Issued at 1100 AM AST WED SEP 19 2012
000
WTNT44 KNHC 191452
TCDAT4
TROPICAL STORM NADINE DISCUSSION NUMBER 33
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012
1100 AM AST WED SEP 19 2012
DEEP CONVECTION HAS BEEN GRADUALLY DECLINING AND IS BECOMING FARTHER
REMOVED FROM THE CENTER. AMSU DATA SHOWED A MID- TO UPPER-LEVEL
WARM CORE STRUCTURE...BUT THE LACK OF CENTRAL CONVECTION IS
INDICATIVE OF A DECAYING TROPICAL CYCLONE. DVORAK INTENSITY
ESTIMATES ARE 35 KT BUT SINCE THIS IS SUCH A MARGINAL TROPICAL
CYCLONE...THESE ESTIMATES MAY BE PROBLEMATIC. A RECENT ASCAT PASS
SHOWED THAT THE SYSTEM STILL HAD WINDS TO 45 KT. HOWEVER...IF THE
CURRENT CONVECTIVE TREND CONTINUES...NADINE WILL SOON NO LONGER
QUALIFY AS A TROPICAL OR SUBTROPICAL CYCLONE. THE OFFICIAL
FORECAST SHOWS THE SYSTEM BECOMING POST-TROPICAL IN 24 HOURS BUT
THIS TRANSITION COULD OCCUR EVEN EARLIER THAN THAT. THE INTENSITY
FORECAST MAINTAINS THE 45-KT INTENSITY FOR THE NEXT SEVERAL DAYS
SINCE THE POST-TROPICAL CYCLONE WILL PROBABLY FIND SOME SOURCES OF
BAROCLINIC ENERGY DURING THE FORECAST PERIOD.
THE MOTION IS BECOMING ERRATIC AND THE CURRENT ESTIMATE IS 020/04.
MOST OF THE BETTER-PERFORMING DYNAMICAL MODELS ARE IN GOOD AGREEMENT
THAT THE SYSTEM SHOULD SOON TURN TOWARD THE EAST-SOUTHEAST AS IT
BECOMES CAUGHT IN THE STEERING FLOW ON THE SOUTHWEST SIDE OF A
STRONG MID-TROPOSPHERIC TROUGH AND CUTOFF LOW OVER THE EASTERN
ATLANTIC DURING THE NEXT 48 HOURS OR SO. IN THE LATTER PART OF THE
FORECAST PERIOD...THE MODELS BECOME MORE DIVERGENT WITH THE U.K.
MET. OFFICE MODEL TAKING THE SYSTEM SOUTHWARD AND WESTWARD...THE
ECMWF SHOWING THE CYCLONE BECOMING ABSORBED...AND THE GFS MOVING
THE SYSTEM QUICKLY TOWARD PORTUGAL. AS A COMPROMISE...THE OFFICIAL
FORECAST MOVES THE CYCLONE SLOWLY EASTWARD FROM DAYS 3 TO 5. THIS
IS SIMILAR TO THE PREVIOUS NHC TRACK AND NOT FAR FROM THE DYNAMICAL
MODEL CONSENSUS.
FORECAST POSITIONS AND MAX WINDS
INIT 19/1500Z 37.2N 31.8W 45 KT 50 MPH
12H 20/0000Z 37.4N 31.4W 45 KT 50 MPH
24H 20/1200Z 36.6N 30.2W 45 KT 50 MPH...POST-TROPICAL
36H 21/0000Z 35.5N 28.4W 45 KT 50 MPH...POST-TROPICAL
48H 21/1200Z 34.5N 26.5W 45 KT 50 MPH...POST-TROPICAL
72H 22/1200Z 34.5N 23.5W 45 KT 50 MPH...POST-TROPICAL
96H 23/1200Z 34.5N 22.0W 45 KT 50 MPH...POST-TROPICAL
120H 24/1200Z 34.5N 21.0W 45 KT 50 MPH...POST-TROPICAL
$$
FORECASTER PASCH/ZELINSKY
Continue reading...
