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000
FXUS10 KWNH 250438
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1238 AM EDT WED MAY 25 2016

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

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

00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

WEAKENING UPPER LOW IN NORTHEAST WED ALONG WITH KICKER SHORTWAVE
ACROSS NORTHEAST WITH ASSOCIATED SURFACE LOW AND FRONT WED/EARLY
THURS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

A KICKER WAVE IN CENTRAL ONTARIO IS DRIFTING EAST AND WILL BEGIN
TO AMPLIFY AND HELP TO LIFT/ACCURATE THE CLOSED LOW CURRENTLY OVER
NEW ENGLAND INTO THE NORTHERN STREAM.  DURING THE KICKER`S
DIGGING...SURFACE CYCLOGENESIS TRACKS A SURFACE WAVE THROUGH SE
QUEBEC TO NEW BRUNSWICK DRAPING A FRONT PASSAGE THROUGH NEW
ENGLAND WED INTO THURS.  THE MODELS ARE A BIT SPREAD ON EXACT
POSITION OF THE SFC LOW WITH THE 00Z GFS CONTINUING A FAVORED
NORTHERN TRACK NEVER REACHING NB...WHILE THE EC/UKMET ARE A ON THE
SOUTHERN TRACK CLOSE TO N ME.  OVERALL THIS IS FAIRLY SMALL TO
SUPPORT AN OPERATIONAL MODEL BLEND AT ABOVE AVERAGE CONFIDENCE.


QUASI-STATIONARY CLOSED UPPER LOW EAST OF SOUTHERN CANADIAN ROCKIES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: AVERAGE

MODELS CONTINUE FAIRLY STRONG AGREEMENT OVERALL WITH PLACEMENT OF
THE REMNANTS OF THE CENTROID OF THE UPPER LOW ACROSS S SASK/NE MT
THOUGH INFLUENCES FROM THE SHORTWAVE MOVING OUT OF THE CENT
ROCKIES WED/THURS INDUCE SPREAD MAINLY DEPENDENT ON PROXIMITY TO
THIS FEATURE.   THE 00Z NAM IS WELL PLACED BUT IS TYPICAL OF BIAS
IS QUITE STRONG/SLOW TO SPIN DOWN BECOMING EVEN SLOWER THAN THE
12Z ECMWF/CMC ON FRI/SAT WHEN LIFTING N/NW AS IT WEAKENS.  THE 12Z
UKMET IS A BIT FARTHER NORTH INITIALLY AND MAY BE A BIT QUICK TO
LIFT NORTH AND DISSIPATE LATE FRI/SAT.  THE 00Z GFS TRENDED A BIT
WEAKER OVERALL FOR BEST ALIGNMENT IN PLACEMENT/TIMING/STRENGTH OF
THE 12Z ECMWF MATCHING THE ENSEMBLE MEANS AS WELL TO SUPPORT A 00Z
GFS/12Z ECMWF BLEND.  GIVEN PROBABILITY OF RUN TO RUN VARIABILITY
WITH RESPECT TO A WEAKENING SYSTEM INFLUENCED BY OTHER LARGER
SYSTEMS...CONFIDENCE IN THIS BLEND IS HIGH GIVEN THE CIRCUMSTANCES
BUT ONLY AVERAGE OVERALL.


SHORTWAVES MOVING OUT OF CENT. ROCKIES SOUTHWEST FLOW AMPLIFY
WED/THUR OVER
N. HIGH PLAINS AND SHIFTS INTO ONTARIO BY FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 18Z GEFS AND 12Z ECMWF/CMC BLEND
CONFIDENCE: AVERAGE

ALL MODELS ARE GENERALLY IN THE SAME PLACE IN TIMING OF THE
INITIAL WAVE AS WELL AS SECONDARY WESTERN S/W LIFTING OUT OF THE
CENTRAL ROCKIES THURS...HOWEVER PROXIMITY TO THE QUASI-STATIONARY
UL IN NE MT...HELPS INCREASE SPREAD DUE TO INFLUENCE AS WELL AS
THE RELATIVE STRENGTH OF THE SHORTWAVE FEATURES THEMSELVES.

