HEAVY RAINFALL HITS PUERTO RICO
AND U.S. VIRGIN ISLANDS

April 17-18, 2003

A strong upper level trough combined with abundant moisture to produce very heavy rainfall across a large part of Puerto Rico and the U.S. Virgin Islands. A surface low pressure system which developed over th e Southern Bahamas produced a steady flow of moist air from the south. Winds at lower levels were 20 to 30 knots through the event. A line of thunderstorms formed late Wednesday April 16th over the Atlantic waters to our northwest on a boundary ahead of the main trough associated with this surface low in the Bahamas. Thunderstorms continued to develop along the southern tip of this boundary as it progressed eastward and plenty of moisture continued to feed into our local area ahead of this boundary.

All of the ingredients were in place for a Flash Flood event to take place over Puerto Rico and the U.S. Virgin Islands. These conditions were forecast to remain over our local area for Thursday and Friday April 17th and 18th. Therefore, a Flash Flood Watch was issued overnight Wednesday into Thursday to give a heads up for flooding on Thursday. The first Flash Flood Warning was issued at 936 am to include mainly the Northeast municipalities of Puerto Rico. The threat of rapidly rising rivers and mud slides was emphasized. At 1030 am another Flash Flood Warning was issued for municipalities around Ponce. At 1230 pm the Flash Flood Warning for the Northeast was extended and expanded to include Humacao and Loiza. At 1252 pm another Flash Flood Warning was issued for the Southwest portion of Puerto Rico. At 130 pm the Flash Flood Warning for Ponce and Vicinity was extended. At 230 pm a Flash Flood Warning was issued to include a few more Eastern Interior municipalities. At 4 pm the Flash Flood Warning for the Northeastern Puerto Rico was extended for the second time until 10 pm. Rivers continued out of their banks and the soil was completely saturated increasing the threat of mud slides. At 4 pm the Flash Flood Warning for the South (Ponce and vicinity) and the Souhtwest was combined and extended until 10 pm. At 440 pm a Flash Flood Warning was issued to include Southeastern municipalities. At 545 pm the Flash Flood Warning for the Eastern Interior was extended until 10 pm. At 10 pm another Flash Flood Warning was issued to include all of the municipalities mentioned above (entire South and east and many municipalities across the Eastern and Central Interior) until 3 am. This trend continued through the day on April 17th with more warnings issued and extended.

The heaviest rainfall occurred on April 17th...but locally heavy rainfall continued on the 18th. Significant flooding was seen across many areas of Southern and Eastern Puerto Rico.


RAINFALL DATA

Excessive rainfall occurred across many areas. Several locations received over a half a foot of rain...with some areas receiving 1 to 2 FEET of rainfall! Most of this fell on the 17th. Here is a look at the heaviest rainfall totals across Puerto Rico for April 17-18, 2003.

MUNICIPALITY TOTAL RAINFALL
(rounded to nearest inch)
NAGUABO
22
LAS PIEDRAS
17
RIO GRANDE
16
LUQUILLO
14
PONCE
13
FAJARDO
12
CABO ROJO
8
JUANA DIAZ
7
VILLALBA
7
SAN LORENZO
7
MAUNABO
7

For a look at more rainfall totals across Puerto Rico, click here.


Heavy Rainfall was also seen across the U.S. Virgin Islands...where 2.54 inches of rain was recorded at St. Croix and 5.68 inches of rain was recorded at St. Thomas April 17th through the 18th.

IMPACTS

Severe flash flooding was concentrated across several municipalities of eastern Puerto Rico. The hardest hit municipalities were Fajardo, Rio Grande, Naguabo, Las Piedras, Juncos, Humacao and Luquillo. The governor of Puerto Rico, Sila Calderon, declared a state of emergency for these 7 municipalities.

The excessive rainfall forced several hundred families from their homes and caused an estimated $15 Million in damages to infrustructure and agriculture.

For a look at local flash flood reports, click here.


Images of Rainfall maps, etc...