Alert archive / South Carolina / Tornado Warnings in 2020

Tornado Warning 17, NWS Charleston, SC

May 20, 2020Charleston County, South Carolina

NWS Charleston, SC issued this tornado warning at May 20, 2020, 11:47 AM EDT for Charleston County, South Carolina. It was in force for 28 min. 6 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 20, 2020, 11:47 AM EDT (15:47 UTC)
Expired: May 20, 2020, 12:15 PM EDT
In force: 28 min
Issued by: NWS Charleston, SC
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

County Charleston County, SC

The radar

The Charleston,SC radar (KCLX), 92 km from the middle of the area, began a volume at 15:47 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
May 20, 11:47 AM EDT	TORNADO	3 Wsw Johns Island, SC	A NATIONAL WEATHER SERVICE SURVEY TEAM HAS CONFIRMED AN EF-1 TORNADO ALONG AND SOUTH OF CHISOLM ROAD ON JOHNS ISLAND. PLEASE SEE THE PUBLIC INFORMATION STATEMENT (PNS) REGARDING THIS TORNADO FOR ADDITIONAL INFORMATION.
May 20, 11:49 AM EDT	TSTM WND DMG	2 Sw Johns Island, SC	A NATIONAL WEATHER SERVICE STORM SURVEY TEAM DETERMINED THAT STRAIGHT LINE THUNDERSTORM WINDS DAMAGED TREES AT SCATTERED LOCATIONS ALONG MAYBANK HIGHWAY BETWEEN ANGEL OAK ROAD AND OAK GROVE ROAD. TIME WAS ESTIMATED FROM RADAR DATA.
May 20, 11:49 AM EDT	TSTM WND DMG	2 Wsw Johns Island, SC	THE PUBLIC REPORTED DAMAGE TO HOME ALONG CHANEYBRIAR LANE FROM A POSSIBLE TORNADO.
May 20, 11:50 AM EDT	HAIL 1.25	3 Nw Johns Island, SC	HALF DOLLAR SIZE HAIL WAS REPORTED ON JOHNS ISLAND.
May 20, 11:53 AM EDT	TSTM WND DMG	1 Sw Johns Island, SC	AN OFF DUTY NWS EMPLOYEE REPORTED APPROXIMATELY 10 TREES DOWN NEAR THE INTERSECTION OF MAYBANK HIGHWAY AND DOMINIC DRIVE.
May 20, 12:16 PM EDT	HAIL 1	2 S Shadowmoss, SC	QUARTER SIZE HAIL WAS REPORTED IN SHADOWMOSS.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Charleston AFB, SC (KCHS), launched 12:00Z, 3.8 hours before the alert went out and 20 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 631 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 659 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 136 m²/s²
0-3 km storm-relative helicity: 213 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.9

Open this sounding in Storm Lab

The text

As transmitted.

699 
WFUS52 KCHS 201547
TORCHS
SCC019-201615-
/O.NEW.KCHS.TO.W.0017.200520T1547Z-200520T1615Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Charleston SC
1147 AM EDT Wed May 20 2020

The National Weather Service in Charleston has issued a

* Tornado Warning for portions of...
  Charleston County in southeastern South Carolina...

* Until 1215 PM EDT.
    
* At 1147 AM EDT, a severe thunderstorm capable of producing a
  tornado was located over Johns Island, moving northeast at 15 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* Locations impacted include...
  West Ashley, Johns Island, James Island and Maybank Bridge. 

This warning includes I-526 between mile markers 11 and 12.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to an interior room on the lowest floor of a
sturdy building. Avoid windows. If you are outdoors, in a mobile
home, or in a vehicle, move to the closest substantial shelter and
protect yourself from flying debris.

&&

LAT...LON 3265 8010 3267 8015 3284 8011 3280 7998
      3279 7997
TIME...MOT...LOC 1547Z 223DEG 11KT 3271 8010 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

4 follow-up statements

110 
WWUS52 KCHS 201554
SVSCHS

Severe Weather Statement
National Weather Service Charleston SC
1154 AM EDT Wed May 20 2020

SCC019-201615-
/O.CON.KCHS.TO.W.0017.000000T0000Z-200520T1615Z/
Charleston SC-
1154 AM EDT Wed May 20 2020

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1215 PM EDT FOR
CHARLESTON COUNTY...
    
At 1154 AM EDT, a severe thunderstorm capable of producing a tornado
was located over Johns Island, moving northeast at 10 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
West Ashley, Johns Island, James Island and Maybank Bridge. 

This warning includes I-526 between mile markers 11 and 12.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

Report damage directly to the Charleston National Weather Service at
1-888-383-2024 when it is safe to do so.

