Tropical Depression and Heavy Rain in Puerto Rico, August 16 to 17, 2009

Name: Tropical Depression and Heavy Rain in Puerto Rico, August 16 to 17, 2009
Start: 2009-08-16T12:12
End: 2009-08-17T11:46
Location: Puerto Rico

August 16 to 17, 2009 · NWS SJU · 5 events in 5 counties and zones

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 5

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.

What happened

The episode as NWS SJU wrote it up.

A well organized tropical wave with an area of low pressure and significant thunderstorm activity moved offshore the African coastline on August 9th. The system moved northwest until reaching the southern Cape Verde Islands, then turned westward out into the open Atlantic. The system was upgraded to a tropical depression on August 11th, but easterly vertical wind shear kept the system from strengthening, and led to a reduction of thunderstorm activity which devolved the system into a remnant low pressure area on the 13th. By the 14th, the system redeveloped thunderstorm activity and redeveloped into a tropical depression, which strengthened into a tropical storm early on the 15th well to the east of the Lesser Antilles. Late on the 15th, a tropical storm watch was issued for the U.S. Virgin Islands, when the system was located about 910 miles east southeast of Saint Croix. At 5 am on the 16th, the tropical storm watch was extended to Puerto Rico, when the system was located about 850 miles southeast of San Juan. Soon afterwards, vertical wind shear from the west began to displace thunderstorms east and northeast of the center, beginning Ana's weakening trend. Also, the high pressure system steering Ana caused the system to accelerate westward. The weakening tropical storm Ana crossed the Lesser Antilles, and was downgraded to a tropical depression on the 16th at 5 pm, when it was located about 440 miles east southeast of Saint Croix. In spite of this, the tropical storm watch was kept in effect in case of any unexpected changes. Ana's local effects were mainly periods of heavy rain, gusty winds and cloud to ground lightning. Urban flooding, fallen trees, downed power poles and lines, rock slides, and power and water utility interruptions in several places. During the day on the 17th, aircraft reconnaissance determined that the system had dissipated southwest of Puerto Rico, as it no longer had a low-level circulation. At 5 pm, on the 17th, the tropical storm watch was discontinued for the U.S. Virgin Islands and Puerto Rico.

What forecasters said that day

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 San Juan, PR wrote its last area forecast discussion before the first event at Aug 16, 10:41 AM AST, 1 hour 31 minutes earlier.

Area forecast discussion, Aug 16, 10:41 AM AST, 1 hour 31 minutes before

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Hazardous weather outlook, Aug 16, 6:10 AM AST, 6 hours 2 minutes before

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The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 heavy rain, 2 tropical depression. Local standard time, as filed.

Heavy Rain, Toa Alta

When: August 16, 12:12 PM AST to 3:20 PM AST
Where: Toa Alta County, 2.91 mi NNW of Toa Alta
Reported by: Emergency Manager
Coordinates: 18.388, -66.250

Street flooding was reported by 911 in Rio El Mandril sector of Toa Alta.

Tropical Depression, Southeast

When: August 17, 5:00 AM AST
Where: Southeast forecast zone
Reported by: C-MAN Station

NOAA NOS Yabucoa Station indicated a wind gust of 42 mph from the east in association with Tropical Depression Ana.

Heavy Rain, San Juan

When: August 17, 7:46 AM AST
Where: San Juan County, 4.79 mi N of San Juan
Reported by: Emergency Manager
Coordinates: 18.448, -66.063

Baldorioty de Castro Avenue was reported flooded between San Jorge and Del Parque streets.

Tropical Depression, Northeast

When: August 17, 10:06 AM AST
Where: Northeast forecast zone
Reported by: C-MAN Station

NOAA NOS Fajardo Station (FRDP4) indicated a wind gust of 40 mph from the southeast in association with Tropical Depression Ana.

Heavy Rain, Carolina

When: August 17, 11:46 AM AST
Where: Carolina County, 5.92 mi NW of Carolina
Reported by: Emergency Manager
Coordinates: 18.429, -66.015

Street flooding was reported by 911 near the school by Laguna Gardens, Baldorioty Avenue.

What these are

Heavy Rain: Rainfall totals unusual for the place and season that did not produce a flood.
Tropical Depression: A tropical cyclone with sustained winds below 34 knots.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Puerto Rico in 2009 Every state in 2009 This day in weather history Warnings in Puerto Rico, August 2009 The 2009 hurricane season

Sources

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 2026-09-30. Each event’s entry at NCEI: 195253, 183779, 183944, 183777, 195254.