Friday, May 6, 2011

Second Mississippi April 27 Tornado Upgraded to EF-5

Images (click to enlarge): Preliminary April 25-28 tornado tracks as of May 6, pavement and turf gouging from the Neshoba County, Mississippi EF-5 tornado, from NWS

As the painstaking work of surveying the damage from the record tornado outbreak continues, the National Weather Service (NWS) announced this afternoon that a second Mississippi tornado on April 27 has been upgraded to EF-5 intensity. The new evaluation of the Neshoba/Noxubee County storm was based on analysis of extraordinary ground damage consistent with EF-5 strength winds: Large sections of sod and asphalt paving were literally ripped out of the ground.

This was the first EF-5 tornado in the area covered by the Jackson, Mississippi NWS office in over 40 years, since Feb. 21, 1971. Along with the previously identified Smithville EF-5, this was the first time since tornado records began that 2 EF-5 tornadoes have been observed in Mississippi on the same day. This also brings to 3 the number of EF-5 storms in the record outbreak of April 25-28, with about two-thirds of the storms surveyed so far.

The total number of confirmed tornadoes in the Jackson region now stands at 31, with
 4 EF-0
10 EF-1
11 EF-2
4 EF-3
1 EF-4
1 EF-5
The NWS reports:
IN TWO LOCATIONS...THE TORNADO ACTUALLY GOUGED OUT LARGE SECTIONS OF
THE GROUND. IN ONE SPOT IN NORTHEAST NESHOBA COUNTY...THE GROUND WAS
DUG OUT TO A DEPTH OF AROUND 2 FEET OVER AN AREA APPROXIMATELY 25-50
YARDS WIDE AND A COUPLE OF HUNDRED YARDS LONG. SIMILAR GOUGES...
ALTHOUGH NOT AS LONG OR DEEP...WERE ALSO OBSERVED IN EXTREME
NORTHWEST KEMPER COUNTY. WHILE THE EXACT MECHANISM THAT CAUSED THIS
DAMAGE IS UNCLEAR...INDICATIONS ARE THAT THIS TYPE OF GROUND DAMAGE
IS TYPICALLY ASSOCIATED WITH THE EXTREME WIND SPEEDS ASSOCIATED WITH
EF-5 TORNADOES.

IN THE AREA OF NORTHWEST KEMPER COUNTY WHERE THE GROUND GOUGING WAS
OBSERVED...THERE WAS ALSO AN AREA WHERE PAVEMENT WAS REMOVED FROM
THE GROUND. WHILE THIS TYPE OF DAMAGE CAN BE CAUSED BY TORNADOES OF
LESS THAN EF-5 INTENSITY...THE FACT THAT PIECES OF ASPHALT WERE
FOUND AT A SIGNIFICANT DISTANCE AWAY...BOTH UPWIND AND DOWNWIND OF
THE ROAD...ARGUES FOR EXTREME WIND SPEEDS. SIMILAR TYPE DAMAGE WAS
ALSO OBSERVED IN SOUTHWEST NOXUBEE COUNTY.

FINALLY...EXTREME VEHICLE DAMAGE OF THE TYPE NORMALLY ASSOCIATED
WITH EF-5 TORNADOES WAS OBSERVED. THIS INCLUDED NEW VEHICLES BEING
MOVED MORE THAN 100 YARDS FROM WHERE THEY STARTED...AND BEING LEFT
IN A NEARLY UNRECOGNIZABLE STATE.

Seasonal Outlook

Latest seasonal forecast: Click here.


Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.