Issued at 500 PM AST MON OCT 21 2013
000
WTNT43 KNHC 212035
TCDAT3
TROPICAL STORM LORENZO DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132013
500 PM AST MON OCT 21 2013
THE SATELLITE PRESENTATION OF THE CYCLONE HAS BECOME BETTER
ORGANIZED SINCE THIS MORNING. A CURVED BAND CONSISTING OF COLD-
TOPPED CONVECTION HAS LENGTHENED AND BECOME BETTER DEFINED...EVEN
THOUGH THE LOW-LEVEL CENTER OF THE CYCLONE IS EXPOSED AT THE
WESTERN TIP. IN ADDITION...A 1254 UTC ASCAT-A PASS HAD A COUPLE OF
34-KT WIND VECTORS EAST-SOUTHEAST OF THE CENTER. BASED ON THE
EARLIER ASCAT PASS...THE DEPRESSION IS UPGRADED TO A TROPICAL STORM
WITH AN INITIAL INTENSITY OF 35 KT.
THE ASCAT PASSES AND FIXES FROM VISIBLE SATELLITE IMAGERY TODAY HAVE
ALLOWED FOR A BETTER ASSESSMENT OF THE INITIAL MOTION WHICH IS
ESTIMATED TO BE 030/06...TO THE LEFT OF THE PREVIOUS ESTIMATE.
THE FORECAST PHILOSOPHY REMAINS THE SAME. LORENZO SHOULD BE STEERED
NORTH-NORTHEASTWARD AND THEN NORTHEASTWARD DURING THE NEXT DAY OR SO
AROUND THE NORTHWEST SIDE OF A MID-LEVEL RIDGE. AFTER THAT TIME...
THE CYCLONE SHOULD TURN EAST-NORTHEASTWARD ALONG THE SOUTHERN EDGE
OF NEARLY ZONAL FLOW NEAR 30N. THE NHC TRACK FORECAST IS ADJUSTED
SIGNIFICANTLY TO THE LEFT OF THE PREVIOUS ONE DUE TO A MORE
NORTH-NORTHEASTERLY INITIAL MOTION...AND IS JUST AHEAD OF THE
MULTI-MODEL CONSENSUS TO BETTER MATCH THE FASTER GFS/ECMWF
SOLUTIONS.
SOME INTENSIFICATION IS EXPECTED DURING THE NEXT DAY OR SO WHILE THE
CYCLONE IS OVER WARM WATERS AND IN THE DIFFLUENT FLOW EAST OF AN
UPPER-LEVEL CYCLONIC SHEAR AXIS. BY 36 HOURS...SHIPS OUTPUT SHOWS A
CONSIDERABLE INCREASE IN WESTERLY VERTICAL WIND SHEAR THAT SHOULD
RESULT IN A DECOUPLING OF THE CYCLONE IN 2 TO 3 DAYS. THE GUIDANCE
SHOWS THE REMNANT CIRCULATION IS LIKELY TO DISSIPATE AHEAD OF AN
APPROACHING BAROCLINIC ZONE IN 3 TO 4 DAYS. THE NHC INTENSITY
FORECAST IS RAISED SLIGHTLY OVER THE PREVIOUS ONE...AND IS
GENERALLY NEAR THE MULTI-MODEL CONSENSUS BUT A BIT LOWER THAN THE
SHIPS/LGEM OUTPUT.
FORECAST POSITIONS AND MAX WINDS
INIT 21/2100Z 28.9N 54.9W 35 KT 40 MPH
12H 22/0600Z 29.5N 53.9W 40 KT 45 MPH
24H 22/1800Z 29.9N 52.5W 45 KT 50 MPH
36H 23/0600Z 30.3N 51.1W 40 KT 45 MPH
48H 23/1800Z 30.9N 49.8W 35 KT 40 MPH
72H 24/1800Z 33.0N 46.5W 30 KT 35 MPH
96H 25/1800Z...DISSIPATED
$$
FORECASTER KIMBERLAIN
Continue reading...
