EF0 Tornado — Moca, Puerto Rico

2011-08-07 · near Moca, Moca, Puerto Rico

Event narrative

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.

Wider weather episode

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.

View location on OpenStreetMap → (18.3789, -67.0956)

Source: NOAA Storm Events Database, event_id 340522. Narrative written by the NWS forecast office that issued the report.