03/01/07 FCST: AR / MO / KY / TN / AL / IL / MS

[Brett Adair]

Well, it seems that I am in the center of the MDT risk area here in Talladega County, Alabama (Southern) I'm thinking that supercells are going to go west of here and my plan has been from the get go to intercept over near TCL. Talked with a few other chasers last night and it seems that we could be having a convention this time tomorrow morning over that way at around 10AM. I personally look to go ahead and setup at around 9am CST tomorrow morning. It looks like supercells may go not too long after that. Anyone that is interested.....there is a Wings with a wifi hotspot about 2 miles north of I-20/59 off of exit 73A? in Tuscaloosa. I should be sitting in the parking lot in a green Montero for a while if anyone would like to join me. Looks like an interesting day folks...

 

[Donald Giuliano]

Hmm, hadn't been paying much attention to tonight/Thursday prior to someone mentioning SPC's moderate. After a cursory glance, it looks pretty scary to me. It looks eerily similar to the pattern in place May 4, 2003, in terms of in the extent of surface instability (though not magnitude), lack of CINH (I recall a remarkable lack of CINH over the entire warm sector that day), and the placement of upper-level features:

*Eta analysis valid 00z 5 May, 2003*
http://weather.unisys.com/archive/eta_init/0305/03050500.gif

*24hr NAM forecast valid 12z Mar 1, 2007*
http://weather.unisys.com/nam/24h/nam_4panel_24h.html

Very interesting, and very worrisome for folks living in the risk areas, especially since a lot of this could occur at night.

 

[P. Creedon]

Looks like the time frame for these, will be from 1 AM to 9 AM in my area. Now, should I head out, or will these be squall line crap by the time they get in my neck of the woods.

 

[George Tincher]

The new 1730z Day 2 just came out and all I have to say is WOW! That is one of the largest moderate risks I have ever seen, as well as perhaps the largest area I have ever seen outlined with 45% hatched probabilities. They also indicate that some portion of the current moderate risk may be UPGRADED TO HIGH RISK in later outlooks.

As I expected, the moderate risk area was pulled farther N. I am sure the only reason it wasn't last night was simply caution on the part of SPC forecasters who wanted to be sure conditions really would be that favorable for significant severe that far N.

Forecast CAPE over the more NRN areas of the outlook region still appear to be very minimal. But with the big dynamics, you can't ignore this area.

Areas farther S however look to have better CAPE (forecast MLCAPE values of 500-1000 J/KG over much of the area). I really have to wonder if CAPE may be underforecast by the models. The ETA (sorry, I still haven't evolved to say NAM yet...hehe) for tomorrow afternoon is showing temps in the 70's (approaching 80 over the SRN most areas of the outlook), with dewpoints well into the 60's. Cloud cover and cooling rain is obviously the issue. But I suspect there will be adequate clearing, at least in smaller pockets if not larger ones, that will find increased values of CAPE. Pair that up with impressive 0-1km shear and 0-6km shear and I think those storms tomorrow across the south are really gonna be big, bad and nasty.

 

[Skip Talbot]

http://grib2.wxcaster.com/wxcaster4/MIDWEST_WRF_1000-500_SLPTHKPRP_30HR.gif

Check out this 18Z WRF plot. Those look like supercell tracks to me, and that 974mb low is impressive. Does anyone have any experience with this model? I don't, so I don't know how well to gauge its reliability.

http://grib2.wxcaster.com/wxcaster4/MIDWEST_WRF_ATMOS_CAPE_30HR.gif

That CAPE plot is significantly greater than the other NAM plots.

Regardless of the model, I'm thinking Carbondale at 18z. SPC is saying that the storms are a continuation of overnight activity, so things will be well underway by that hour. I think if you were to chase this, however, you better wait until cells make it over decent terrain. With storm motions over 45 knots I would stay close to the interstates, 70 and 55, and intercept after they cross the MS. The precip plot has activity south of there at 18z and earlier in MO, but I think its going to be extremely frustrating trying to go after any of that. The bootheel is decent, but your storms won't stay there long.

 

[Andrew Pritchard]

I may be more geographically biased, but I agree with Skip as well. I think the best area for any discrete supercells producing tornadoes is going to be from MO to IL to IN during the day. Up here you are right next to the low and the warm front so surface winds are much better. Clear skies ahead of the system should also lead to doable instability. Down south in AL/TN/MS and such, I think there will be tornadoes and widespread severe weather, but I think it will be much more linear. Sure there will be tornadoes, but good luck seeing them in a wall of wind and rain. Not saying you shouldn't try though!

 

[George Tincher]

Skip, that is extremely interesting. I am actually buying those CAPE numbers more so than some of the others I have seen. It appears the band of higher SBCAPE (farther N anyway) will be pretty narrow. But seeing SBCAPE values in the range of 1500 and approaching 2000 all the way from SRN IL to the MO Bootheel is pretty darn impressive, especially when combined with the shear that will be available. Thank you for posting those links. That has really grabbed my attention.

Oh, FWIW, that looks like it was generated by the WRF. I haven't had very much experience using that one either, but here's some basic info about it:

http://www.wrf-model.org/index.php

I don't mean to sidetrack the forecast discussion with a secondary discussion abour particular models, so I will leave this at that. Perhaps we could open another thread in W&C to discuss it further? I too would like to learn more about that particular model from people who used it quite a bit.

 

[rdale]

The WRF runs 4x per day in the NAM slot from NCEP... Many people still call it the Eta mistakenly.

