Post-Tropical Cyclone CALVIN

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POST-TROPICAL CYCLONE CALVIN DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032011
800 PM PDT SAT JUL 09 2011
 
INFRARED AND MICROWAVE SATELLITE IMAGERY INDICATE THAT CALVIN HAS
CONTINUED TO RAPIDLY DEGENERATE. THERE HAS BEEN NO ORGANIZED DEEP
CONVECTION NEAR THE LOW-LEVEL CENTER FOR NEARLY 9 HOURS NOW...AND A
09/2037Z AMSU OVERPASS INDICATED THAT THE UPPER-LEVEL WARM CORE HAD
DISSIPATED WITH ONLY A WEAK WARM CORE REMAINING NEAR THE 500 MB
LEVEL. ALTHOUGH A SMALL THUNDERSTORM WITH TOPS COLDER THAN -70C HAS
RECENTLY DEVELOPED ABOUT 70 NMI SOUTHWEST OF THE CENTER...THIS
CONVECTION IS LIKELY NOT PROVIDING ANY POSITIVE FEEDBACK ON THE
INNER CORE OF THE LOW. AS A RESULT...CALVIN HAS BEEN DECLARED A
NON-CONVECTIVE REMNANT LOW PRESSURE SYSTEM. THE INITIAL INTENSITY
IS SET AT 30 KT BASED ON AN EXPECTED SPINDOWN OF 35-40 KT WINDS
THAT WERE NOTED IN AN EARLIER 09/1734Z ASCAT SATELLITE OVERPASS.

THE INITIAL MOTION ESTIMATE IS 285/09. THE REMNANT LOW IS EXPECTED
TO MOVE SLOWLY WEST-NORTHWESTWARD OVER COLDER WATER FOR THE NEXT 2
DAYS AS THE CIRCULATION REMAINS EMBEDDED IN SHALLOW LOW-LEVEL
EASTERLY TRADE WIND FLOW. GIVEN MUCH COOLER WATERS AND MORE STABLE
AIR AHEAD OF THE REMNANT LOW...REDEVELOPMENT OF ANY ORGANIZED DEEP
CONVECTION NEAR THE LOW-LEVEL CENTER IS UNLIKELY.

12-FT SEAS RADII HAVE BEEN INCLUDED SINCE CALVIN ONLY RECENTLY LOST
ITS STATUS AS A TROPICAL CYCLONE...AND IT WILL TAKE A FEW MORE
HOURS FOR THE SEAS TO SUBSIDE.
 
THIS IS THE FINAL NHC ADVISORY ON CALVIN. FOR ADDITIONAL INFORMATION
ON THE REMNANT LOW...PLEASE SEE HIGH SEAS FORECASTS ISSUED BY THE
NATIONAL WEATHER SERVICE...UNDER AWIPS HEADER NFDHSFEPI AND WMO
HEADER FZPN02 KWBC.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/0300Z 17.7N 112.6W   30 KT  35 MPH
 12H  10/1200Z 18.0N 113.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 24H  11/0000Z 18.5N 115.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 36H  11/1200Z 19.0N 116.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  12/0000Z 19.5N 118.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  13/0000Z...DISSIPATED
 
$$
FORECASTER STEWART
 
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