5/10/2006 FCST: AR/KY/TN/TX/LA/MS/AL

[Brandon Clement]

Tomorrow has a lot of potential and a few question marks. The GFS and NAm show a deepenign low moving from the Northern plains into Mo. North Ms and Tn seem to be in the best areas where 2500-3500 Mlcape will be present combined with deep layer sheer 40-50 knots. Models are showing the MCS from todays convection moving through in the morning hours leaving a nice outflow boundary. Daytime heating will allow temps to climb into the mid 80's with td's around 70 yielding nice LCL's.

Storm initiation should occur over central Ar and move across the Ms into where 0-3 SRH values will exceed 300 and winds become more backed at the surface. There are still two huge unknowns:

1) Storm mode. Storms will initiate as supercells but are expected to move into a line. How quickly the storms become linear will greatly affect the type of severe weather. If they can stay discrete when moving into Ms they will encounter ideal conditions to become tornadic.

2) Ongoing MCS. Is it going to strip the airmass or will the rapid return verify? Where will the outflow boundary set up? Will it clear out of the area to allow plenty of time for the daytime heating to take place?


The terrain in the areas from Eastern Ar, West Ms, Southwest Tn and the Mo bootheel are all ideal chase terrain. If things continue to come together I would be very suprised if it wasn't a high risk. I will decide on a target tomorrow morning since I am only a few hours away but if I had to pick a target now it would be Greenville, Ms where I can cross into Ar if needed, will have ideal terrain, nice road network and plenty of good terrain to my East.

PS: I am not a meteorologist but I did stay at a Holiday Inn Express last night. If I am wrong on anything please jump right in.

 

[Nick Parker]

Im with Brandon on the potential for tomorrow. Solid clouds in So. Ill right now. Interesting to see how long tonights weather will hold with us in the morning. Definatly have the moisture for sure. After glancing at a few items, (havent been online long <_< ) I would bank on that they'll hold supercellular "format" for at least most of the afternoon, just depending on the exact time they do decide to "pop". Screwed either way on this one....rain has shut the soybean planting down, but does give the oppurtunity to chase a bit B) (Make no money but burn lots of 15 mpg fuel)

Good luck and safe travel to all tomorrow!
Nick

 

[tom hanlon]

I feel that Wednesday is likely to see some severe weather. The question is not so much "if" but "where".

Tonights convection and the resulting cold pool will have some effect. Heating and cloud cover will also have some effect. Storms evolving in the lower shear environment and heading east into more favorable environnment East of the mississippi and wether or not they remain discrete supercells or are linear in nature.

These factors prevent a well defined bullseye target at the moment. I suppose we will have to wait till the morning and see what the evening leaves us.

Even in the morning it will likely be rather uncertain and dependent on development of surface heating as the day goes by.

I suppose I will get a few hundred miles closer and see what happens.

--
Tom Hanlon

 

[Paul Knightley]

Looking at the current obs, which show a strong outflow boundary aligned E-W across central MS, and the expected CAPE (in excess of 4000 J/KG, perhaps 5K!), I would favour hanging (for my virtual chase - only a week to go until the real thing!) around Winona, MS, or perhaps a little west of there, in order to be close to the boundary, as it lifts north.

 

[Brandon Clement]

Still some big questions regarding the MCS over Ar. Hopefully it hits the capped air over Ms and rapidly dissipates and we can get the heating started. Just spoke with Ken Johnson and we both agree that supercell developement is going to be explosive today with gorilla hail and large, long lived tornadoes likely. Biggest concern is the cap breaking all at once and not allowing some storms to remain discrete which tends to happen here in Ms more often than not. I really like the area in central and East Ms but will sacrifice the slightly better conditions for West Ms where terrain is wonderful. Hopefully I don't regret this later. Current target is Greenville, Ms. I will leave out about 10 to be in place shortly after noon. I don't expect storms to fire until later in the afternoon but I want to be in place when the show starts.

Another area that I think could be a potential blockbuster is N. La between Vicksburg and Monroe. If the current MCS does infact weaken quickly it should leave another nice boundary draped across the I-20 corridor in La curving northward along the Ms river but this is just me speculating.

Good luck to anyone chasing today and if your on the fence about today's setup it could be the last good chase day for quite some time. Also the Eastern Ar, West Ms delta region is as good a chase terrain as there is in the country just a much smaller scale.

 

[Brandon Clement]

Extremely difficult forecast today and would love to hear some thoughts.

Currently both MCS have been strenghtening and look to be stripping the energy in the west Ms/Tn and East Ar areas. A strong boundary is running E-W across Ms, Al and Ar. The boundary is acting somewhat like a warm front and is keeping storms from firing farther to the south while holding the instability in place. Farther to the SE in central La some clearing has started. Looking at the water vapor images drier air from the southwest is helping maintain a stronger cap from Shreveport to areas south. Basically the dry air in the mid level is streaming in and running into the MCS in Arkansas not allowing it to expand southward. The MCS is not weakening and pushing off to the ESE. The instability is being completely stripped by the MCS in Ar and I don't think the airmass can recover since the front is so close behind. My thoughts are now shifting towards central La NE into the Jackson area. Significant tornado index is now 5 across south central La and all the elements are in place. As of now I am just going to try and hold off on leaving until I get a better idea of how things will play out.

I would really love to hear some feedback/thoughts from some more experienced forecasters.

 

[tom hanlon]

I am trying to figure out what the SPC sees in the state of indiana that I am missing.

The more promising activity further south is beyond my reach and I assume that this thread covers this whole system. So... what is going on in Indiana ?

I guess if we get a tiny bit of instability and some storms then the rest of the pieces are already in place such as extremely low LCL, shear, etc. Usually with this much cloud cover at 4 PM I would head home. But the SPC is tenaciously hung on to a 10% tor for much of Indiana. I have been in KY all day and have not seen one drop of sunshine. Arkansas has some clear areas perhaps some advection from that area.

Who knows.... feels like a bust in what was the northern section of the MOD/SLIGHT risk today but I will wait it out.

--
Tom Hanlon

 

[rdale]

I am trying to figure out what the SPC sees in the state of indiana that I am missing. [/b]

Same thing I'm missing up here! I was surprised when yesterday they popped us up to 15%, then more shocked when the 20Z outlook brought it back again... No wind support, high freezing level, junk storms - not seeing any good threat in this part of the Great Lakes.

 

[Jason Hetzel]

Wouldnt the process of rapid cyclogenesis have anything to do with this? I think this is what SPC is looking at. Seeing as how this would create a very nice favorable wind shear environment for tornadic low topped cells to form however i agree with horrible instability being in place and my guess is that SPC is watching the cloud breaks in SE MO at this time and basing their guess off of that. CAPE values are really low, even in that area with only 500 J/Kg. I wonder how this will play out as we go further into the evening but never the less it should be interesting to see how it unfolds...

 

[rdale]

The 15% hail line took a good thousand mile jump south with the 01Z report ;> Still have a TOR/WIND threat up here - and I still can't see why... This looks to be a quiet night through the MI / n OH / n IN sections.