Dangerous Category 4 Hellen Nears Madagascar

Extremely dangerous Category 4 Tropical Cyclone Hellen is bearing down on Madagascar after an extraordinary burst of rapid intensification brought the cyclone from a 60 mph tropical storm to a high-end Category 4 storm with 150 mph winds in just 24 hours. That 90 mph increase in winds in 24 hours is not far below the record intensification rate of Hurricane Wilma in 2005, which was 110 mph in 24 hours. Official bulletins from La Réunion indicate the central pressure dropped 61 mb in 24 hrs, from 986mb at 1800 UTC Saturday to 925mb at 1800 UTC Sunday. They warn in their 18 UTC Sunday advisory:

HELLEN IS LIKELY TO BE ONE OF THE MOST POWERFUL TROPICAL CYCLONES EVER SEEN OVER THE NORTHERN CHANNEL SINCE THE SATELLITE ERA (1967). THE LIKELIHOOD IS INCREASING FOR AN EXTREMELY DANGEROUS TROPICAL CYCLONE LANDFALL OVER THE NORTHWESTERN COASTLINE OF MADAGASCAR BETWEEN CAPE SAINT-ANDRE AND MAHAJONGA. THE RSMC TROPICAL CYCLONE STORM SURGE NWP HAS BEEN RUN AND SHOWS PHENOMENAL SEA ELEVATIONS IN THE AREA EXPOSED TO THE NORTHERLY WINDS (EAST OF THE FORECAST TRACK). THE STORM SURGE COULD REACH 2 - 4 METERS (7 - 13 FEET) IN THE ESTUARY OF THE BETSIBOKA RIVER (MAHAJONGA), AND MORE THAN 7 METERS (23 FEET) IN THE BAY OF BALY (SOALALA), AND 1 - 4 METERS ON THE COASTLINE EAST OF CAPE SAINT-ANDRE. ALL PREPARATIONS FOR A "WORST CASE" SCENARIO SHOULD BE UNDERWAY.


Figure 1. True-color MODIS satellite image of Tropical Cyclone Hellen nearing Madagascar at 12 UTC March 29, 2014. At the time, Hellen was a Category 4 storm with 150 mph winds. Image credit: NASA.

Jeff Masters