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Ice storm cripples Houston; Yasi the 2nd costliest Australian storm on record

By: Dr. Jeff Masters, 4:13 PM GMT on February 04, 2011

A significant ice storm is in progress across southeast Texas, much of Louisiana, northern Mississippi, and southern Arkansas this morning, as the latest onslaught from the memorable winter of 2010 - 2011 continues. Houston, Texas recorded 1/10" - 1/4" inch of ice so far from the storm, resulting in a crippling of that city's transportation system. Numerous crashes have closed many area roads, and flights at local airports have been largely halted. Snowfalls of 1 - 3 inches will occur today along the northern edge of the ice storm region, in a swath from northeast Texas to western Kentucky. The storm will move into New England on Saturday, but will not bring heavy snow. The next chance for heavy snow occurs next Wednesday and Thursday, when the GFS model is predicting the formation of a winter storm capable of dropping a foot of snow in the Appalachians and inland areas of New England. However, it is too early to put much faith in this forecast.

Figure 1. Trees snapped off along the Chicago lakefront by winds from the Blizzard of 2011. Image credit: viewer uploaded photo from WGN.

Revisiting the Chicago blizzard
This week's blizzard in Chicago dropped 20.2" of snow on the city, Chicago's third-greatest snowstorm on record. But the tremendous winds that accompanied the blizzard--gusting to 61 mph at O'Hare Airport, and 70 mph at the Lakefront--made the storm Chicago's worst-ever blizzard as far as impacts on travel. Another remarkable feature of the storm were the intense thunderstorms that developed. According to an excellent write-up on the storm posted by the Chicago National Weather Service office, the Blizzard of 2011 had 63 lightning strikes, and several reports of hail. The most extraordinary hourly observation I've ever seen in a U.S. winter storm came at 9:51pm on February 1 at Chicago's Midway Field: A heavy thunderstorm with lightning, heavy snow, small hail or ice pellets, freezing fog, blowing snow, visibility 300 feet, a wind gust of 56 mph, and a temperature of 21°F. Welcome to the Midwest! Thanks go to meteorologist Steve Gregory for pointing this observation out to me.

Figure 2. Snow amounts from the February 1 - 3 blizzard of 2011 peaked at over 2 feet along the shore of Lake Michigan between Chicago and Milwaukee. Strong northeasterly winds pulled moist air off of the Lake in this region, allowing the "lake effect" to enhance the blizzard's snows in this region. Image credit: Chicago National Weather Service office.

Tropical Cyclone Yasi the second most damaging storm in Australia's history
Tropical Cyclone Yasi has dissipated, but the damage totals from the storm make it Australia's second most expensive tropical cyclone of all-time, according to Tropical Storm Risk, Inc. The storm's $3.5 billion price tag is second only to Cyclone Tracy, which hit Darwin on Christmas Day 1974, doing $3.6 billion in damage (2011 dollars.) Yasi roared inland over Queensland, Australia at 12:30am local time on Thursday as a strengthening Category 4 storm with 155 mph winds and a 930 mb central pressure. The cyclone missed the most populous cities on the coast, Cairns and Townsville, but damaged up to 90% of the buildings in the small towns near where the eye passed--Tully, Mission Beach, and Cardwell. A storm surge of 5.4 meters (17.7 feet) was observed at Cardwell, and there was substantial surge damage at the coast. Fortunately, the storm surge hit near low tide, resulting in a storm tide--the height of the water above land--of about 4.5 meters, more than 2 meters below what would have occurred had Yasi hit at high tide. Yasi moved quickly enough across Queensland after landfall so that major flooding was limited to just three locations near the coast. Yasi's central pressure of 930 mb at landfall made the storm the most intense recorded in Queensland since at least 1918, and possibly since 1899. In 1918, there were two cyclones (at Mackay and Innisfail) with measured pressures in the upper 920s/low 930s, but it is quite plausible that the minimum central pressures were lower than that. The 1899 (Mahina/Bathurst Bay) cyclone had a measured pressure (ship near shore) of 914 mb.

Figure 3. The tide gauge at Carwell, Australia during passage of Tropical Cyclone Yasi recorded a 5.4 meter (17.7') storm surge (red line). Since the surge came near low tide, the storm tide--the height of the surge above mean water--was only 4.5 meters (blue line). The storm tide would have been more than 2 meters higher had Yasi hit at high tide, and the damage from coastal flooding would have been huge. The green line shows the expected water levels at Cardwell due to the tide. Image credit: Queensland government.

Figure 4. Tropical Cyclone Yasi at 04:15 UTC February 3, 2011, as seen by NASA's Aqua satellite.

Jeff Masters
Yasi Damage Tully Nth Qld
Yasi Damage Tully Nth Qld
Butler St Tully Nth Qld
Chicago Blizzard 2011
Chicago Blizzard 2011
Digging out....over 20 inches of snow and drifts in the 3 to 5 foot range.
Snow Drifts in Central Missouri
Snow Drifts in Central Missouri
Looking outside our front door in Columbia, MO.
Ice dams are forming, not good for water infiltrating walls

Winter Weather Hurricane

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