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