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Winter Storm Shifting From the Central U.S. to the Northeast; Severe Thunderstorms in the South

A winter storm will track to the Lower Mississippi River Valley by Monday and across the central Appalachians Monday night to southern New England by Tuesday. A swath of snow, sleet and freezing rain will spread from the Central Plains east into southern New England by Monday and Tuesday. Severe thunderstorms with damaging winds and tornadoes are possible over the northern Gulf Coast on Monday. Read More >

On the evening of March 9th, 2017, a strong cold front was pushing southeast from southern Missouri/Kentucky extending northeast into the Mid-Atlantic area of the U.S.  Fairly strong low and mid-level winds (850 mb winds ~40 knots/500 mb winds of 60-70 knots) were in place ahead of the cold front. Ahead of the front (over the Huntsville Forecast area and further northwest), several other severe weather ingredients were in place. These ingredients came together ahead of the front to produce a Mesoscale Convective System (MCS) comprised of strong to severe thunderstorms. They included: surface based instability values of up to 500 J/KG, steep mid-level lapse rates between 700 mb and 500 mb of ~ 7 degrees Celsius/km, and 0-1 km helicity (low level turning of winds) values of 200-400 m2/s2. This MCS raced southeast through northern Alabama and Southern Middle Tennessee around midnight through ~ 3 AM. This activity weakened towards daybreak as the front pushed southeast into central Alabama.

As seen below on the left, a severe thunderstorm watch was issued at 11:20 PM for all of the counties in NWS Huntsville's forecast area. This was in effect until 4:00 am. On the right is a map of storm reports received after these storms pushed through the area. The most widespread effect of this MCS was damaging winds, but enough low-level helicity was in place ahead of the front to produce an isolated EF-1 tornado that affected Moore and Franklin counties in Tennessee. A few instances of large hail were observed as well given the strong forcing with the front and steep mid-level lapse rates.

Storm Reports
Severe Thunderstorms Watch #75 was issued at 11:20 PM. Click to image to view the storm reports.


Moore and Franklin counties TN

Date March 9, 2017
Time (Local) 11:55 PM CST
EF Rating EF-1
Est. Peak Winds 100 mph
Path Length 5.18 miles
Max Width 320 yards
Injuries/Deaths 0


 An EF-1 tornado touched down in approx. 5 
 miles ENE of Lynchburg, TN.  The tornado 
 continued  in a generally ESE direction 
 across into Franklin  County before gusting 
 out approx. 4 miles W of Estill Springs, TN.

Click here for more details.

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Upper Air Charts

250mb Chart at 6pm March 9th

500mb Chart at 6pm March 9th

850mb Chart at 6pm March 9th

250mb Chart at 6am March 10th

500mb Chart at 6am March 10th

850mb Chart at 6am March 10th

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Surface/Mesoscale Anaylsis

9pm March 9th

Midnight March 9th

3 am on March 10th

0-1 km Helicity at 11 PM on March 9th, 2017. Mid-Level Lapse Rates (700-500 mb) at midnight on March 9th, 2017.
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SPC Outlooks

Day 1 Outlook 
Issued 7 am March 9th


Day 1 Outlook 
Issued 10:30 am March 9th

Day 1 Outlook
Issued 2 pm March 9th

Day 1 Tornado Probability
Issued 2 pm March 9th

Day 1 Wind Probability
Issued 2 pm March 9th

Day 1 Hail Probability
Issued 2 pm March 9th

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KOHX radar at 1150 PM; approximately 5 minutes before the tornado touched down. KOHX radar at 1156 PM; approximately 1 minute after the tornado touched down.
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Event Images

This mobile home was destroyed on Riddle Lane. (NWS Storm Survey - Tornado Damage)

One tree in this photo was snapped near its based and other tree damage is noted on Gourdneck Road. (NWS Storm Survey - Tornado Damage)

Some damage was seen to this barn on Gourdneck Road. (NWS Storm Survey - Tornado Damage)

Trees were uprooted and blown down in this area on Turkey Street Loop Road. (NWS Storm Survey - Tornado Damage)

Trees were snapped and blown down in the same direction in this area along Tankersley Road. (NWS Storm Survey - Straight Line Wind Damage)