000
WTNT43 KNHC 212035
TCDAT3
TROPICAL STORM LORENZO DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132013
500 PM AST MON OCT 21 2013
THE SATELLITE PRESENTATION OF THE CYCLONE HAS BECOME BETTER
ORGANIZED SINCE THIS MORNING. A CURVED BAND CONSISTING OF COLD-
TOPPED CONVECTION HAS LENGTHENED AND BECOME BETTER DEFINED...EVEN
THOUGH THE LOW-LEVEL CENTER OF THE CYCLONE IS EXPOSED AT THE
WESTERN TIP. IN ADDITION...A 1254 UTC ASCAT-A PASS HAD A COUPLE OF
34-KT WIND VECTORS EAST-SOUTHEAST OF THE CENTER. BASED ON THE
EARLIER ASCAT PASS...THE DEPRESSION IS UPGRADED TO A TROPICAL STORM
WITH AN INITIAL INTENSITY OF 35 KT.
THE ASCAT PASSES AND FIXES FROM VISIBLE SATELLITE IMAGERY TODAY HAVE
ALLOWED FOR A BETTER ASSESSMENT OF THE INITIAL MOTION WHICH IS
ESTIMATED TO BE 030/06...TO THE LEFT OF THE PREVIOUS ESTIMATE.
THE FORECAST PHILOSOPHY REMAINS THE SAME. LORENZO SHOULD BE STEERED
NORTH-NORTHEASTWARD AND THEN NORTHEASTWARD DURING THE NEXT DAY OR SO
AROUND THE NORTHWEST SIDE OF A MID-LEVEL RIDGE. AFTER THAT TIME...
THE CYCLONE SHOULD TURN EAST-NORTHEASTWARD ALONG THE SOUTHERN EDGE
OF NEARLY ZONAL FLOW NEAR 30N. THE NHC TRACK FORECAST IS ADJUSTED
SIGNIFICANTLY TO THE LEFT OF THE PREVIOUS ONE DUE TO A MORE
NORTH-NORTHEASTERLY INITIAL MOTION...AND IS JUST AHEAD OF THE
MULTI-MODEL CONSENSUS TO BETTER MATCH THE FASTER GFS/ECMWF
SOLUTIONS.
SOME INTENSIFICATION IS EXPECTED DURING THE NEXT DAY OR SO WHILE THE
CYCLONE IS OVER WARM WATERS AND IN THE DIFFLUENT FLOW EAST OF AN
UPPER-LEVEL CYCLONIC SHEAR AXIS. BY 36 HOURS...SHIPS OUTPUT SHOWS A
CONSIDERABLE INCREASE IN WESTERLY VERTICAL WIND SHEAR THAT SHOULD
RESULT IN A DECOUPLING OF THE CYCLONE IN 2 TO 3 DAYS. THE GUIDANCE
SHOWS THE REMNANT CIRCULATION IS LIKELY TO DISSIPATE AHEAD OF AN
APPROACHING BAROCLINIC ZONE IN 3 TO 4 DAYS. THE NHC INTENSITY
FORECAST IS RAISED SLIGHTLY OVER THE PREVIOUS ONE...AND IS
GENERALLY NEAR THE MULTI-MODEL CONSENSUS BUT A BIT LOWER THAN THE
SHIPS/LGEM OUTPUT.
FORECAST POSITIONS AND MAX WINDS
INIT 21/2100Z 28.9N 54.9W 35 KT 40 MPH
12H 22/0600Z 29.5N 53.9W 40 KT 45 MPH
24H 22/1800Z 29.9N 52.5W 45 KT 50 MPH
36H 23/0600Z 30.3N 51.1W 40 KT 45 MPH
48H 23/1800Z 30.9N 49.8W 35 KT 40 MPH
72H 24/1800Z 33.0N 46.5W 30 KT 35 MPH
96H 25/1800Z...DISSIPATED
$$
FORECASTER KIMBERLAIN
Continue reading...