Fairfield Tornado an EF-1

While Tropical Storm Cindy was coming ashore near the Louisiana-Texas line between Port Arthur, TX, and Lake Charles, LA, Alabama was taking a lashing. This is not a terribly rare occurrence and brings to mind tornado damage from Hurricane Allen when it was in the southern Gulf of Mexico. NWS Acting Meteorologist-in-Charge Kevin Laws did a preliminary survey during the afternoon of Thursday, June 22nd, and initially rated the damage EF-2.

Earlier today, the NWS was able to do additional surveying of the damage and found evidence to suggest the damage was more consistent with the upper end of the EF-1 category. Here is the full story of the rating change and reasoning as published by the NWS.

-Brian-

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Public Information Statement
National Weather Service Birmingham AL
314 PM CDT Sat Jun 24 2017

..PUBLIC INFORMATION STATEMENT...

..UPDATED NWS DAMAGE SURVEY STATEMENT FOR JUNE 22ND, 2017 TORNADO
IN WESTERN JEFFERSON COUNTY AND WESTERN SHELBY COUNTY TORNADO DEBRIS
SIGNATURE...

LATEST INFORMATION...

Thunderstorms on Friday prevented the survey team from
fully assessing the damage track of the Jefferson County tornado.
This assessment was completed today, Saturday June 24th. The team
surveyed from Bessemer to either side of Interstate 459 and found a
few trees uprooted over an 8-mile span leading up to the steadier
swath of damage from Brighton and points northeast (surveyed Friday
June 23rd). Given irregular and gap-filled damage points, those
located south of Brighton are not included in the track; thus, the
location of tornado touchdown is maintained at Brighton. Details on
the track and associated damage are outlined below.

Also, here's some information regarding damage to the KFC, Express
Oil Change, ABC Store, and adjacent mini strip mall, and the decision
to downgrade from EF-2 to EF-1: Damage to the KFC included broken
windows and one point of exterior wall damage, possibly the result
of debris shedding and impact from an adjacent building. The extent
of damage to the KFC is in line with EF-0 caliber damage. The
Express Oil Change had an uplift and shifting of the entire roof,
which then resulted in the failure of several walls. Three large car
bay doors, and three additional bay doors in an adjoining work area,
likely served as the entry point for tornadic winds to lift the roof
and result in further damage to the structure. The extent and manner
of damage to the Express Oil Change suggests EF-1 caliber damage.
The ABC Store had complete structure failure, aside from a few
interior walls, due to the type of building framing, as well as the
method of wall-to-foundation fastening. Despite the dramatic
appearance of near-complete destruction, all things considered point
toward EF-1 caliber damage. EF-1 level damage was also evident
extending northward to the mini strip mall and the first few units of
the Fairfield Housing Complex. A careful re-assessment of damage
indicators (affected buildings), degree of damage (extent of damage
to buildings, plus consideration of construction quality and windy
entry points), and surrounding signals led to a rating for this
tornado at high-end EF-1 intensity.

The survey team also inspected an area of western Shelby County for
tornado damage, but could not find any despite a debris signature on
radar. Details are outlined below.

OVERVIEW...

Bands of showers and a few thunderstorms, rotating around the
remnants of Tropical Storm Cindy, produced flooding rainfall and
tornadic activity. One storm produced a tornado of EF-1 intensity in
western Jefferson County. A second storm produced a tornado debris
signature in western Shelby County.

Tornado #1 Fairfield Tornado (Jefferson County)...

Rating: EF-1
Estimated Peak Wind: 110 MPH
Path Length: 8.29 miles
Path Width: 255 yards
Fatalities: None.
Injuries: 3.

Start Date:June 22 2017
Start Time: 12:21 CDT
Start Location: 4 NNE Bessemer
Start Lat/Lon: 33.4282/-86.9397

End Date:June 22 2017
End Time:12:38 CDT
End Location:4 W Birmingham
End Lat/Lon:33.5317/-86.8670

Survey Summary: National Service Meteorologists surveyed storm damage
in western Jefferson County, and found that the damage was
consistent with a tornado. There were three separate notable
increases in damage severity and/or density, likely indicating that
the tornadoe's funnel had a skipping/cycling characteristic as it
swayed from less to more intense.

The tornado touched down along 5th Street North, between Highway 11
and Avenue A, where damage ranged from broken large limbs to uprooted
and snapped trees. The tornado then traveled northeast with a long
swath of damage centered along a track generally between Interstate
20/59 and Highway 11. Aside from continued uprooting of trees and
downing of limbs, the first notable damage occurred just west of
Western Hills Mall, where there was hefty damage to an Express Oil
Change, Alabama ABC store, and mini strip mall, along Dr. M.L.K.
Boulevard. Damage at this location was likely the result of a short-lived,
concentrated vortex, with a track around 300 yards in length and EF-1
intensity. Beyond this point, damage fell into EF-0.

The tornado continued knocking down trees as it moved northeast,
with some trees falling onto homes, resulting in severe roof damage.
Tornadic winds also caused minor to moderate roof damage ranging
from missing shingles to sections of roof damaged or blown off,
especially in neighborhoods adjacent to Miles College (to the south
and northeast). Given a noticeable increase in damage density, it's
possible that the tornado briefly intensified in this area, over the
course of roughly a 700 yard path. While there was an obvious
increase in the amount of uprooted trees, there was a large
contribution from shallow root systems and especially saturated soil
from several-day's rain; thus, given a lack of notable wind-driven
damage to homes (which held in EF-0, characteristic of shingle and
roof trim damage), the overall damage pattern didn't tip the scale
for a small corridor of EF-1 rating.

Next, the tornado neared and crossed Interstate 20/59 where the extent
of damage backed off, though some minor structural damage done to
the Tire Tech car bay, and Freeway Honda. Windows were also blown out
of a few cars at Honda dealership. An increase in the number of
uprooted trees was again observed surrounding Tuxedo Park on the
north side of Interstate 20/59, along with roof damage to a few
homes. Tornado damage became very sporadic and increasingly less
significant as the tornado neared Bankhead Highway, dissipating near
the CSX Transportation railways adjacent to Pratt Highway.

Western Shelby County Tornado Debris Signature...

Doppler radar showed a velocity couplet and debris signature,
indicating a tornadic circulation producing damage, at 2:42 PM along
County Road 10, northeast of Marvel. This circulation then quickly
weakened as it moved northeast. The survey team was unable to locate damage
due to: 1) hindrance from dense forest, inaccessibility, and
terrain; and/or 2) the tornado only lofted small vegetative debris.

$$

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Category: Alabama's Weather, ALL POSTS, Severe Weather