3/3/08 FCST: LA/MS/AL/GA/TN/KY/FL

[Jim Leonard]

Looking at the 18Z gfs I would think the best area for significant severe weather would be in areas of southern Mississippi, Alabama, Florida panhandle ito Georgia overnight Monday into Tuesday. The upper dynamics, according the latest data really intensifies during this period. One would expect upper 60 dewpoints to be streaming just ahead of this system along the NE Gulf coast.

 

[Chad Cowan]

Monday could be the biggest day of the three in terms of areal coverage and the potential for sig tors. A large squall line will likely be ongoing Monday morning west of the MS river along the CF and will spread east and strengthen throughout the day. Widespread damaging wind gusts will be likely, but the potential also exists for embedded supercell characteristics and LEWP's within this squall due to the massive amount of LL shear associated with the deepening sfc low. The highest tornado potential will be within any discrete storms that will develop along the WF into TN and KY and S along the gulf coast where deeper moisture will be in place. The svr threat will continue overnight and spread NE.

 

[Brett Adair]

Current data looks underdone on dewpoints and associated instability values especially across MS/AL. WRF-NMM currently looks good with little in the way of capping breaking shortly after 18z across MS/W AL with supercells developing south of MEI and then developing further eastward from that point on. MOS temperature profiles are likely underdone again as they were by some 6 degrees today on high temperatures across my region. I do think this has high risk potential with the very strong mid/upper level dynamics and a deepening surface low available to pump up the moisture. Ageostrophic winds suggest very rapid development with the ejection of the surface cyclone. As the very strong low level jet moves over MS/AL/TN and increases, activity will likely become very robust and significant with long track, damaging tornadoes becoming a possibility within and ahead of the main convective line. This looks very serious.

 

[Brian Stertz]

The 00z ETA was showing incredible 0-1km shear (30-40 kts.) and adequate instability (1200-1600 j/kg SB CAPEs) for tornadic supercells Monday afternoon/evening. over SE/EC Arkansas into adjacent areas of NE Louisiana, NW/WC Mississippi, and possibly far SW Tennessee. The 0-1km forecasted shear vectors are strongly backed and this coupled with very diffluent and strong southwesterly flow...could really spell some trouble for the Delta region. The big key is if any rogue low topped supercells can get going ahead of the broken line by afternoon. If this happens, there could be some long tracked strong/damaging tornadoes. Still feel strong tornadoes will be possible within the broken line though. The shear is just plain nasty Monday...looks certainly worthy of a MDT risk at this juncture. I'll post my updated threat map on Vortex Times in a few mins.

 

[Bill Schintler]

Chase Target for Monday, March 3

Chase target:
Lewisville, AR (25 miles east of Texarkana)

Timing and storm mode:
Ongoing convection will move into the target area through 2 PM CDT. A full spectrum of severe weather will be likely, including a few tornadoes. Chasing conditions will be poor due to a combination of rapid storm motion to the northeast at over 40mph, a poor road network in southwestern AR, and thick low- and mid-cloudiness that will result in poor visibility of storm features.

Synopsis:
SWRN CONUS ULVL trough will slide E during the period in response to attendant 100kt H5 streak rounding the trough base. In response, H5 height falls will spread over much of AR and LA during the day Monday. This evening, line of post-frontal convection was underway in CNTRL OK, with instability based on parcels originating at between 1000-1500m AGL. Further E, additional convection was firing in the exit region of 60kt H3 flow.

Discussion:
Convection will be ongoing during the morning hours in much of ERN OK through NERN TX. To the E of this convective area in AR and LA early in the period, thick low- and mid-level cloudiness will limit insolation. A short window of opportunity for discrete storm structure should nevertheless exist during the early afternoon immediately NE of a wave along the CF. In this area, winds should back slightly, and a few SFC-based discrete cells are likely E of the ongoing elevated convection. This is also the WRN fringe of the strongest H85 flow, to the W of which the speed of the 60kt SWRLY LLJ falls off rapidly along with the magnitude of helicity. By mid-afternoon, widespread convection should explode over much of AR and AL, limiting potential for further discrete convection.

Modest SFC-based instability will coexist with very impressive shear parameters. Large hodograph curvatures in the SFC-3km layer with SRH’s in excess of 500m2/s2 along with LCL’s in the 500m AGL range will greatly enhance tornado threat.

- bill
8:45 PM CST, 03/02/08

 

[Darrin Rasberry]

This setup's details feel much like the South Texas setup last month, including the hopeful possibility that squall soup will swallow all the cells before they rage more damage on the battered area. Should the speed be slowed a bit, though, I wouldn't be surprised to see a noon bump to HIGH for the LA/MS coastal region if the system doesn't drag the cloud cover it had today down there.

 

[Terry Tyler]

This looks very serious.

i agree with you, brett...im really liking the looks of this one...

not too much cloud cover, decent dewpoints and instability profiles with a powerful jet its all there...ill tell you this, the surface winds are really going right now...

very exited about this, im staying here in auburn until something develops, then ill probably go out and see whats up...