My thinking based on current material:
A slow moving cold front currently impacting areas of Texas north into Iowa will slowly move east through the week. Right now [ 11:12 AM EDT 3/19/2012 ] storms are beginning to fire along the front with the potential for severe weather including damaging winds, large hail and tornadoes. Severe thunderstorm and tornado watches will likely be issued at some point this afternoon for areas in Texas and points north.
Current Map March 19
The low pressure responsible for this front will according to models become a closed upper level low. Until this happens it will continue to pull colder air from the north and warm air from the south, leading to an unstable air mass. Once the low closes off it will continue to draw warm moist air from the gulf of Mexico region. This warm moist air combined with daytime heating will then provide the opportunity for strong storms to continue developing over the next few days through Wednesday as the front ever so slowly moves east through Louisiana. There is the potential for some of these storms to become severe where damaging winds, hail and even a tornado can not be ruled out.
Wednesday March 21
By Thursday morning the cold front will be in or around Western Mississippi with the upper level low remaining back in Oklahoma. At this time there is still the potential for strong to severe storms but to a lesser degree from previous days. During daytime heating some of these storms will have the potential to turn severe where again damaging winds, hail and even a tornado can not be ruled out.
Thursday March 22
By Friday morning the cold front will be in or around western Alabama. The closed upper level low will by then have moved slightly east into the Missouri area. To the south in Alabama areas of showers with possible storms developing during daytime heating will be the rule. Some of the stronger storms may have the potential to become severe. As this is 4 days away it is unclear how the storm system will continue to evolve so we’ll have to watch this.
Friday March 23
Farther to the north in areas of Tennessee, Kentucky, Indiana and Ohio things may be a little more interesting during this same time. While the cold from continues to trail from Indiana south through Alabama, a weak warm front will have continued to push north. Also of interest in an occluded front trailing back to the upper level low back in Missouri. This will create and area for potential strong to severe storms as the cold air overtakes the warm sector. Also of note in this area will be the different wind profiles or wind direction in which a quick spin up tornado cant be ruled out.
By Saturday morning the cold front will be pushing through Georgia, western areas of North and South Carolina continuing north through the Virginia’s. The upper level low at this time will be positioned in or around Indiana or Ohio. By this time most of the energy will have been lost and things should be relatively quite from North Carolina southward. To the North in Virginia it may still be a little unsettled with strong thunderstorms still possible.
Saturday March 24
All of the above is provided things remain true to current modeling and thinking. I’ll continue watching this system throughout the week and should things change will post an update.
Here’s a look at the potential rainfall associated with this system beginning Today March 19 thru Saturday morning March 24.