Severe Weather Event...South

[CYCLONE MIKE]

Thanks Jeff. I am sure you will have a much better idea tomorrow as to what areas could have the best chance of severe weather. I will look foward to your posts tomorrow as the time comes.

[Shoshana]

I'll tell you how its playing out in Travis County .... we just had a severe thunderstorm roll through north Austin with pea-sized hail at my house. Larger golf ball size hail further south towards downtown. Radar at 9:50 p.m. is showing a possible tornado in eastern Travis County moving east.

Fast moving storms but they pack a punch!

We had pea sized hail in NE Austin too.

'shana

[jeff]

TX:

Severe thunderstorms ongoing this morning north of surface frontal boundary over N and C TX. Nasty line has develop along the dry line over SW TX. Continued moisture advection and much weakening of the cap overnight should support SB develop by late morning.

This afternoon:

Trough ejecting into TX will force surface low pressure over SE TX and this should be the focal point for development of severe wx/ tornado outbreak. 140kt jet max, increasing LLJ, waekening cap, and strong instability support violent thunderstorm development. CAPE of 2000+ by early afternoon and cooling mid levels will support strong develop over SE TX by late afternoon. Degree of capping is still a bit uncertain, but given the degree of development over SW TX this morning the cap can probably be broken N of I-10.

MS Valley:

Very unstable warm sector will exist by later afternoon as surface low moves from SE TX toward C LA. Increasing lift, high CAPE and high shear profiles support clusters of supercells along and south of the warm frontal boundary. 0-1 km shear of 30kts and 0-3 km helicity of 150-250 M^2/S^2 will support updraft rotation. Low LCL's and very moist envirnoment along with strong shear will support tornadoes a few which may be very strong.

Greatest tornado threat is from SC LA across most of MS and most of AL. Some areas may be hit multiple times as storms continue to develop within WAA ahead of surface low/ cold front. Supercells will continue through the evening and overnight hours. Similar events in the past have produce many injuries and deaths across the south during the overnight.

Storms will also fire along the cold front from SE TX across LA this evening and form into a squall line or MCS. Damaging winds and very large hail will be the main threats with this activity, although a few tornadoes will be possible.

I may not be around this afternoon, as I may head NW for a little chasing

JL

[Brent]

Looks like it's going to be a LONG night here.

[Portastorm]

Good luck to you folks in the deep South and stay safe!

We're under the gun again here in central Tx with some heavier weather out west moving towards our area. Doesn't look as intimidating as last night though. Regardless, I picked a lousy day to smoke a brisket!

[jeff]

New weather watch expected E and S of WW 85 early this afternoon.

Surface heating is eroding the cap over SE TX and thunderstorms should fire along and ahead of surface low pressure E of I-35 within the next 3-4 hours.

All severe modes are possible.

This will be the begining of the large scale severe weather outbreak tonight.

[vbhoutex]

Looking at radar we have rain beginning to break out to our SW as well as the obvious over the Austin area. Is that the beginnings of the surface low you were mentioning Jeff? It definitely is starting to take on the look of storms coming later just watching the skies outside while raking leaves.

[PurdueWx80]

The surface low is just northeast of Jasper in far eastern TX and the front stretches to the WSW from there down towards Laredo.


The stuff you are mentioning, VB, is mostly elevated in nature. THe highest risk for tornadoes would be along and ahead of the cold front/surface low, while the remainder of precip to the west is still capable of producing very large hail, especially as the upper low nears.

[jeff]

Tornado threat increasing along the central Gulf coast from SC LA to SC AL along and south of northward moving warm front. Surface obs show extremely moist air mass now over SE LA with surface dewpoints in the low to mid 70's and temps. in the upper 70's to near 80. Warm front extends from SE TX to C LA then E through SC MS and SC AL.

Shear profiles will greatly increase over the next several hours as surface low pressure over SE TX intensifies and moves ENE into C LA. Increasing LLJ of 45kts or better and backing surface winds will create a favorable profile for storm rotation. 88D showing scattered to isolated nature of the cells suggest multiple long tracked supercells near and south of northward moving warm front or from NC AL to SC LA.

Additional development is possible over E TX/W LA ahead of surface cold front and surface low combo. Threats will this activity will be mainly large hail and high winds.

A few very large and long tracked tornadoes will be possible this evening from SE LA into C MS and C AL. In addition very large hail and damaging winds will also be possible within the supercell thunderstorms.

Tornado Watch box will likley be issued within the next few hours of the central Gulf coast.

[jeff]

PDS watchbox just issued from SE LA into E AL.

Couple of parameters:

0-1 km shear of 200 m^2/s^2 over SE LA into S MS.

0-3 km of 250-300 m^2/s^2 over the same location.

0-1 km EHI is running around 1-2 over SE LA into S MS

0-3 km EHI is running in the 2-3 range over the same location.

Tornadic supercells will rapidly develop over the next few hours from SE LA into MS and AL. Long tracked damaging tornadoes are expected.

This is a dangerous situation review tornado saftey rules and act quickly if a tornado warning is issued for your area.

NOAA weather radios should be placed into the alert mode and at least some form of public communication should be neraby for your to receive warning information

[jeff]

Supercells continue to rapidly develop within Tornado Watchbox over SE LA into AL.

