Tropical Storm — Vieques, Puerto Rico

2011-08-22 · Vieques, Puerto Rico

Event narrative

Downed power lines blocked Buena Vista street, Barrio Caon in the municipality of Vieques.

Wider weather episode

Irene was a quite large and impressive tropical wave during most of its journey across the Atlantic Ocean during the week of August 14-20, 2011. For most of this time the wave was nearly surrounded by dry air and with enough vertical wind shear to ensure that any intensification would be slow. Its forward speed of 20 mph somewhat aided the shear in keeping it weak. Irene made landfall over mainland Puerto Rico at 125 am AST on August 22, near Punta Santiago then Luis Munoz Marin International Airport at San Juan recorded its highest wind gust of 59 mph at 218 am AST. At 300 am AST (0700 UTC) the center was estimated to be 10 miles southwest of San Juan with 70 mph sustained winds, mainly over the Atlantic waters north of the city.

By 500 am AST doppler radar had indicated winds sustained up to 72 knots (83 mph) only 500 to 600 feet above the water. Irene was then officially upgraded to a hurricane though a hurricane warning had already been issued for the region. With the hurricane center moving offshore about this time the strongest winds (north of the center) also moved away from shore. At 536 am AST the buoy near Arecibo recorded its highest wind gust of 37 knots (43 mph). At 900 am AST the center of Irene was directly north of the west coast of Puerto Rico but the hurricane force winds were well offshore with an obviously developing eye on radar.

Puerto Rico was under the effects of Tropical Cyclone Irene from early Sunday August 22 through late Wednesday August 24. Irene made landfall as a tropical storm during the early morning hours of Monday August 22, intensified overland and became a hurricane over northern Puerto Rico around 500 am Monday, before exiting into the Atlantic later that morning. Irene's most siginificant impact was the heavy rainfall. The first rainbands entered eastern Puerto Rico early on Sunday and persisted through midnight on Wednesday, although additional rainfall was received across some of the east municipalities through Thursday morning August 25. Locations like Gurabo across eastern interior Puerto Rico experienced significant 48 hour rainfall accumulations, with an estimated return period of around 50 years.

Shortly after Irene's center passed by San Juan on August 22 there were 800,000 homes without electric power and 118,000 without water service. The storm surge from Irene, as expected, was very minor. The highest surges measured were at Esperanza (Vieques) and Fajardo and reached 1.6 feet between 100 am and 200 am (0506z and 0530z respectively). This was during the time that the center of Irene was moving inland over Eastern Puerto Rico.

Damage from flooding was extensive across the region from Irene, however, though wind caused widespread damage it was relatively minor compared to a more significant hurricane. Numerous trees were blown down very early on Monday morning from Fajardo to San Juan Metro. Downed trees were reported to block highways in Gurabo, Adjuntas, Caguas while a down power pole lay on Highway PR-176 in Cupey.

On August 27 Puerto Rico had been declared a major disaster area, and by September 3 additional municipalities were added to provide aid to those impacted, and still more on September 13. In all, there were 29 municipalities approved for individual assistance to individuals and households while 37 municipalities were designated for public assistance to state and local governments and certain private nonprofit organizations for emergency work and the repair or replacement of disaster-damaged facilities.

Source: NOAA Storm Events Database, event_id 340459. Narrative written by the NWS forecast office that issued the report.