A boundary across the area triggered isolated severe thunderstorms during the afternoon hours. Storm reports were mainly large hail.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MRX wrote it up.
A boundary across the area triggered isolated severe thunderstorms during the afternoon hours. Storm reports were mainly large hail.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Morristown, TN wrote its last area forecast discussion before the first event at Apr 20, 2:45 AM EST, 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 345 AM EDT WED APR 20 2011 .SHORT TERM...(TODAY THROUGH TONIGHT)...BOWING LINE OF SHOWERS AND THUNDERSTORMS WITH A HISTORY OF DAMAGING WIND GUSTS APPROACHING PLATEAU COUNTIES AT THIS TIME AND STILL LOOKS TO PRODUCE POTENTIAL FOR DAMAGING WINDS ACROSS WESTERN SECTIONS OF FORECAST AREA NEXT FEW HOURS. LINE SHOULD REACH PLATEAU IN THE NEXT HOUR AND REACH THE WESTERN VALLEY AREAS BY AROUND 10Z. TEMPERATURES ARE VERY MILD IN THE 60S AND LOWER 70S ACROSS THE FORECAST AREA EXCEPT 50S IN SHELTERED VALLEYS OF THE NE. DEW POINTS ARE AROUND 60 PLATEAU BUT 40S TO MID 50S ELSEWHERE. LINE EXPECTED TO WEAKEN CONSIDERABLY BY SUNRISE THIS MORNING AS IT MOVES INTO DRIER AIR MASS. SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE AHEAD OF COLD FRONT NOW NEAR MS AND LOWER OH RIVERS. THE FRONT SHOULD SLOWLY MOVE EAST AND REACH NEAR THE MOUNTAINS AND SOUTHERN TN BORDER BY ABOUT 00Z TONIGHT. IT WILL BECOME NEARLY STATIONARY JUST SOUTH OF THE BORDER OVERNIGHT. HAVE RAIN CHANCES HIGHEST IN THE MORNING AS SHOWER AND THUNDERSTORM MASS DIES OUT ACROSS FORECAST AREA. AS CLOUDS BREAK UP THIS AFTERNOON. SCATTERED CONVECTION SHOULD BREAK OUT AGAIN ESPECIALLY SOUTH AND EAST WHERE INSTABILITY WILL BE HIGHER AND AIR LESS WORKED OVER FROM MORNING CONVECTION. HIGH TEMPERATURES NEAR 80 TODAY AND COOLER TONIGHT WITH SLIGHTLY DRIER AIR MASS BEHIND FRONT. WILL KEEP SHOWERS AND THUNDERSTORMS AROUND IN THE EVENING ALL AREAS ENDING NORTH AND A CHANCE SOUTH WITH FRONT NEARBY. .LONG TERM...(THURSDAY THROUGH TUESDAY)...UPPER RIDGE STAYS SE OF AREA THROUGH PERIOD. MODERATE UPPER FLOW ACROSS TN VLY WITH MAIN JET ACROSS OH VLY THROUGH SUNDAY. BROAD TROUGHING SETS UP ALOFT WEST OF AREA EARLY NEXT WEEK AS UPPER FLOW BECOME MORE SWRLY ACROSS E TN VLY AND S APPALACHIANS. SURFACE WARM FRONT RETURNS NORTH THROUGH THE AREA THU AND THU NGT. FOCUS OF CONVECTION WILL TAG ALONG THIS BOUNDARY. POPS MAY BE UNDERDONE WITH CONVECTIVE CHANCE PRETTY GOOD WITH PWATS INCREASE TO >1.00. CONVECTION CHANCE REMAINS HIGH ALONG TN/KY/VA BORDER FRIDAY BUT DECREASES THROUGH THE WEEKEND AS WARM FRONT MOVES NORTH. DIURNAL TSTMS POSSIBLE EARLY NEXT WEEK. TIMING OF MID WEEK FAIRLY STRONG COLD FRONT UNCERTAIN AT THIS TIME. WENT ABOVE CLIMO AND A BIT WARMER THAN MOS GUIDANCE THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 80 57 77 60 80 / 70 40 50 40 40 KNOXVILLE MCGHEE TYSON AIRPORT, TN 79 55 74 56 79 / 70 30 50 40 50 OAK RIDGE, TN 78 54 72 55 79 / 70 30 30 40 50 TRI CITIES AIRPORT, TN 79 49 70 49 73 / 70 20 20 30 