Strongest cells are over SE LA N of Baton Rough and heading for Mobile AL. Cell heading for extreme NW FL has a well defined hook echo and BWER

Greastest tornado threat continues over SE LA, S MS, S AL, and W FL panhandle.

Some area will be hit multiple times by severe thunderstorms.

Although the shear is favorable and a PDS watch is in effect, few tornado warnings have been issued thus far.

[PurdueWx80]

Yeah, Jeff - in looking at the SPC mesoscale analysis products, it looks like the most favorable storm relative helicity and low-level shear is still just along and south of the shoreline. The richest low-level moisture also appears to be south of a secondary warm-frontal boundary that has only it into southern LA, where dewpoints are now in the low to mid-70's! I would imagine that as the low-level wind field increases in the next few hours, the risk of tornadoes will greatly increase, as the SPC has mentioned in mesoscale discussions and convective outlooks. Tornadoes certainly seem possible with any of the storms currently occurring, but I'm guessing that the most severe, long-tracked tornadoes would have a higher likelihood of occurring as the low-level jet makes it's way inland.

[jeff]

Convection increasing in coverage and intensity across SW into C LA ahead of surface low over extreme SE TX. Little surprised SPC has not hoisted any kind of watch for this area.

Anyhow, supercells will be possible from Lake Charles into C LA west of tornado watch box

However, threat in this area appears to be more of hail and high winds due to limited surface heating although some storm may produce tornadoes.

[PurdueWx80]

Convection increasing in coverage and intensity across SW into C LA ahead of surface low over extreme SE TX. Little surprised SPC has not hoisted any kind of watch for this area.

Anyhow, supercells will be possible from Lake Charles into C LA west of tornado watch box

However, threat in this area appears to be more of hail and high winds due to limited surface heating although some storm may produce tornadoes.

They will be shortly...

http://www.spc.noaa.gov/products/md/md0402.html

[jeff]

Speak of the devil,

NEW PDS watch issued for W LA into NC MS until 1100pm.

Supercells developing ahead of surface low over SE TX will continue to intensify through the evening.

Profiles are favorable for long tracked supercells with all severe modes possible.

Storms will likely begin to congeal into a squall by early evening as the cold front becomes better defined over SW and W LA.

[Yankeegirl]

So I guess thats it for the Houston area? We dodged it again?

[jeff]

Tornado threat continues across extreme E LA, much of MS and SC AL.

Numerous warnings coming out of S and C MS with some pretty good damage reports. Lots of big hail reports.

Supercells with very large hail and tornadoes will continue through the late evening hours over MS into AL and the FL panhandle. Surface low is currently located over WC LA NE of KLCH moving ENE toward WC MS. Cold front is advancing across W LA, however there has been little development due to continued capping and weak low level convergence.

Upper level trough is starting to advance across TX with strong vort crossing SW TX heading for SW LA. Increasing dynamics should help to fire severe convection along the frontal boundary over LA late this evening.

Eastward over MS and AL warm front is lifting northward producing widespread severe thunderstorms from NC FL to SW MS. Tornadic potential is greatest over S and C MS into S and C AL S of newly issued SVR watch. Severe threat will continue to expand northward as warm front moves north bringing very unstable air mass inland. Tornado threat will not be as great over N MS, N AL, and N GA. Additional development late this evening over LA will cross the area overnight with a continued severe threat.

All severe modes remain likely through the overnight including long tracked and violent tornadoes within the PDS boxes.

[Brent]

What's with the big area of rain and embedded storms over Alabama? Normally I would expect this to stabilize us?

[jeff]

Tornadoes on the ground in SC MS.

This is a dangerous situation across MS and AL into NW FL and SE LA tonight.

Short wave and warm front combo responsible for active severe weather across MS and AL into GA and FL is lifting northward. Two powerful supercells producing tornadoes continue along the warm front over C MS south and east of Jackson this evening.

Very juicy air mass is surging northward over all of SE LA, S MS, and S Al south of current convection. Surface low over C LA continues to deepen while tracking ENE toward WC MS. Batch of severe thunderstorms over MS/AL will continue to lift northward along the warm front gradually becoming more elevated the further north you go. Strong large scale ascent over TX will be overspreading the warm and very unstable warm sector over the next 4-6 hours. This should lead to additional severe developments over LA into MS and AL or across areas already hard hit.

MESO note:

Appears a low level outflow boundary has set up from extreme SE LA to off the MS coast to south of Mobile to NW FL where numerous large supercells have tracked today. This boundary is helping to intercept strong Gulf inflow and supercells continue to fire vigorously in this region and move over the same coastal locations. Large hail and tornadoes along with excessive rainfall will be possible in this area.

These storms are moving quickly (35-50mph) so heed warnings and act fast. Tornadoes will continue through the night and this area has had several deadly nocturnal events. Also many locations will be hit more than once, so do no think just because you have had one or two storms that the event is over for your area. You are not in the clear until the surface front passes to your east.

[MSRobi911]

So far Jeff, just some rain and a little wind here...and they are moving fast once they come ashore. Most are missing us and going to AL/FL area and going ashore. Hope no one is on the islands...they have been getting it bad all day from what the radar is showing. If you are out on the island there is no where to go but in your boat and hold on. We have lost people this way, sad to say, some folks don't listen to warnings and still go to the islands to fish and lay in the sun.

Mary