Report on the Windstorm at the Mayaguez Eugenio Maria de Hostos Airport on the afternoon of Thursday July 1, 2010

During the late afternoon of Thursday, July 1, 2010, the National Weather Service Forecast Office received reports of very strong winds that were observed at the Mayagüez airport. These strong winds caused considerable damage  to approximately nine portable tents that had been installed at the airport, as part of the medical support for the Mayagüez 2010 Central American Games. The Cape Air observer on duty called the National Weather Service (NWS) Office, indicating that he had measured winds of around 40 knots (44 mph), and a sudden gust of 72 knots (80 mph), but that no funnel cloud, tornado, or hail was observed at the time. See preliminary surface observations from the Mayaguez airport for the period from 450 PM AST to 507 PM AST below. No additional observations were available for the remainder of the afternoon.

             SACA32 TJMZ 012100
             METAR TJMZ 012050Z 07010KT 2SM TSRA OVC025 32/30 A2998 RMK FQT LTG NE   TSB45 TS E MOV W 

SAZZ40 TJMZ 012100 RRT
METAR TJMZ 012107Z 34028G40KT 01SM +TSRA OVC020 27/27 A2998 FRQ LGTCG
Several NWS staff members visited the Mayagüez airport and surrounding area on the afternoon of July 9, 2010. The visible damage was surveyed and conversations were held with the Cape Air observer and Luis Sáez, Department of Health Coordinator, who observed the event at the airport from inside his vehicle. His description of the event was that the “sky changed colors from gray to black, and the rain intensity became stronger, as if a wall of rain was moving from side to side. Suddenly, the trees inside the runway perimeter started to twist, the tents roofs were lifting away, and my vehicle was being shaken by the wind.” The Cape Air observer indicated the storm lasted about 5 minutes.

Based on a visual survey, the area that suffered the most significant damage was located at the airport and its vicinity with the following damage noted:

  • The tents were blown off and pushed against the airport fence, causing damage to the fence.
  • A metal railing attached to the ground and to a walk concrete way was lifted.
  • One airport customer facility sliding doors were taken off their tracks.
  • An aircraft that was not tied down and whose tail was unlocked, was turned sideways under the wind gusts.
Many trees around the airport had snapped branches, indicative of a wind gust of 50 to 60 mph.  
The Puerto Rico Electrical Power Authority has a wind sensor installed at one of their facilities located about 1600 meters southwest of the airport. Their sensor recorded a wind gust of 36 mph from the north (360 degrees) at 509 pm AST. This observation is very consistent with the METAR observation take by the Cape Air observer at 507 pm AST.
The WSR88D TJUA 0.5 degree elevation velocity images at 504 pm indicated outbound speeds of 31 knots (36 MPH) at 8,485 feet AGL (Above Ground Level)  just to the north of the airport, and 22 knots (25 MPH) at the airport. The reflectivity images showed a value of 61 dbz  just north of the airport at 458 pm. The Vertically Integrated Liquid (VIL) value of 50 kg/m2 at 453 pm decreased to 39 kg/m2 at 504 pm. The storm top at 458 pm had reached a height of 46 thousand feet over Mayaguez, however by 516 pm the top had decreased to 40 thousand feet.    
Images from the University of Puerto Rico Mayagüez Campus Experimental Casa Radar at CROEM school in Mayagüez which were made available to us during our survey visit,  displayed an interesting signature at 507 pm, which initially resembled that of a bounded weak echo region (BWER). However, after further analysis, what can be reasonably inferred was that it was a line of very heavy rain.
Given the data available, and the reports from the field, this wind event could be classified as a wet mini-microburst. The damage surveyed was indicative of straight line winds, and limited to the general airport area. The observed tree branch damage was consistent with what is typically observed with wind gusts of 50 to 60 mph.  


TJUA Doppler Radar loop

                                            WSR88D loop




 Additional Images

Damaged hospital tents Damaged hospital tents installed within the airport grounds. Courtesy of Luis Saez from NDMS DMAT
Snapped tree branches along the eastern section of Mayaquez Airport Snapped tree branches along the eastern part of the Mayaguez Airport
Snapped tree branches along the southern and west side of Mayaguez Airport Snapped tree branches along the southern and west side of the airport.
Mayaguez airport facility outside sliding doors off their tracks  Mayaguez airport facility outside sliding doors off their tracks
Airport fence along southwest periphery Airport fence along southwest periphery
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