EF1 tornado, Mon Louis to South Orchard, Alabama, September 4, 2011

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mphthis tornado

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF1

Date

September 4, 2011

Touchdown

1:02 AM CDT (06:02 UTC)

Lifted

1:04 AM CDT (06:04 UTC)

On the ground

2 minutes

Path length

1.9 miles (3.1 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

Property damage

$45,000

County

Mobile County

Touchdown point

30.453, -88.110

Lift-off point

30.477, -88.126

Record number

1109040002-01

1 damage points were recorded along this path by NWS MOB, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EFU.

• A small tornado crossed the western-most portion of Dauphin Island. No structures or trees were affected by the brief tornado.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

Tropical Storm Lee began as a tropical wave in the Caribbean Sea during the last week of August. By the evening of Thursday, 1 September 2011, the tropical wave further developed into Tropical Depression 13. By 1 PM the following Friday afternoon, Tropical Depression Lee had formed. Lee slowly moved northward towards the south central Louisiana coastline by Saturday afternoon 3 September, while continuing to produce extremely heavy rainfall over portions of southern Louisiana, southern Mississippi, southern Alabama and the northwest Florida Panhandle. ||The outer rain-bands of Lee produced near-continuous heavy rainfall over portions of southern Alabama, southeastern Mississippi and the northwestern Florida Panhandle by early Saturday morning and that endured through early Sunday before dry air aloft wrapped into Lee���s western side. The center of Lee moved over land around sunrise Sunday, 4 September. However, it would be a while before Lee would weaken to a depression because it remained nearly stationary while the southern half of the circulation was over water where it could continue to derive additional energy from the warm ocean. The next day, Lee was eventually picked up by an upper air trough, turned northeastward and resumed a faster forward speed late in the day on Sunday, 4 September as it began its welcome exit to the northeast late Sunday through late Monday.||Lee���s impacts were far reaching across our region. Although the continuous rains became somewhat intermittent as dry air wrapped into Lee from the west, this created a situation from Sunday afternoon through midday Monday whereby individual thunderstorms became more intense due to increasing levels of atmospheric instability. Stronger thunderstorms and isolated tornadoes affected the North Central Gulf Coast Region, as they formed within the detached outer spiral rain-bands well to the east of Lee���s center on Sunday and finally to the southeast on Monday. The highest total storm tide levels (astronomical plus surge effects) ranged from approximately 3.5 to just barely over 5 feet.||While Lee was in the process of being picked up by a fast moving upper air trough, a series of squall lines that produced moderately widespread thunderstorm wind damage along and ahead of the surface cold front, as well as more isolated tornadoes, affected the area through late Monday afternoon. In all, some 10 to 15 inches of rain fell along coastal sections of Alabama and northwest Florida. Additionally, several weak tornadoes occurred producing modest structural and tree damage. There was also moderate beach erosion and the rip currents endured over a multi-day period. Inland flooding was exacerbated along the immediate coastal zone by higher tide levels due to Lee���s surge effects which created poor to no drainage of area coastal rivers, bays and sounds on during astronomical high tide cycles from 3-5 September (late night hours each day).

A tornado moved onshore near the mouth of East Fowl River on Byrnewood road and tracked northwest to the end of Pioneer Road in the Bellefontaine community. The tornado produced extensive damage to trees consistent with EF-1 type damage and winds between 86 MPH and 110 MPH. Four residences and one large barn had structural damage in the area between Bay Road and Pioneer Road. Of those structures, one mobile home was almost completely destroyed from a large tree that fell on it, with minor damage to mostly roofing shingles and window panes observed with the other three homes. The barn received minor structural damage on an exterior wall with three large roll-up doors completely blown out.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

3 minutes of warning. NWS MOB issued a tornado warning for this county at 05:59 UTC, 3 minutes before the tornado touched down, in force until 07:00 UTC.

The county was under a tornado watch, issued at 02:48 UTC and running to 10:05 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 05:54 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Mobile Downtown (BFM), 19 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Mobile radar (KMOB), 27 km away, was scanning. The volume nearest the touchdown began at 06:02 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2011 tornado in AlabamaEvery tornado in Alabama since 1950Warnings in force in Alabama nowThe forecast where you are

13 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.