Hurricane Sandy is already unleashing cyclone-force winds and mega waves teased higher by a full-moon, with high tides coming after 8 p.m. tonight in the New Jersey and New York City area. The storm is threatening roughly 50 million in the eastern third of the country, and could rank in the top ten worst of all hurricanes.

Weather analysts now say the storm surge energy figures may clock in bigger than Hurricane Katrina in 2005, though New Orleans is below sea level and was in a smaller area.

Still, Hurricane Sandy’s punch will be felt big time in flooding, from six-foot- to eleven-foot-high waves, and that means massive inland water breaks, with storm surges up to three inches higher due to the full moon.

Already, insurance analysts are assessing the cost of Hurricane Sandy, expecting much of the damage will likely be caused by the tidal surge. Hurricane/disaster loss modeling company Eqecat says Sandy is already responsible for about $10 billion to $20 billion in economic losses as of this hour.

However, flooding isn’t typically covered by insurance policies for homes and businesses. Consumers typically must buy separate insurance policies that cover damage from flooding due to high winds, or flooding from trees striking rooftops.

And it’s needed. Flooding is the country's top natural hazard, and was the main cause of damage in Hurricanes Katrina, Irene and Isaac, says the Federal Emergency Management Agency (FEMA).

Meanwhile, the Insurance Information Institute says its 2011 poll found that just 14% of homeowners had a flood insurance policy. Where was the lowest rate of flood coverage?

The Northeast, with just 5%, now sitting smack in the line of Hurricane Sandy.

Flood coverage can be bought from the federal government, and if you live in a high-risk flood area, mortgage lenders typically demand you buy flood insurance.

The average federal flood insurance policy costs less than $570 per year, according to the National Flood Insurance Program, with maximum coverage of $250,000.

Still, out-of-pocket expenses for hurricanes and flooding often trend higher than other deductibles, with up to $1,000 owed first before insurance kicks in.

Since 1980, weather events have killed 30,000 people in North America, caused $1.1 trillion of damage and imposed $510 billion of losses on insurers, says a recent study from insurer Munich Re. The costliest was Hurricane Katrina in 2005, with total insured losses for property damage of more than $41 billion and 1,322 lives lost.

COSTLIEST U.S. HURRICANES
Insured Losses

Hurricane         Year        Insured Property Damage

1 Katrina          2005        $41.1B
2 Andrew         1992        $15.5B
3 Ike             2008        $12.5B
4 Wilma           2005        $10.3B
5 Charley         2004        $7.5B
6 Ivan            2004        $7.1B
7 Hugo            1989        $4.2B
8 Rita            2005        $5.6B
9 Frances         2004        $4.6B
10 Irene          2011        $4.3B

Source: Insurance Information Institute

Elizabeth MacDonald joined FOX Business Network (FBN) as stocks editor in September 2007.
Follow Elizabeth MacDonald on Twitter @LizMacDonaldFOX.