WTNT43 KNHC 311432
TCDAT3
TROPICAL STORM CHANTAL DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032007
1100 AM EDT TUE JUL 31 2007

VISIBLE SATELLITE IMAGES INDICATE THAT CHANTAL HAS STRENGTHENED THIS
MORNING WITH IMPRESSIVE CURVED BANDING ESPECIALLY IN THE NORTHERN
SEMICIRCLE.  THE LOW-LEVEL CENTER OF THE STORM APPEARS TO BE
DISPLACED TO THE SOUTHEAST OF A CLEARLY IDENTIFIABLE MID-LEVEL
CENTER ON SATELLITE.  A QUIKSCAT PASS JUST BEFORE 1000 UTC SHOWED
BELIEVABLE WIND VECTORS IN THE 40-45 KT RANGE AND THE INITIAL
INTENSITY WILL BE SET TO 45 KT.  THE TROPICAL CYCLONE IS QUICKLY
MOVING INTO COOLER WATERS AND LITTLE ADDITIONAL INTENSIFICATION AS A
TROPICAL CYCLONE IS EXPECTED.  GLOBAL COMPUTER MODELS SUGGEST THAT
CHANTAL WILL BECOME THE MAIN PART OF A LARGE POWERFUL LOW OVER THE
NORTHERN ATLANTIC OCEAN AND A LITTLE ADDITIONAL BAROCLINIC
STRENGTHENING IS SHOWN IN A COUPLE DAYS.  

THE STORM IS MOVING RAPIDLY NORTHEASTWARD AT ABOUT 25 KT.  THIS
GENERAL MOTION...WITH SOME ACCELERATION...IS EXPECTED FOR THE NEXT
DAY OR TWO AS CHANTAL IS STEERED BY A DEEPENING MIDDLE-LATITUDE
TROUGH OVER NORTHEASTERN CANADA.  THE TRACK GUIDANCE IS IN GOOD
AGREEMENT ON THIS SCENARIO AND THE OFFICIAL FORECAST IS BASICALLY
AN UPDATE OF THE PREVIOUS FORECAST.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/1500Z 40.2N  62.7W    45 KT
 12HR VT     01/0000Z 43.0N  59.7W    45 KT
 24HR VT     01/1200Z 47.0N  52.7W    45 KT...EXTRATROPICAL
 36HR VT     02/0000Z 51.2N  44.7W    50 KT...EXTRATROPICAL
 48HR VT     02/1200Z 56.0N  36.0W    50 KT...EXTRATROPICAL
 72HR VT     03/1200Z 60.0N  27.5W    50 KT...EXTRATROPICAL
 96HR VT     04/1200Z 62.0N  20.0W    45 KT...EXTRATROPICAL
120HR VT     05/1200Z 64.5N  12.5W    40 KT...EXTRATROPICAL
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 312030
TCDAT3
TROPICAL STORM CHANTAL DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032007
500 PM EDT TUE JUL 31 2007

CHANTAL IS MAINTAINING A CURVED BAND STRUCTURE ON VISIBLE SATELLITE
PICTURES...ALBEIT WITH LESS DEEP CONVECTION THAN EARLIER TODAY. 
THE STORM SHOULD SOON BEGIN THE EXTRATROPICAL TRANSITION PROCESS AS
SEA SURFACE TEMPERATURES BENEATH THE STORM SOON DECREASE BELOW 70F
AND IT INTERACTS WITH COOLER AIR OVER THE CANADIAN MARITIMES. 
SATELLITE CLASSIFICATIONS AND AMSU INTENSITY ESTIMATES SUPPORT
MAINTAINING THE INITIAL INTENSITY OF 45 KT.  COMPUTER
MODELS...ESPECIALLY THE GFS...FORECAST THE SYSTEM TO BECOME A
STRONG EXTRATROPICAL STORM IN ABOUT 3 DAYS AND A LITTLE
STRENGTHENING IS INDICATED AT THAT TIME.  

