Severe weather event beginning to unfold

[jkt21787]

The severe weather event expected today is starting. Three severe thunderstorm watches have been issued, from OK to MO, then back to IL.
Several severe thunderstorm and a few tornado warnings are already in effect.

Squall line is developing, but is broken as of now. This is leading to embedded supercells with a threat of isolated tornadoes. Strong wind shear will allow rotating storms with these cells.

The line should consolidate as it moves east, reaching the MS river by early Thursday morning. Damaging winds remain the main threat, but isolated tornadoes are possible. Hail is unlikely, but could occur in some areas, especially in the ARKLATEX north to the Ozarks.

More info as it develops tonight. Stay tuned.

[jkt21787]

A few more things to add...

Instability remains limited, due to limited sunshine as expected. However, there will be enough instability to support severe weather, especially the squall line. This will be because of very strong jet dynamics and wind energy. Lots of wind shear with helicity over 500 m2/s2 will lead to the tornadic potential within embedded supercells, as is occurring now.

As the squall line continues to form, bow echoes could become more common, and create areas of widespread wind damage. Wind speeds of 60 to 70 mph and locally higher possible. Keep in mind the very strong winds a few thousand feet higher in the atmosphere, it won't take much to bring these wind gusts down to the surface.

Specifically for the Memphis area and Mid-South, I believe the line will cross the river sometime between Midnight and 6 AM, depending on the speed. Very likely that some parts of the line will still be severe, with bowing segments, and a tornadic cell or two is possible. Heavy rain also expected, but no major flooding.

[jkt21787]

A new watch has been posted for central and western AR, Northern LA, and Northeast TX. It is for severe thunderstorms. The line is developing southward and is slowly intensifying. The most concentrated severe weather is in the ozarks. A few tornado warnings continue.

Intresting development: some cells are forming in northeast arkansas east of Little Rock and south of Jonesboro. They are looking rather intense on radar. Could this be the start of something intresing? I doubt it as of now, but certainly that area should be watched. Will at least see some downpours, lightning, and gusty winds with it.

[NCSUWX23]

A new watch has been posted for central and western AR, Northern LA, and Northeast TX. It is for severe thunderstorms. The line is developing southward and is slowly intensifying. The most concentrated severe weather is in the ozarks. A few tornado warnings continue.

Intresting development: some cells are forming in northeast arkansas east of Little Rock and south of Jonesboro. They are looking rather intense on radar. Could this be the start of something intresing? I doubt it as of now, but certainly that area should be watched. Will at least see some downpours, lightning, and gusty winds with it.

Still looking unlikely that the Carolinas will see any thunderstorms, let alone severe Thursday night into Friday morning. It looks like just alot of heavy rain.

[PurdueWx80]

If the mini-supercells near and north/east of Little Rock can maintain themselves in light of the capping, they will likely become tornadic given southeast surface flow, temps in the low 70's and dewpoints in the low to mid 60's. Instability won't really increase, but the capping should decrease as the upper low makes it's way towards AR. There are some nasty supercells embedded in the line across MO and IL right now and also points south from there. Still think quickly spun up tornadoes will be a good bet in the lower/mid MS and lower OH valleys along this line. If those supercells in AR sustain themselves, a tornado watch will likely be issued in the next hour or two.

[jkt21787]

So far, the cells in AR aren't holding up well as the cap remains strong, though one cell remains in the searcy area. As the cap begins to weaken, this could become an active area.

The wind profiles are very favorable for mini supercells and tornadoes if they do in fact become sustained, although right now no major development is occurring.

The squall line is continuing to organize itself from DFW up to STL, even with a threat into IL/IN now! Some embeded supercells also continue in southwest missouri back towards IL as you mentioned, with another area southeast of Fort Smith trying to become more pronounced.

Several areas to watch over the next few hours.

[jkt21787]

After looking at some radar, that cell over Searcy arkansas is concerning. There is a small hook trying to form within it. There is no pronounced low level rotation but there is mid level rotation upwards of 35kts. It is a very low topped, mini supercell. Will have to watch it to see if it can maintain itself.

[jeff]

Damaging squall line developing from C TX to N Ill this evening along and just ahead of a strong trough and cold front. Cap is breaking along the south end of the line with local NEXRADS showing rapidly increasing thunderstorms from Dallas S to Austin. Line is already well congealed over E OK and N AR and again over ILL and moving E at about 30mph.

Damaging winds will be the main threat with gust of 90mph or greater within bows and microburst. Widespread 50-60mph winds will be common along the entire line. Isolated tornadoes are possible with discrete supercells ahead of the line and embedded within the line. Lack of instability should limit the tornadic threat, however a few F0 and F1 tornaodes will be possible especially over AR, LA and E TX.

Intense squall line will run E overnight through AR into MS and TN. The line will gradually weaken Thursday on the northern end with the severe threat shifting south to along the Gulf coast and over AL.

As this line approaches your location, move away from W and NW facing windows and walls. Strong winds may result in structural damage from this direction.

Jeff L

[jkt21787]

Severe weather continues to develop, especially in AR and LA. Two new severe thunderstorm watches stretch from NE TX to IL that will continue into the overnight hours. The squall line has really organized in the last hour in AR and LA, with some embedded supercells capable of isolated tornadoes. With strong wind shear continuing, the severe weather threat remains. Even though instability is lacking, there is just enough in combination with the wind shear to keep the severe weather threat up. The squall line will continue east overnight reaching the MS river by 3 to 6 AM, then moving into the TN Valley and gulf coast states.

Damaging winds in excess of 60 and perhaps 70 mph are possible. Some damage is already being reported in Central and Northern Arkansas. Even though severe thunderstorm watches are in effect, a few tornadoes are still possible in isolated cells ahead or in the line that break away from the main convection. Heavy rainfall is also becoming a bigger issue, especially in MO and NW AR, and some flash flooding is possible. The hail threat will be near zero, some a couple of reports are not out of the question.

Continue to keep up to date with the latest watches and warnings. If you are going to sleep, keep a weather radio, TV or radio nearby in order to receive any possible warnings.