EF0 tornado, Moca, Puerto Rico, August 7, 2011

1. EF065 to 85 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF0

Date

August 7, 2011

Touchdown

12:35 PM CDT (17:35 UTC)

Lifted

12:42 PM CDT (17:42 UTC)

On the ground

7 minutes

Path length

0.8 miles (1.3 km)

Path width

80 yards (73 m)

Deaths

0

Injuries

0

Property damage

$80,000

County

Not recorded

Touchdown point

18.379, -67.096

Lift-off point

18.374, -67.082

Record number

1108071135-01

The National Weather Service conducted a storm damage survey that occurred from route PR-125 to the southwest town of Moca through Barrio Cruz to route PR-111 on the east side of town. After a damage survey and eyewitness accounts, the National Weather Service determined that a tornado estimated at EF-0 on the enhanced Fujita scale affected the Cuba sector and Barrio Cruz neighborhood during the early afternoon hours of Sunday August 7th with estimated winds of 65 to 75 mph. ||The tornado formed within a cluster of severe thunderstorms that developed across the interior mountain range near Adjuntas municipality and moved rapidly northwest northwest around 20 mph through the municipalities of Lares, San Sebastian, and Moca. The small circulation of the tornado was likely caused by a small low pressure area or meso low that typically develops during the afternoons over northwest Puerto Rico during the summer months due to interaction of the west coast sea breeze and the prevailing trade winds. Depending on the magnitude of the prevailing and local winds, this meso low can create sufficient horizontal spin in the atmosphere to create small rotating columns of air to generate a tornado assuming enough moisture and instability are present. In other words...this tornado was generated|by boundary interactions and not from a typical tornadic supercell. The path of wind damage started from near PR-125 to the southwest of town and then continued for approximately 0.8 miles to the northwest through some open field and through the streets of Los Cipreses and Los Loperena where it crossed PR-125 again to near|PR-111 where the tornado was seen to have lifted up or dissipated.||The damage from the ef-0 tornado consisted of many trees snapped with a couple of them uprooted...an overturned truck parked on the street Los Cipreses, broken glass and windows to some residences and a power pole snapped. Evidence of the tornado included a video which showed a funnel cloud touching the ground with debris blowing in different directions, trees falling in a convergent pattern...eyewitness reports and leaves splattered on all four sides of structures.||The large amount of trees snapped suggests that winds within the tornado reached 65 mph while a couple of large uprooted trees indicate winds may have reached up to 75 mph. It is estimated that this tornado traveled a distance of up to 0.8 miles and lasted between 5 and 10 minutes.||The National Weather Service in San Juan issued a severe thunderstorm warning for the municipalities of San Sebastian, Moca, Aguada, Aguadilla and Isabela. A special weather statement was also issued prior to the severe thunderstorm warning highlighting the threat of strong thunderstorms with strong winds.

The National Weather Service conducted a storm damage survey that occured from route PR-125 to the southwest of town of Moca through Barrio Cruz to route PR-111 on the east side of town.|After a damage survey and eyewitness accouts...the National Weather Service in San Juan Determined that a Tornado estimated at EF0 on the Enhanced Fujita Scale affected the Cuba sector and Barrio Cruz neighborhood during the early afternoon hours of Sunday August 7th with estimated winds of 65 to 75 mph.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

Aguadilla (TJBQ), 14 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The San Juan radar (TJUA), 111 km away, was scanning. The volume nearest the touchdown began at 17:33 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2011 tornado in Puerto RicoEvery tornado in Puerto Rico since 1950Warnings in force in Puerto Rico nowThe forecast where you are

1 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.