CHANTAL CONTINUES TO MOVE NORTHEASTWARD...WITH A 12 HOUR MOTION OF
ABOUT 23 KT.  A DEEPENING MIDDLE-LATITUDE STORM OVER EASTERN CANADA
SHOULD CONTINUE THE STORM'S MOTION TOWARD THE NORTHEAST WITH SOME
ACCELERATION.  MODEL GUIDANCE IS TIGHTLY CLUSTERED ON A TRACK
TAKING THE SYSTEM NEAR OR OVER THE AVALON PENINSULA OF NEWFOUNDLAND
AND THE OFFICIAL FORECAST REFLECT THIS SCENARIO.  

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/2100Z 41.7N  61.2W    45 KT
 12HR VT     01/0600Z 44.5N  57.3W    45 KT...BECOMING EXTRATROPICAL
 24HR VT     01/1800Z 48.6N  49.7W    45 KT...EXTRATROPICAL
 36HR VT     02/0600Z 53.5N  40.5W    45 KT...EXTRATROPICAL
 48HR VT     02/1800Z 57.0N  34.5W    45 KT...EXTRATROPICAL
 72HR VT     03/1800Z 60.0N  27.5W    50 KT...EXTRATROPICAL
 96HR VT     04/1800Z 62.0N  19.0W    40 KT...EXTRATROPICAL
120HR VT     05/1800Z 64.0N  12.0W    35 KT...EXTRATROPICAL
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 010232
TCDAT3
TROPICAL STORM CHANTAL DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032007
1100 PM EDT TUE JUL 31 2007
 
SATELLITE IMAGERY SUGGESTS THAT CHANTAL IS RAPIDLY BECOMING
EXTRATROPICAL.  THE CONVECTIVE BAND THAT WAS WRAPPING AROUND THE 
CENTER DURING THE AFTERNOON HAS WEAKENED THIS EVENING.  SATELLITE
INTENSITY ESTIMATES CONTINUE TO SUPPORT AN INITIAL INTENSITY OF 45
KT.  AS CHANTAL PASSED VERY NEAR BUOY 44912 AROUND 2300 UTC...THE
BUOY REPORTED A MINIMUM PRESSURE OF 995.1 MB.  THE GLOBAL MODELS
SUGGEST THAT THE SYSTEM WILL INTENSIFY INTO A POWERFUL
EXTRATROPICAL LOW OVER THE NORTH ATLANTIC DURING THE NEXT 2-3 
DAYS.  

THE INITIAL MOTION ESTIMATE IS 045/28.  THE TRACK GUIDANCE IS
TIGHTLY CLUSTERED ON A NORTHEASTWARD MOTION DURING THE DAY OR SO. 
ON THIS TRACK...EXTRATROPICAL CHANTAL IS EXPECTED TO PASS OVER OR
VERY NEAR THE AVALON PENINSULA OF NEWFOUNDLAND IN ABOUT 12 HOURS. 
BEYOND 72 HOURS...THE MODEL SPREAD IS MUCH GREATER...WITH THE ECMWF
SHOWING A SLOWER MOTION THAN EITHER THE GFS OR NOGAPS.  THE
OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ADVISORY AND IS NEAR THE
GFS GLOBAL MEAN ENSEMBLE.

THIS IS THE LAST ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON
CHANTAL.  ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN
HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER
AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      01/0300Z 43.6N  58.5W    45 KT
 12HR VT     01/1200Z 46.6N  53.6W    45 KT...EXTRATROPICAL
 24HR VT     02/0000Z 51.7N  45.1W    45 KT...EXTRATROPICAL
 36HR VT     02/1200Z 56.0N  37.0W    50 KT...EXTRATROPICAL
 48HR VT     03/0000Z 57.9N  32.3W    60 KT...EXTRATROPICAL
 72HR VT     04/0000Z 60.0N  25.0W    50 KT...EXTRATROPICAL
 96HR VT     05/0000Z 62.0N  16.5W    40 KT...EXTRATROPICAL
120HR VT     06/0000Z 65.5N   8.0W    35 KT...EXTRATROPICAL
 
$$
FORECASTER BROWN
 

