Meteorological history 1996 Lake Huron cyclone

map plotting track , intensity of storm, according saffir–simpson scale

on september 11, 1996, weak low-pressure area situated close lake superior. near surface, central pressure 1,012.0 hectopascals (29.88 inhg) on lake michigan. there shortwave @ 500 hpa level (18,000 ft above mean sea level) on ontario. northwest tilt of low height indicated surface center in stage of baroclinic development. in addition this, analysis concluded cyclone had cold core in mid-troposphere. analysis @ 700 (around 10,000 ft above mean sea level) , 850 millibar (around 5,000 ft above mean sea level) pressure levels indicated cyclone had cold core within lower troposphere.

the cyclone s overall strength increased, surface winds building 11 mph (18 km/h) 67 mph (108 km/h). occurred while positive vorticity , thermal advection causing moderate rain showers on ontario, broken area of thunderstorms present ahead of advancing cold front. september 12, cyclone moved southward position on lake huron, upper portions centered west on michigan. during 24-hour period, cyclone s central pressure fell 1,012.0 hectopascals (29.88 inhg) 1,006.0 hectopascals (29.71 inhg). after 1200 utc september 12, low moved southeastward , became vertically stacked surface 500 millibar pressure surface (located 18,000 ft above mean sea level).

for brief time, portions of cyclone @ 300 , 200 mbar pressure levels moved southeastward on lake huron. greatest intensification occurred below 500 mbar level. cyclone s tilt neutral, or stacked height, storm in occlusion (or warm seclusion) stage of cyclone development. cyclone proceeded through stage, cold front, connected surface low, became occluded front caught surface warm front. occluded front extended lake huron pennsylvania on september 13. 155-mile (250 km) swath of showers , thunderstorms positioned across frontal zone. @ time, third area of showers centered near occluded low.

between 1200 utc on september 13 , 0000 utc on september 14, shortwave rotated throughout area of occluded low. caused mid-level portion of cyclone move eastward, centering east of lake huron. during same period, surface low moved on lake huron , fell 5 more millibars 999.0 hectopascals (29.50 inhg). in response change, maximum sustained winds increased well. after 0000 utc september 14, lower , mid-tropospheric portions of cyclone moved westward, becoming stacked atop 1 again, time through 200 mbar pressure level. in contrast earlier developments, baroclinicity of system diminished rapidly. however, lower tropospheric area continued intensify, dropping 993.0 hectopascals (29.32 inhg), major height falls seen aloft. lowered baroclinicity determined heat fluxes may have spawned intensification. @ time of peak intensity, cyclone had maximum sustained winds of 73 miles per hour (117 km/h), equivalent of powerful tropical storm.

between 1200 utc on september 14 , 0000 utc on september 15, visible satellite imagery of vortex revealed resemblance tropical cyclone, eye-like feature 19 miles (30 km) wide. in addition eye, convective clouds had formed, creating eyewall resembling of tropical cyclone. furthermore, feeder bands of convective showers continued extending westward 310 miles (500 km). after cyclone passed buoy 45008, winds turned east-northeast , rapidly increased. in contrast earlier period of storm s life, had more energy in high levels (like cold-core low), system stronger near surface (similar warm-core low). surface analysis indicated weaker cyclonic circulation persisted on eastern shore of lake huron, center north of lake ontario. during 12-hour period, cyclone diminished rapidly, in lower troposphere. twelve-hour cloud height rises occurred, ranging 66–197 feet (20–60 m). on september 15, cyclone decayed , left lake huron.