Severe Weather Event March 8-9, 2011

During this time of year it is not surprising to have a severe weather event and then a few days later have another one.  The last weather event was over the weekend where Louisiana got the brunt of it all with 4 tornadoes and a bunch of wind reports.  The only thing about the last storm event is that it was very limited to the instability it needed to create severe weather with the except of Louisiana.  This next event, however, is looking to be a little different than the last.  Here is what SPC is showing so far for the area to keep an eye on. 
A good sized area is highlighted for a slight change of severe weather and this shows even with the probabilities of severe weather occurring, but it is kind of misleading because of the 30% area that is hatched.  The hatched area inside the 30% means that there is 10% or greater of significant severe weather that could occur.  Since that area has a higher probability of seeing severe weather then I would monitor Louisiana, southwestern Arkansas, extreme northeastern Texas, and extreme southeastern Oklahoma.  I would not be surprised to see this area under a moderate risk of severe weather by tomorrow morning which will increase the possibilities of severe weather to occur in that area.  If you would like to read the details on why this area is being monitored heavily then visit http://www.spc.noaa.gov/products/outlook/day2otlk.html.

Since the above convective outlook starts from 12Z Tuesday (6 AM CST Tuesday) and ends at 12Z Wednesday (6 AM CST Wednesday) we will look at the forecast surface charts for that time period to show what is forecast to happen. 
This is at 6 AM CST Tuesday morning and the important things to look for on this is the surface low in the panhandle of Texas, the fronts and dry line connected to it, and the stationary front north of the surface low.  Ahead of the warm front is where the showers and thunderstorms will be occurring and even along the dry line is another area.  Kansas will be under the gun around this time as it is north of the surface low that will enhance precipitation of both rain and snow due various lifting mechanisms and temperature variability.  Lets move 6 hours ahead to 12 PM CST (noon). 
The low has slowly, but gradually moved towards the northeast keeping all of its fronts.  The difference is the moisture distribution.  Now there is a lot of moisture and precipitation being lifted and moved from the Gulf of Mexico into the Southern Mississippi Valley and Central Great Plains regions.  These are the areas that are being heavily monitored for severe weather to occur.  What may cause the chances for the severe weather?  The winds are a big factor for chances of tornadoes.  Winds in the middle layers of the atmosphere are westerly winds while the ones near the surface are from the southeast during this time period.  Two opposing winds can cause rotation and create tornadoes.  Lets move on and see how this event continues to evolve in the next 6 hours. 
This is showing the same situation but further east into Mississippi into southern Illinois.  This will be next area to watch for into Tuesday evening for severe weather that could cause wind, hail, and tornadoes.  The chances will most likely not be as high as the other areas, but are still just as likely to occur.  Finally, lets look on to the last 6 hours of the time period. 
Now into Wednesday morning and the system has pushed into Alabama stretching into Ohio and Indiana.  At this time the system is most likely going to be produce heavy rain with a small chance of severe weather to occur.  Tornadoes are highly not likely to occur at this time because the winds in the middle and low levels of the atmosphere are pretty much parallel which does not favor rotation, but hail and strong winds are still likely to happen.

This may seem like another severe weather event to embrase for, but it isn't all about tornadoes, damaging winds, and hail.  There is another important factor that is just as likely to happen in this event that happened last weekend and that's flooding.  There are a lot of places that are very prone to flooding right now due to them being large cities with no way to handle lots of heavy rain or due to rivers and streams that are at or near floodstage.  Here is the forecasted amount of rain to fall starting from Monday evening at 6 PM CST and ending at 6 PM CAST Wednesday. 
There is a bullseye of heavy precipitation in southestern Louisiana, southeastern Mississippi, and southern and central Alabama along with northern Georgia.  These are all areas with 2.5" and greater of precipitation to fall.  With these amounts flash flooding is possible and flooding from rivers and streams are also very likely which explains why there are so many flood warnings and watches of various kinds already in effect according to the following map that shows the current hazards. 
All of those shades of greens are all pertaining to some type of flood issue that is likely to occur by Wednesday.

Overall, This is something to really watch for and to monitor closely.  I will keep you posted and updated tomorrow as the event draws nearer to the Southeast Region.