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && TD/SON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MORRISTOWN TN 401 AM EDT WED APR 20 2011 NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002- 005-006-008-210815- CHEROKEE-CLAY-SCOTT TN-CAMPBELL-CLAIBORNE-HANCOCK-HAWKINS- SULLIVAN-JOHNSON-MORGAN-ANDERSON-UNION-GRAINGER-HAMBLEN- NORTHWEST COCKE-COCKE SMOKY MOUNTAINS-NORTHWEST GREENE- SOUTHEAST GREENE-WASHINGTON TN-UNICOI-NORTHWEST CARTER- SOUTHEAST CARTER-ROANE-LOUDON-KNOX-JEFFERSON-NW BLOUNT- BLOUNT SMOKY MOUNTAINS-NORTH SEVIER-SEVIER SMOKY MOUNTAINS- SEQUATCHIE-BLEDSOE-RHEA-MEIGS-MCMINN-NORTHWEST MONROE- SOUTHEAST MONROE-MARION-HAMILTON-BRADLEY-WEST POLK-EAST POLK-LEE- WISE-SCOTT-RUSSELL-WASHINGTON- 401 AM EDT WED APR 20 2011 /301 AM CDT WED APR 20 2011/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST NORTH CAROLINA...EAST TENNESSEE AND SOUTHWEST VIRGINIA. .DAY ONE...TODAY AND TONIGHT A WEAKENING SQUALL LINE OF STRONG THUNDERSTORMS IS EXPECTED TO MOVE ONTO THE CUMBERLAND PLATEAU DURING THE EARLY MORNING HOURS. A FEW THUNDERSTORMS MAY BE SEVERE...WITH DAMAGING WINDS...AND LARGE HAIL...BEFORE SUNRISE. THUNDERSTORMS...SOME POSSIBLY SEVERE...WILL CONTINUE OVER THE REGION THIS MORNING...WITH ADDITIONAL REDEVELOPMENT EXPECTED DURING THE AFTERNOON AS A COLD FRONT MOVES THROUGH THE AREA. A FEW STORMS MAY BECOME SEVERE WITH DAMAGING WINDS...LARGE HAIL...AND LOCALLY HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY A WARM FRONT WILL MOVE NORTH THURSDAY INTO FRIDAY WITH THE BOUNDARY NEAR THE TENNESSEE AND KENTUCKY BORDER AREA FRIDAY. THUNDERSTORMS ARE EXPECTED TO FORM ALONG THIS BOUNDARY. A FEW STORMS MAY BECOME SEVERE WITH DAMAGING WINDS...LARGE HAIL...AND LOCALLY HEAVY RAINFALL. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS MORNING AND LATER TODAY AS WELL AS FRIDAY. TD/SON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE MORRISTOWN TN 353 AM EDT WED APR 20 2011 TNZ012-013-035-036-200845- ANDERSON TN-CAMPBELL TN-MORGAN TN-SCOTT TN- 353 AM EDT WED APR 20 2011 ...SIGNIFICANT WEATHER ADVISORY FOR MORGAN...CAMPBELL...ANDERSON AND SCOTT COUNTIES UNTIL 445 AM EDT... AT 348 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 10 MILES NORTHEAST OF JAMESTOWN TO 7 MILES SOUTHEAST OF SPARTA...AND MOVING NORTHEAST AT 55 MPH. SMALL HAIL AND WIND GUSTS UP TO 45 MPH ARE EXPECTED WITH THESE STORMS. LOCATIONS NEAR THE PATH OF THESE STORMS INCLUDE...ONEIDA... WARTBURG...LA FOLLETTE...HUNTSVILLE...JACKSBORO...BIG SOUTH FORK NATIONAL REFUGE...RUGBY...WINFIELD...HIGH POINT...DEERLODGE...PINE ORCHARD...ELGIN...SUNBRIGHT...OAKDALE...KETCHEN...PETROS...SLICK ROCK...ROSEDALE...SMOKEY JUNCTION AND NORMA. 17
The Knoxville radar (KMRX), 107 km away, was scanning. The volume nearest the first event began at 08:20 UTC.
1 hail. Local standard time, as filed.
The Oneida Police Deported reported dime to quarter-size hail fell for a few minutes by a thunderstorm in Oneida.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Tennessee in 2011Every state in 2011This day in weather historyWarnings in Tennessee, April 2011
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 292195.