 

[Justin Bailey]

well this sucks. why couldn't this wait til friday when i dont have classes. college really gets in the way sometimes. i would love to head into W Ill tomorrow but wont be able to leave BG til 2:30 due to classes. i dont want to play with these monsters in the W KY hills so im most likely goin to have to sit this one out. looks like a very rough day for much of the mid ms vly and all of the south. i just gave my family in Paducah, Dyersburg, Tn., St. Louis, Nashville, and Augusta, SC all the heads up. this is one of the most widespread MDT i've seen! It'll be intersting to see how big the HIGH is tomorrow! i have no doubt this will be the first HIGH for 2007.

 

[Justin E. Reed]

Well, I made a model run, this is a very significant tornado outbreak that will occur. All models and all field, the TTs are off the charts, the super computer here bogged down because it was processing so much and there is no question that we will have over 2 dozen tornadoes. Eerily similar to May 4, 2003 as many have mentioned, This is probably the best chance to see tornadoes since 2003, sure we had April 7th, but most were not large tornadoes, this has the capabilities to produce prolific, long tracked, large tornadoes. My greatest concern is for BHM, MEM, BNA, JAN, FFC(ATL), PAH, and LZK(Little Rock). Everyone go ahead and get ready to go chasing, I might just have to cross into Srn GA for this one.

 

[Jeff Miller]

there is no question that we will have over 2 dozen tornadoes.

Justin, nice analysis and I agree on the intensity of the storm, but I would be careful in saying there is "no question" of 2 dozen or more tornadoes. I'm not saying this is out of the realm of possibility, just to make that definate to me seems too strong a prediction.

In your defense Justin, a look at the sigtor really opens the eyes to the power of this situation. (SIGTORS over 7(!)), Craven SigSvr 50-60, and EHI suggesting Strong Tornadoes (3.3). Severe paramaters look very favorable yes, and it looks to be quite dangerous to say the least. I believe there will be significant tornadoes, but still early as many variables can and probably will change - for good - or for bad.

 

[Andrew Pritchard]

Well, I made a model run, this is a very significant tornado outbreak that will occur. All models and all field, the TTs are off the charts, the super computer here bogged down because it was processing so much and there is no question that we will have over 2 dozen tornadoes. Eerily similar to May 4, 2003 as many have mentioned, This is probably the best chance to see tornadoes since 2003, sure we had April 7th, but most were not large tornadoes, this has the capabilities to produce prolific, long tracked, large tornadoes. My greatest concern is for BHM, MEM, BNA, JAN, FFC(ATL), PAH, and LZK(Little Rock). Everyone go ahead and get ready to go chasing, I might just have to cross into Srn GA for this one.

You do mean the best chance to see tornadoes in the southeast region since 2003, right?

With the linear nature in that region, and storm motions likely exceeding 50 mph, seeing tornadoes is not going to be "easy" in any way.

I do believe this will be an active day but I'm not quite ready to jump on the end of the world everythings off the charts bandwagon with some people yet. There are some concerns. Up north in Illinois and Indiana shear is better, but moisture is a concern. Down south moisture is better, but shear is not. Where you have the better moisture, the shear is more unidirectional which means most of your tornadoes are going to be hidden so even if you get in position to intercept a fast moving storm, the odds of seeing a tornado will be smaller.

 

[Jeff Snyder]

I agree about hesitation. If you've been forecasting severe weather for more than a couple of years, you've surely seen situations that look incredible yet don't pan out. I've seen several days that looked like they'd support a tornado outbreak, only be end up being days with garbage storms or linear mode (diminishing the tornado threat). I would strongly caution against saying that anything WILL or WILL NOT occur, especially if you are guaranteeing it. Of course, everyone has their right to their forecast, and this should remind those int he general public to refer to their official source of severe weather in life-theatening situations.

That said, I do agree with the Day 2, though I'm not quite as bullish. If instability ends up being a little more robust than forecast, then I'll rise my threat expectation accordingly. At this time, there does appear to be the risk for strong/violent tornadoes, but I think there'll be some dependence upon available instability and maintaining favorable storm mode (e.g discrete supercells).

 

[Andrew Pritchard]

I agree about hesitation. If you've been forecasting severe weather for more than a couple of years, you've surely seen situations that look incredible yet don't pan out. I've seen several days that looked like they'd support a tornado outbreak, only be end up being days with garbage storms or linear mode (diminishing the tornado threat). I would strongly caution against saying that anything WILL or WILL NOT occur, especially if you are guaranteeing it. Of course, everyone has their right to their forecast, and this should remind those int he general public to refer to their official source of severe weather in life-theatening situations.

That said, I do agree with the Day 2, though I'm not quite as bullish. If instability ends up being a little more robust than forecast, then I'll rise my threat expectation accordingly. At this time, there does appear to be the risk for strong/violent tornadoes, but I think there'll be some dependence upon available instability and maintaining favorable storm mode (e.g discrete supercells).

Exactly my point... with fear of straying too far from a forecast post I will leave it at this. Just think about as recently as all the November 2005 outbreaks we had. Specifically November 15th I believe it was. That day was compared the super outbreak by many before it happened. While there were many tornadoes with the system, how many people saw any? Me, and several others were within one HALF mile of an F1 tornado and saw nothing but rain.

These big systems don't always pan out to be huge events, and when they do, nothing is gauranteed as far as seeing anything.

 

[Jim Cross]

The tale of 2 choices.Either stay just east of the st.louis metro area as discussed early or go for the bootheel of missouri.The st.louis area is closer to the low and closer to home,but i like the better moisture and decent enough cape in the bootheel.I will be leaving for the caruthersville area in southeast missouri either later this evening or very early tomorrow morning.You have the river crossing there and your options to go north towards paducah or drop south out of dyersbug towards jackson.If anyone else is considering chasing this area as well leave me a message.Any thoughts about my choice of the bootheel over the st.louis metro area.