Update: Possible Cyclone Formation Alert: Madagascar

WTXS21 PGTW 280130
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT REISSUED//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/270121Z FEB 12//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT (WTXS21 PGTW
270130)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 090 NM EITHER SIDE OF A LINE FROM 16.0S 45.1E TO 17.3S 41.2E WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 22 TO 28 KNOTS. METSAT IM-AGERY AND SYNOPTIC DATA AT 272330Z INDICATE THAT A CIRCULATION CENTER IS LOCATED NEAR 16.1S 45.2E. THE SYSTEM IS MOVING WEST-SOUTHWESTWARD AT 07 KNOTS. 2. REMARKS: ANIMATED INFRARED SATELLITE IMAGERY SHOWS CONVECTION BEING SHEARED SHARPLY TO THE WEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE LLCC IS SKIRTING THE COASTLINE OF NORTHWEST MADAGASCAR AND CONVECTION HAS EBBED IN RESPONSE TO THE LAND INTERACTION. RECENT SCATTEROMETRY DATA INDICATES THAT THE LLCC IS BROAD, WITH A SMALL REGION OF 25-30 KNOT SOUTHERLIES OVER THE OPEN WATERS OF THE CHANNEL. THE 271200Z PGTW UPPER LEVEL STREAMLINE ANALYSIS DEPICTS THE LLCC UNDER A REGION OF HIGHLY DIFFLUENT EASTERLIES, BUT FAR ENOUGH NORTH OF THE SUBTROPICAL RIDGE AXIS THAT THE SHEAR IS IMPEDING DEVELOPMENT. RECENT ANIMATED WATER VAPOR IMAGERY SHOWS SOME MILD IMPINGEMENT TO OUTFLOW OVER THE SOUTHWESTERN QUADRANT ALONG WITH A LACK OF ANY WELL-DEVELOPED OUTFLOW CHANNELS. TOTAL PRECIPITABLE WATER LOOPS INDICATE INCREASING DEEP MOISTURE IN THE MOZAMBIQUE CHANNEL. A LOW- TO MID-LEVEL ANTICYCLONE NORTH OF MADAGASCAR HAD BEEN RETROGRADING SOUTHWEST AND DRIVING THE LLCC SOUTHWESTWARD TOWARDS A A REGION OF REDUCED VERTICAL WIND SHEAR, BUT THE STEERING INFLUENCE OF THE ANTICYCLONE APPEARS TO BE WANING. THE SYSTEM IS BECOMING TRAPPED BETWEEN STRONG LOW- TO MID-LEVEL ANTICYCLONES ON EITHER SIDE OF MADAGASCAR, WHICH WILL CONFINE IT BETWEEN THE 16TH AND 19TH LATITUDES. SEA SURFACE TEMPERATURES NEAR THE CAPE SAINT ANDRE REGION ARE 29 TO 30 DEGREES. FURTHER DEVELOPMENT OF THE SYSTEM IS LIKELY AS THE LLCC TRACKS DEEPER INTO THE MOZAMBIQUE CHANNEL. MODEL GUIDANCE IS CONSISTENT IN INDICATING EASTWARD MOVEMENT WITH FURTHER INTENSIFICATION.

- JTWC + CIMSS