&&

LAT...LON 3265 8010 3266 8013 3268 8015 3284 8011
      3280 7998 3279 7997
TIME...MOT...LOC 1554Z 216DEG 10KT 3273 8009 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

820 
WWUS52 KCHS 201601
SVSCHS

Severe Weather Statement
National Weather Service Charleston SC
1201 PM EDT Wed May 20 2020

SCC019-201615-
/O.CON.KCHS.TO.W.0017.000000T0000Z-200520T1615Z/
Charleston SC-
1201 PM EDT Wed May 20 2020

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1215 PM EDT FOR
CHARLESTON COUNTY...
    
At 1201 PM EDT, a severe thunderstorm capable of producing a tornado
was located near Johns Island, moving northeast at 15 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
West Ashley, Johns Island, James Island and Maybank Bridge. 

This warning includes I-526 between mile markers 11 and 12.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

Report damage directly to the Charleston National Weather Service at
1-888-383-2024 when it is safe to do so.

&&

LAT...LON 3274 8001 3269 8006 3268 8008 3269 8011
      3271 8013 3284 8011 3280 7998 3279 7997
TIME...MOT...LOC 1601Z 223DEG 11KT 3275 8007 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

227 
WWUS52 KCHS 201607
SVSCHS

Severe Weather Statement
National Weather Service Charleston SC
1207 PM EDT Wed May 20 2020

SCC019-201615-
/O.CON.KCHS.TO.W.0017.000000T0000Z-200520T1615Z/
Charleston SC-
1207 PM EDT Wed May 20 2020

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1215 PM EDT FOR
CHARLESTON COUNTY...
    
At 1206 PM EDT, a severe thunderstorm capable of producing a tornado
was located over Maybank Bridge, moving northeast at 15 mph.

HAZARD...Tornado and half dollar size hail.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
West Ashley, Johns Island, James Island and Maybank Bridge. 

This warning includes I-526 between mile markers 11 and 12.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

Report damage directly to the Charleston National Weather Service at
1-888-383-2024 when it is safe to do so.

&&

LAT...LON 3274 8001 3269 8006 3268 8008 3269 8011
      3271 8013 3284 8011 3280 7998 3279 7997
TIME...MOT...LOC 1606Z 223DEG 11KT 3276 8006 

TORNADO...RADAR INDICATED
HAIL...1.25IN

$$

SPR

332 
WWUS52 KCHS 201614
SVSCHS

Severe Weather Statement
National Weather Service Charleston SC
1214 PM EDT Wed May 20 2020

SCC019-201623-
/O.EXP.KCHS.TO.W.0017.000000T0000Z-200520T1615Z/
Charleston SC-
1214 PM EDT Wed May 20 2020

...THE TORNADO WARNING FOR CHARLESTON COUNTY WILL EXPIRE AT 1215 PM
EDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore the warning will be allowed to expire.  However gusty winds
and heavy rain are still possible with this thunderstorm.

LAT...LON 3274 8001 3269 8006 3268 8008 3269 8011
      3271 8013 3284 8011 3280 7998 3279 7997
TIME...MOT...LOC 1613Z 223DEG 11KT 3277 8005 

$$

The office that day

Everything else NWS Charleston, SC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 19, 9:24 PM EDT	River Flood Warning	CHS	Berkeley, Georgetown, Williamsburg	29 days
May 20, 11:06 AM EDT	Special Weather Statement	CHS	Charleston	39 min
May 20, 11:12 AM EDT	Special Marine Warning	CHS		48 min
May 20, 11:25 AM EDT	Special Weather Statement	CHS	Dorchester	50 min
May 20, 11:34 AM EDT	Areal Flood Advisory	CHS	Charleston	116 min
May 20, 11:40 AM EDT	Severe Thunderstorm Warning	CHS	Charleston	50 min
May 20, 11:58 AM EDT	Special Marine Warning	CHS		92 min
May 20, 12:09 PM EDT	Severe Thunderstorm Warning	CHS	Berkeley, Charleston	66 min
May 20, 12:15 PM EDT	Areal Flood Advisory	CHS	Berkeley, Charleston	90 min
May 20, 12:16 PM EDT	Special Marine Warning	CHS		89 min
May 20, 12:34 PM EDT	Special Weather Statement	CHS	Charleston	41 min
May 20, 1:14 PM EDT	Severe Thunderstorm Warning	CHS	Charleston	61 min
May 20, 1:31 PM EDT	Areal Flood Advisory	CHS	Berkeley, Charleston	89 min
May 20, 1:44 PM EDT	Special Marine Warning	CHS		61 min
May 20, 2:16 PM EDT	Special Weather Statement	CHS	Georgetown	29 min
May 20, 2:23 PM EDT	Areal Flood Advisory	CHS	Charleston	82 min
May 20, 3:40 PM EDT	Small Craft Advisory	CHS		45 hr

Nearby

Tornado Warnings in South Carolina, 2020 Every tornado warning in 2020 Tornadoes in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.