
THEREFORE...COLLECTIVELY BASED ON BETTER MODEL CLUSTERING AND
ENSEMBLE SUPPORT...A NON-NAM CONSENSUS WILL BE PREFERRED WITH THE
NORTHERN AND SOUTHERN STREAM COMPONENTS OF THIS SYSTEM.


...COLD FRONT WEAKENING INTO BRITISH COLUMBIA ON TUES...
...ONSHORE FLOW INTO THE PACIFIC NORTHWEST THROUGH TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF
CONFIDENCE: AVERAGE

THE 00Z CMC AND 00Z UKMET BOTH ARE STILL A BIT STRONGER THAN THE
00Z GFS AND 00Z ECMWF WITH THIS SYSTEM. THE 00Z NAM THOUGH IS A
BIT OF A WEAK OUTLIER. GIVEN THE WEAKER ENSEMBLE SUPPORT...WILL
FAVOR A CONSENSUS OF THE GFS AND ECMWF AT THIS POINT.


...SHORTWAVE/SURFACE LOW NEAR THE PACIFIC NORTHWEST BY WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS CONSENSUS...WEIGHTED TOWARD 00Z UKMET/00Z ECMWF
CONFIDENCE: AVERAGE

THE MODELS HAVE A SHORTWAVE AND ASSOCIATED WEAK SURFACE LOW/FRONT
ARRIVING ACROSS THE PACIFIC NORTHWEST ON WED WITH A PARTICULAR
FOCUS ON THE OLYMPIC PENINSULA. THE 00Z GFS IS A STRONGER OUTLIER
WITH THIS SYSTEM...AND SHOWS STRONGER ONSHORE FLOW IMPACTING THE
OLYMPIC PENINSULA COMPARED TO ANY OTHER MODEL. GENERALLY THE
BETTER MASS FIELD CLUSTERING RESIDES WITH THE 00Z UKMET AND 00Z
ECMWF...SO A NON-GFS CONSENSUS WILL BE PREFERRED BUT WITH MORE
WEIGHTING TOWARD THE UKMET/ECMWF SOLUTIONS.

www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

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