3/26/05 NOW: TX, LA, AR, MS, AL, FL, AL, GA

OK, a moderate risk is in effect for much of this area and a brand new PDS tornado watch has just been issued for SRN AL, MS as well as parts of LA and the FL Panhandle.

A few storms are developing in the vicinity of the watch. KEOX (Ft. Rucker, AL) radar showing a well developed, very isolated cell now in the Pike and Barbour County areas. Severe thunderstorm warnings are in effect. Radar is indicating it may be producing hail as large as 2.25" at this time. I see nothing to indicate it has any tornadic potential at this time. But it's definately a severe storm.

-George
 
Many severe storms are forming across the area, but I am unimpressed with the surface winds.



http://www.rap.ucar.edu/weather/surface/di...on=lit&nplots=1

The best I could find is 15 knots from the SE (MCB). The winds don't increase until later this evening. Looking at the RUC for 0900 Sun (initialized 21 Z Mar 26), the best winds are in southern Alabama and they still are not that high.

http://www.rap.ucar.edu/weather/model/ruc1...hr_sfc_mslp.gif

I am less impressed with this event. If there are tornadoes, most won't occur until after dark. Certainly a dangerous situation for the residents of those areas. Even strong straight line winds can turn over a mobile home.

Bill Hark
 
I'm not concerned with the surface winds, since the lower the surface winds, the longer the hodograph (in this case) and the higher the helicity (assuuming our low-level winds increase with height, which they aren't much right now). If there's anything to be concerned with, it seems to be the above-surface winds near 850mb, which are pretty weak, though are gradually strengthening. Per SPC mesoanalysis, LCLs are very low across the two PDS watch box areas, and instability and low-level flow (shear) is gradually increasing as well. I've just wondering if the southern MS area will become too worked over later this evening from the current, widespread severe (yet non-tornadic) storms occurring. Siggy Torn. parameter is edging up with time, so I think there is a significant threat of strong tornadoes in the area.
 
First tornado warning of the day now in Mississippi. As of 5:42 PM EST, the area of rotation was in NERN Lincoln County and getting ready to cross into NW Lawrence County.
 
To a quickie post..

For those following this... You can see the new polygon warnings in action from Jackson NWSFO at http://www.srh.noaa.gov/jan/warning_map.html

First tornado warning of the event so far just issued for southern MS storm. Nice storm moving just east of New Orleans as well. Interesting that there's some clearing occurring between this storm and the cell to the north. It appears that the clearing will allow for a little more insolation (until the sun sets soon) and provide a little more potential to build up some instability...
 
First tornado warning of the day now in Mississippi. As of 5:42 PM EST, the area of rotation was in NERN Lincoln County and getting ready to cross into NW Lawrence County.

Just sitting here comparing the wxworx display with the COD site radar products... That storm has had consistent shear markers on it for the better part of an hour now. It's currently indicating a 92mph shear marker to the WNW of Prentice, MS (SE of Jackson) which is the highest one I have seen so far. Area of rotation is indidated to have shrunk from about 10 miles width to now 4 miles width. Be interesting to see if this produces.
 
Radar isn't too impressive at this time, with a couple of supercells in the watch boxes... Most of the activity appears to be on the downswing as showers/storms continue to develop in a rather widespread nature across much of MS and AL. There were a couple of impressive supercells with nice meso earlier this evening that cross the LA/MS border, though those have largely either become linear in reflectivity appearance, or dissipated. Additionally, there was a nice supercell tracking just off the MS/AL coast, though that too weakened rather rapidly.

The latest SPC mesoanalysis continues to show marginal surface-based instability across the region, with CAPEs largely <500. There is an area of better SBCAPE (1000-1500) in southern LA, though nothing has been able to fire in that area. Otherwise, the best low-level shear remains in MS, where instability is marginal at best (<500 CAPE) courtesy of a rain-cooled boundary layer from the numerous/widespread thunderstorms late this afternoon. These storms have also temporarily 'worked-over' the atmosphere, resulting in poor lapse rates. Of course, with strong mid-level flow, this airmass will quickly advect downstream, being replaced by steep lapse rates to the west and southwest. I don't expect much to happen until the surface low moves farther to the east/northeast and pulls some of the better low-level moisture northward into MS and AL. Low-level shear is strengthening in MS/AL, though that's courtesy of the backed, yet very stable, flow. Some of the stable near-surface air will likely begin to mix a bit as stronger low-level (850mb) winds move into the area, though that'll veer the winds a bit as well. Deep layer shear certainly remains impressive (60-75kts) across the risk area, so surface-based supercells are likely if enough instability is present.

It was interesting to see that left-split / anticyclonic supercell haul northward across Jackson an hour or so ago. An impressive, relatively long-lived anticyclonic supercell...
 
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