Saturday, October 13, 2012

Flash Flooding Possible Overnight

Many models are projecting amounts of rainfall that would create quite a flash flooding problem overnight. Let's take a look into this potential.

The 12z WRF model is projecting many spots to surpass the 4 inch mark, something that may set a challenge to sewer systems of less populated towns. Like the Gulf Coast, the general population tends to believe that since New Orleans has a powerful levee system, the entire Gulf Coast is now safe from flooding because every other town on the coast has the same powerful levee system. Not the case- many towns have levee systems that are miniscule in comparison to New Orleans. In this case, many believe that, since Chicago and St. Louis have big sewer systems, flash flooding won't happen. For more rural towns and some suburbs, the threat of flash flooding is much more of a problem, as their sewer systems are not as advanced as bigger cities'.

The 39 hour total precipitation forecast from the 12z NAM puts many of the same areas under 4 to 5 inches of possible rain- a huge feat for many sewer systems. Models vary greatly on final rainfall totals, but even the possibility of more than one model presenting such a big number is something that is quite alarming.

If you follow the Lezak Recurring Cycle, you will have to watch this system- it may very well come back in early December!


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