THE 12Z UKMET REMAINS A DEEP OUTLIER WITH THE INITIAL WAVE MOST
NOTICEABLE AT 7H. 00Z NAM CONTINUES TO BE WEST OF THE CLUSTER
EJECTING THE INITIAL WAVE AND WITH A DEEP QUASI-STATIONARY UL AS
WELL...SEEMS TO DOUBLE DOWN ON A STRONGER SOLUTION WHICH HAS NOT
BEEN THE TREND.  THE 00Z GFS BROKE WITH FAIRLY GOOD CONTINUITY
WITH A FASTER EJECTION OF THE LEAD WAVE/SURFACE LOW THAT
GRAVITATES WEST FOR THE SECOND WAVE ON THURS...SHIFTING THE
OVERALL PATTERN WEST AS WELL.  THE 12Z CMC/ECMWF HAVE THEIR OWN
FAULTS BEING ON THE EASTERN SIDE OF THE BEST PACKING SEEN IN THE
GEFS/ECENS SURFACE CLUSTER...AND THOUGH SUPPORTED BY GOOD
ALIGNMENT OF THE UKMET MAY BE A BIT TOO FAR EAST.  AS A COMPROMISE
WILL SUPPORT A 18Z GEFS TO REPLACE THE GFS ALONG WITH THE 12Z
ECMWF/CMC IN A BLEND AT AVERAGE CONFIDENCE.


CLOSED LOW NEARING S CA TRANSLATES ACROSS SOUTHWEST THURS AND
EJECTS INTO CENTRAL PLAINS FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: AVERAGE

STRONG AGREEMENT EXISTS PRIOR TO THE WAVE EJECTING INTO THE PLAINS
27/12Z...AT THIS POINT THE 00Z NAM/GFS AND 12Z UKMET ARE A BIT
MORE PROGRESSIVE AND LIFT NORTHWARD FASTER WHICH MAY BE A SHADE
TOO FAST GIVEN THE 21Z SREF/18Z GEFS.  THE 12Z ECENS SHOWS A LARGE
VARIATION PARTICULARLY IN THE SURFACE CLUSTER WHILE THE CMCE/GEFS
MEMBERS WERE TIGHTER INTERNAL TO THEIR BLEND...GIVEN THE 12Z ECMWF
IS MUCH WEAKER WITH THE WAVE OVERALL AND EVEN SLOWER THAN THE
ECENS MEAN...THERE IS SOME QUESTION TO IT.  THE 12Z CMC IS MOST
OUT OF PHASE EJECTING SLOWER AND MORE BROADLY OVERALL TO BE
MISSHAPED TO THE REST OF THE GUIDANCE TO SUPPORT IT.  TO ENCOMPASS
THE MOST LIKELY SCENARIO WILL FAVOR A NON-CMC BLEND AS OVERALL
SHAPE/TIMING PLACEMENT IS MODERATE...THOUGH WOULD FAVOR WEIGHTING
TOWARD THE 00Z GFS...AS MOST CENTRAL REPRESENTATIVE.


UPPER LEVEL LOW/TROF DESCENDING INTO PAC NW LATE THUR...STALLS IN
THE VICINITY THROUGH SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS AND 12Z UKMET/CMC BLEND
CONFIDENCE: AVERAGE

THE 12Z ECWMF SUITE IS A BIT STRONGER BRING MORE ENERGY TO
REINFORCE THE STALLING TROF ACROSS THE PAC NW BY FRI EVENING/SAT
MORNING...THIS APPEARS EVEN A BIT DEEP COMPARED TO AN OTHERWISE
FAIRLY TIGHT DETERMINISTIC AND NAEFS ENSEMBLE CLUSTER WITH ONLY
THE 00Z NAM UNDER INFLUENCES OF A STRONGER QUASI-STATIONARY UL
LIFTING BACK N/NW IN ALBERTA...DRAWS FALLING HEIGHTS ON SAT
FURTHER EAST.  AS SUCH WILL SUPPORT A 00Z GFS AND 12Z UKMET/CMC
BLEND AT AVERAGE CONFIDENCE FOR THIS SYSTEM.


UPPER LOW DRIFTING E OF FLORIDA WITH APPROACHING SURFACE WAVE
TRACKING N OF BAHAMAS FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: AVERAGE

DETERMINISTIC AND ENSEMBLE SUITE IS FAIRLY CONFIDENT IN MODESTLY
DEEP SYSTEM TRACKING NORTH OF THE BAHAMAS THUR/FRI WITH THE MAIN
AXIS JUST OFF THE FL COAST BY 12Z SAT WITH EXCELLENT AGREEMENT IN
TIMING OVERALL.  THE 00Z NAM IS A BIT MORE AGGRESSIVE (STRONG) AS
THE ONLY DETERMINISTIC RUN TO CLOSE OFF 1012MB SURFACE ISOBAR AND
MAINTAIN IT; THOUGH THIS IS A DOWNWARD SHIFT IN INTENSITY CLOSER
TO THE PACK. ALSO THE 12Z CMC IS GENERALLY SOUTH OF THE CONSENSUS
AND THE 00Z GFS/18Z GEFS ARE A BIT FURTHER NORTH.  GIVEN THE
SPREAD IS NOT TERRIBLY LARGE...SUPPORT AN OPERATIONAL MODEL BLEND
AT AVERAGE CONFIDENCE ATTM.


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

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

GALLINA

$$





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