Monday, March 9, 2015

Our Spring Floods

One month to the day (May 3rd, 1978) after I started at Ch. 8,  New Orleans had the first of our great “100 year floods”.  We had several more during the 80s and then the biggest one in May of 1995.  There is a simple reason some of our biggest rains occur in the warmer months.  Warmer air has a higher capacity to hold water vapor.   Basically, the higher the temperature, the higher the amount of water (precipitable water) that can be suspended as vapor.   That is why on a hot (90+) summer day, we can get a downpour that leaves 2-3” in less than an hour.   That doesn’t happen during the colder months of the year.   We really haven’t reach the time of the year for the super heavy downpours, however, the “training effect” can cause heavy totals if it lasts for several hours.  One such episode happened today over Gulfport that left them with nearly 3” (2.91).  Computer models indicate several strong disturbances will rotate over us during the next 2-3 days bringing the possibility of 4-6”+ causing some minor street flooding.   If we were one month later (April), I’d be more concerned about higher totals.  Still, this looks to be a rainy stretch that will last most of this week.  The good news is no real cold air is in sight and we are nearing the end of our last freeze date.   Might be time to go plant dem tomaters.


Tomorrow night I’ll talk about the rising Mississippi with all the snow melt up North.

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