Hurricane Erika 1997

Preliminary Report
Hurricane Erika
03 - 19 September 1997


Tropical Storm Ana (TS)
Hurricane Bill (1)
Tropical Storm Claudette (TS)
Hurricane Danny (1)
Hurricane Erika (3)
Tropical Storm Fabian (TS)
Tropical Storm Grace (TS)

Erika became a category three hurricane on the Saffir/Simpson Hurricane Scale, was the only named tropical cyclone of 1997 to form from a tropical wave at low latitudes, and just missed the islands of the northeastern Caribbean Sea.


a. Synoptic History

Erika was first tracked as a tropical wave and large area of disturbed weather moving westward from Africa to the eastern tropical Atlantic Ocean on 31 August. The system immediately showed evidence of a large-scale low-level cyclonic turning. But it was not until 3 September, when located about 1000 nautical miles east of the Lesser Antilles, that a low-level center was defined well enough for it to be upgraded to a tropical depression.

The depression quickly strengthened to tropical storm Erika on the 3rd and to a hurricane on the 4th as it moved mostly west-northwestward at 17 mph or so under the steering control of a well-established subtropical high pressure ridge. There was a hint of an eye as infrared satellite imagery showed a warm spot embedded in the deep convection over the center early on the 4th, but visible satellite imagery later showed a partially exposed low level center. The strengthening of Erika to a hurricane, based on drifting buoy data east of the Lesser Antilles, occurred under what appears to be an unfavorable shearing situation. However, deep convection soon reappeared over the center and strengthening continued, while Erika moved toward the west-northwest.

On the 5th through the 8th, the forward motion gradually decreased as the center of the hurricane came within about 75 nautical miles to the northeast of the northeastern-most Lesser Antilles...just far enough away for hurricane conditions to miss these islands. By the 8th, Erika had turned toward the north with a movement of only 8 mph as an amplifying trough over the western north Atlantic eroded the subtropical ridge and weakened the nearby steering currents.

Erika reached its peak intensity of 127 mph at 1800 UTC on the 8th and retained this wind speed for a period of about 24 hours, while it was located 300 nautical miles north of the Caribbean islands and started to accelerate northward. Reconnaissance aircraft and satellite imagery indicated an eye diameter of about 30 nautical miles during this time and the hurricane's radius of tropical storm force wind speeds expanded to 250 nautical miles.

The hurricane passed about 300 nautical miles east of Bermuda on the 10th and became embedded in westerly steering currents which caused a turn toward the east-northeast on the 11th and 12th. By this time, weakening had commenced due to a combination of cool sea surface temperatures and westerly winds aloft. Winds dropped below hurricane force on the 12th. However, Erika periodically retained deep convection near its center for another four days along with wind speeds between 52 and 69 mph while it moved mostly eastward across the north Atlantic. The center passed very near the western-most Azores on the 15th and tropical storm conditions were experienced in these islands. Erika then lost most of its deep convection and became extratropical by the 16th. It continued moving northeastward for several more days, followed by dissipation on the 20th while located about 200 nautical miles southwest of Ireland.

b. Meteorological Statistics

The NOAA Gulfstream high-altitude jet flew missions which resulted in data available for the 0000 UTC NCEP model runs on the 4th and 5th. This was when Erika was threatening the Caribbean islands and several days in advance of the recurvature across the north Atlantic. This data set provides an opportunity to evaluate the impact of synoptic-scale high-altitude dropsonde missions.

A NOAA drifting data buoy reported a 69-mph wind speed at 1600 UTC on the 4th, when Erika was located some 500 nautical miles east of the Lesser Antilles. The best track takes Erika to a hurricane at 1800 UTC based on this report, although there is considerable uncertainty about the accuracy of drifting buoy wind measurements as well as the method used to adjust the wind speed to the 10 meter level.

There were no reports of tropical storm force or higher sustained winds from the islands of the northeastern Caribbean as Erika passed nearby. The highest report received was 37 mph sustained wind speed with gusts to 47 mph from St. Thomas in the U.S. Virgin Islands on the 7th, when Erika was centered 125 nautical miles north-northeast of this location. There were, undoubtedly, stronger winds over the higher terrain of the islands from the Virgin Islands east and southward through Antigua and Montserrat.

NOAA research aircraft dropped GPS dropsondes into the eye wall on the 7th and 8th, as Erika was strengthening to its maximum intensity. While maximum 700-millibar flight level winds were near 127 mph late on the 8th, the vertical wind profile obtained near the eye wall showed that wind speeds between 150 and 1500 meters reached nearly 50 percent higher. The wind speed from this dropsonde nearest to the surface (approx. 15 meters) was 135 mph and the best track surface wind speed of 127 mph is based on this data.

The highest sustained surface wind report seen from the Azores was 30 mph with a gust to 45 mph at Lajes Air Base at 1900 UTC on the 15th as Erika's center was passing 180 nautical miles to the northwest. A report from Flores at 2300 UTC on the 15th gave a gust to 87 mph. A report from Lajes showed a gust to 105 mph from a 200-foot tower.

1. Rainfall Data

The largest rainfall total reported from the Virgin islands is 3.28 inches from St. Thomas

A storm rainfall total of 2.35 inches was also reported from Flores, Azores.

c. Casualty and Damage Statistics

There were 2 deaths attributed to Erika; 2 in Puerto Rico.

The only effects to Puerto Rico were from the large waves and swells generated by the hurricane. Two surfers died in the northern and eastern waters due to the high wave action. Most of the islands of the northeastern Caribbean suffered minor damage from wave action and there was likely minor wind damage at higher elevations. The general mood as expressed in the media was one of relief that a dangerous hurricane had turned north and missed the islands.

The passage of the hurricane caused the lower-tropospheric winds to blow from the southwest and advect a cloud of falling ash over Antigua from the active volcano in Montserrat.

Maximum Intensity For Hurricane Erika
03 - 19 September, 1997

Position Pressure
Wind Speed
Lat. (°N) Lon. (°W)
09/0600 25.2 61.4 946 125 Category 3 Hurricane