000
WTNT43 KNHC 200247
TCDAT3

TROPICAL STORM CHRIS DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032012
1100 PM AST TUE JUN 19 2012

CHRIS IS PRODUCING A CURLED...COMPACT AREA OF DEEP CONVECTION THAT
IS DISPLACED JUST TO THE EAST AND SOUTHEAST OF THE LOW-LEVEL
CENTER.  TAFB AND SAB PROVIDED DVORAK ESTIMATES OF 35 KT...AND THE
LATEST UW-CIMSS ADT IS ABOUT 40 KT.  SINCE THE OVERALL ORGANIZATION
HAS CHANGED LITTLE SINCE THIS AFTERNOON...THE INTENSITY WILL BE
HELD AT 40 KT.

CHRIS IS EMBEDDED WITHIN A DIGGING MID- TO UPPER-LEVEL TROUGH...SO
IT IS NOW MOVING TOWARD THE EAST-SOUTHEAST AT A FASTER SPEED...OR
110/11 KT.  A CLOSED LOW IS FORECAST TO DEVELOP AT THE NORTHERN END
OF THE TROUGH OVER THE NEXT 24 TO 48 HOURS...WHICH WILL ENHANCE THE
MID-LATITUDE WESTERLY FLOW AND CAUSE CHRIS TO FURTHER ACCELERATE
TOWARD THE EAST AND EAST-NORTHEAST THROUGH EARLY THURSDAY.  AFTER
THE LOW CLOSES OFF AND STALLS...CHRIS WILL BEGIN TO LOOP
CYCLONICALLY AROUND THE LOW BY 48 AND 72 HOURS.  THE TRACK MODELS
ALL AGREE ON THIS SCENARIO.  THE GFS AND ECMWF LIE ON THE WESTERN
SIDE OF THE ENVELOPE WHILE THE GFDL AND HWRF LIE ON THE EASTERN
SIDE.  GIVEN THE MID-LATITUDE ENVIRONMENT...THE NHC FORECAST LEANS
MORE HEAVILY TOWARD THE GLOBAL MODEL SOLUTIONS.  DISSIPATION IS
FORECAST BY 96 HOURS WHEN CHRIS SHOULD BE FULLY ABSORBED WITHIN THE
CLOSED LOW.

THE GLOBAL MODEL GUIDANCE DOES NOT PROVIDE A CLEAR-CUT ANSWER OF
WHEN EXTRATROPICAL TRANSITION WILL END.  THE FSU PHASE-SPACE
DIAGRAMS BASED OFF THE GFS SUGGEST THAT THE THERMAL STRUCTURE WILL
BECOME INCREASINGLY ASYMMETRIC WITH A SHALLOWER WARM CORE DURING
THE NEXT 24 HOURS.  THEREAFTER...THE DIAGRAMS INDICATE THAT CHRIS
WILL AGAIN DEVELOP A DEEPER WARM CORE...BUT THIS MOST LIKELY IS
REPRESENTATIVE OF AN EXTRATROPICAL WARM SECLUSION.  ON THIS
BASIS...CHRIS IS FORECAST TO BE FULLY EXTRATROPICAL BY 36 HOURS.
DUE TO RELATIVELY COOL SEA SURFACE TEMPERATURES AND MODERATE
VERTICAL SHEAR...CHRIS IS EXPECTED TO CHANGE LITTLE IN STRENGTH
UNTIL IT BECOMES EXTRATROPICAL AND FEEDS OFF BAROCLINIC ENERGY
ASSOCIATED WITH THE CLOSED MID/UPPER-LEVEL LOW.


FORECAST POSITIONS AND MAX WINDS

INIT  20/0300Z 38.8N  56.0W   40 KT  45 MPH
 12H  20/1200Z 38.7N  52.9W   40 KT  45 MPH
 24H  21/0000Z 39.5N  48.4W   40 KT  45 MPH
 36H  21/1200Z 41.4N  44.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
 48H  22/0000Z 43.7N  43.8W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  23/0000Z 44.5N  45.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  24/0000Z...ABSORBED BY ANOTHER EXTRATROPICAL LOW

$$
FORECASTER BERG

000
WTNT43 KNHC 200839
TCDAT3

TROPICAL STORM CHRIS DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032012
500 AM AST WED JUN 20 2012

CHRIS CONTINUES TO PRODUCE A COMMA-SHAPED BAND OF HEAVY SHOWERS THAT
IS WRAPPING AROUND THE NORTHERN AND EASTERN PORTION OF THE
CIRCULATION.  GIVEN THAT THE SATELLITE-OBSERVED STRUCTURE OF THE
STORM HAS SHOWN LITTLE CHANGE AND DVORAK INTENSITY ESTIMATES ARE
ALSO UNCHANGED SINCE THE PREVIOUS ADVISORY...THE CURRENT INTENSITY
IS MAINTAINED AT 40 KT.  CHRIS WILL BE MOVING OVER RELATIVELY COOL
WATERS AND IN AN ENVIRONMENT OF MODERATE SHEAR FOR THE NEXT DAY OR
SO...SO LITTLE CHANGE IN STRENGTH IS FORECAST FOR THE EARLY PART OF
THE FORECAST PERIOD.  BY 36 HOURS...THE GLOBAL MODELS INDICATE THAT
THE CYCLONE WILL BECOME INVOLVED WITH A FRONTAL ZONE SO
EXTRATROPICAL TRANSITION IS FORECAST TO OCCUR AROUND THAT TIME.
SOME SLIGHT INTENSIFICATION DUE TO BAROCLINIC PROCESSES IS POSSIBLE
WITHIN A COUPLE OF DAYS.  HOWEVER...LATER IN THE FORECAST PERIOD...
THE POST-TROPICAL CYCLONE IS FORECAST TO WEAKEN AND MERGE WITH
ANOTHER EXTRATROPICAL CYCLONE OVER THE NORTH ATLANTIC.