000
WTNT44 KNHC 191452
TCDAT4
TROPICAL STORM NADINE DISCUSSION NUMBER 33
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012
1100 AM AST WED SEP 19 2012
DEEP CONVECTION HAS BEEN GRADUALLY DECLINING AND IS BECOMING FARTHER
REMOVED FROM THE CENTER. AMSU DATA SHOWED A MID- TO UPPER-LEVEL
WARM CORE STRUCTURE...BUT THE LACK OF CENTRAL CONVECTION IS
INDICATIVE OF A DECAYING TROPICAL CYCLONE. DVORAK INTENSITY
ESTIMATES ARE 35 KT BUT SINCE THIS IS SUCH A MARGINAL TROPICAL
CYCLONE...THESE ESTIMATES MAY BE PROBLEMATIC. A RECENT ASCAT PASS
SHOWED THAT THE SYSTEM STILL HAD WINDS TO 45 KT. HOWEVER...IF THE
CURRENT CONVECTIVE TREND CONTINUES...NADINE WILL SOON NO LONGER
QUALIFY AS A TROPICAL OR SUBTROPICAL CYCLONE. THE OFFICIAL
FORECAST SHOWS THE SYSTEM BECOMING POST-TROPICAL IN 24 HOURS BUT
THIS TRANSITION COULD OCCUR EVEN EARLIER THAN THAT. THE INTENSITY
FORECAST MAINTAINS THE 45-KT INTENSITY FOR THE NEXT SEVERAL DAYS
SINCE THE POST-TROPICAL CYCLONE WILL PROBABLY FIND SOME SOURCES OF
BAROCLINIC ENERGY DURING THE FORECAST PERIOD.
THE MOTION IS BECOMING ERRATIC AND THE CURRENT ESTIMATE IS 020/04.
MOST OF THE BETTER-PERFORMING DYNAMICAL MODELS ARE IN GOOD AGREEMENT
THAT THE SYSTEM SHOULD SOON TURN TOWARD THE EAST-SOUTHEAST AS IT
BECOMES CAUGHT IN THE STEERING FLOW ON THE SOUTHWEST SIDE OF A
STRONG MID-TROPOSPHERIC TROUGH AND CUTOFF LOW OVER THE EASTERN
ATLANTIC DURING THE NEXT 48 HOURS OR SO. IN THE LATTER PART OF THE
FORECAST PERIOD...THE MODELS BECOME MORE DIVERGENT WITH THE U.K.
MET. OFFICE MODEL TAKING THE SYSTEM SOUTHWARD AND WESTWARD...THE
ECMWF SHOWING THE CYCLONE BECOMING ABSORBED...AND THE GFS MOVING
THE SYSTEM QUICKLY TOWARD PORTUGAL. AS A COMPROMISE...THE OFFICIAL
FORECAST MOVES THE CYCLONE SLOWLY EASTWARD FROM DAYS 3 TO 5. THIS
IS SIMILAR TO THE PREVIOUS NHC TRACK AND NOT FAR FROM THE DYNAMICAL
MODEL CONSENSUS.
FORECAST POSITIONS AND MAX WINDS
INIT 19/1500Z 37.2N 31.8W 45 KT 50 MPH
12H 20/0000Z 37.4N 31.4W 45 KT 50 MPH
24H 20/1200Z 36.6N 30.2W 45 KT 50 MPH...POST-TROPICAL
36H 21/0000Z 35.5N 28.4W 45 KT 50 MPH...POST-TROPICAL
48H 21/1200Z 34.5N 26.5W 45 KT 50 MPH...POST-TROPICAL
72H 22/1200Z 34.5N 23.5W 45 KT 50 MPH...POST-TROPICAL
96H 23/1200Z 34.5N 22.0W 45 KT 50 MPH...POST-TROPICAL
120H 24/1200Z 34.5N 21.0W 45 KT 50 MPH...POST-TROPICAL
$$
FORECASTER PASCH/ZELINSKY
Continue reading...