THE FORWARD MOTION HAS ACCELERATED TO 100/15.  THE CYCLONE IS
EMBEDDED WITHIN AN AMPLIFYING MID-TROPOSPHERIC TROUGH...AND A
CLOSED LOW IS DEVELOPING OVER THE NORTHERN PORTION OF THIS TROUGH.
CHRIS SHOULD ACCELERATE EASTWARD TO EAST-NORTHEASTWARD AROUND THE
SOUTHERN PORTION OF THE LOW TODAY...AND AFTERWARDS THE POST-TROPICAL
CYCLONE IS LIKELY TO CURVE CYCLONICALLY AROUND THE EASTERN AND
NORTHERN PORTIONS OF THE LOW.  THE OFFICIAL FORECAST IS FAIRLY
CLOSE TO THE LATEST DYNAMICAL MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INIT  20/0900Z 38.2N  53.5W   40 KT  45 MPH
 12H  20/1800Z 38.3N  50.4W   40 KT  45 MPH
 24H  21/0600Z 39.6N  45.7W   40 KT  45 MPH
 36H  21/1800Z 42.0N  42.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
 48H  22/0600Z 44.0N  43.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  23/0600Z 44.0N  45.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  24/0600Z...MERGED WITH ANOTHER EXTRATROPICAL LOW

$$
FORECASTER PASCH

000
WTNT43 KNHC 210250
TCDAT3

TROPICAL STORM CHRIS DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL032012
1100 PM AST WED JUN 20 2012

CHRIS HAS HAD WHAT COULD BE CONSIDERED AN EYE FOR THE PAST SEVERAL
HOURS.  HOWEVER...SUBJECTIVE AND OBJECTIVE SATELLITE INTENSITY
ESTIMATES DO NOT SUPPORT ANY SIGNIFICANT CHANGE IN STRENGTH.  THE
MAXIMUM WINDS ARE THEREFORE BEING KEPT AT 50 KT.  EVEN IF CHRIS IS
A LITTLE STRONGER...THE CYCLONE IS NOW MOVING OVER SEA SURFACE
TEMPERATURES LESS THAN 22C...AND THE MARINE BOUNDARY LAYER COULD BE
TOO STABLE TO ALLOW STRONGER WINDS TO BE MIXED TO THE OCEAN
SURFACE.

THE INITIAL MOTION IS 075 DEGREES AT 19 KT...AND CHRIS WILL LIKELY
BEGIN TO DECELERATE AND LOOP COUNTERCLOCKWISE WHILE INTERACTING
WITH A DEVELOPING UPPER LOW TO ITS NORTH.  THERE IS VERY LITTLE
DISPARITY BETWEEN THE TRACK MODELS OVER THE NEXT COUPLE OF DAYS.
THE GLOBAL MODELS ALSO SEEM TO AGREE THAT CHRIS WILL BE ABSORBED BY
OR MERGE WITH ANOTHER EXTRATROPICAL LOW BY 72 HOURS.

THE POST-TROPICAL TRANSITION IS THE TRICKIEST PART OF THE FORECAST.
THE FSU PHASE SPACE DIAGRAMS STILL ARGUE THAT CHRIS WILL DEVELOP A
DEEPER WARM CORE OVER THE NEXT FEW DAYS.  HOWEVER...THE GFS FIELDS
SHOW CHRIS BEGINNING TO INTERACT WITH A FRONTAL BOUNDARY TO ITS
NORTH IN ABOUT 24 HOURS...ENDING UP ON THE COLD SIDE OF THE
BOUNDARY BY 48 HOURS.  CHRIS COULD BECOME POST-TROPICAL SOMETIME
OVER THE NEXT 24 HOURS IF IT LOSES ITS DEEP CONVECTION...AND IT
SHOULD BE INVOLVED WITH THE FRONT ENOUGH TO BE EXTRATROPICAL BY 36
HOURS.

THE INTENSITY IS EXPECTED TO CHANGE LITTLE OVER THE NEXT 24 HOURS.
GRADUAL WEAKENING SHOULD START WHEN CHRIS BECOMES EXTRATROPICAL.


FORECAST POSITIONS AND MAX WINDS

INIT  21/0300Z 38.9N  46.4W   50 KT  60 MPH
 12H  21/1200Z 40.3N  43.6W   50 KT  60 MPH
 24H  22/0000Z 43.0N  42.1W   50 KT  60 MPH...POST-TROPICAL
 36H  22/1200Z 44.5N  43.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
 48H  23/0000Z 43.8N  45.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  24/0000Z...ABSORBED BY ANOTHER EXTRATROPICAL LOW

$$
FORECASTER BERG

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