Tropical Atlantic and Tropical East Pacific Areas May through August 2016


Jorge Aguirre-Echevarria and Dan Mundell
Tropical Analysis and Forecast Branch
National Hurricane Center, Miami, Florida
NOAA National Centers for Environmental Prediction


Atlantic Ocean including the Caribbean Sea and the Gulf of Mexico

There were seven (7) non-tropical cyclone gale events that occurred between 1 May and 31 August 2016 in the area of high seas forecast responsibility (7N to 31N, west of 35W including the Caribbean Sea and Gulf of Mexico) of the National Hurricane Center's (NHC) Tropical Analysis and Forecast Branch (TAFB). The Caribbean Sea basin had the most gale events for this time period, but considerably less than last year.

Table 1

Table 1. Non-tropical cyclone warnings issued for the subtropical and tropical Atlantic Ocean, including the Gulf of Mexico and Caribbean Sea between 1 May and 31 August 2016.

Pre-Earl Caribbean Gale Event:

A strong tropical wave entered the eastern Caribbean Sea at about 1200 UTC on 31 July. The wave was moving rapidly westward along the southern periphery of the Atlantic subtropical high pressure. By 0000 UTC 1 August, low pressure of 1010 hPa had formed along the wave axis near 15N68W. (Figure 1) A tight isobaric spacing between the low pressure and the strong Atlantic high pressure induced east to southeast gale force winds of 25 to 35 kts from 15N to 18N between 66W and 69W with seas of 8 to 11 ft. (Figure 2 and Figure 3 ). The Ship BRASIL VOYAGER (C6ZJ8) just to the northeast of the low reported east winds of 35 kts. This report was very valuable to forecasters in confirmimg the presence of the gale force winds. By 1800 UTC on the same day the low had deepened some to 1007 hPa near 16.5N74W. The pressure gradient to its north remained tight per the surface analysis. (Figure 4)

An observation from ship KAROLINE N (A8PQ8) near the low center reported southeast winds of 35 kts at 18 UTC on August.1 near location 16N74W. During the night of 1 August, the low continued to deepen as was evident in the very cold cloud tops noted on satellite imagery from 0245 UTC 2 August with the METOP-B Advanced Scatterometer ASCAT pass showing quite an impressive coverage of strong gale force winds east of the low. (Figure 5). The low level circulation eventually became Tropical Storm Earl over the northwest Caribbean Sea at midday on 2 August.

Other Caribbean Gale Events

Other than the Pre-Earl gale event, there were three gale events in the favorable climatological area of strongest trade winds found over a portion of the southwest Caribbean Sea to the coasts of Colombia and northwestern Venezuela between 1 May and 31 August. The event that began at 00 UTC 17 June was rather short lived lasting for 12 hours. This particular event was confined from 11N to 13N between 74W and 77W, and included the Gulf of Venezuela. The pressure gradient between a narrow Atlantic high pressure ridge with axis roughly along 24N/25N, and low pressure across the Colombian basin initiated minimal gale force NE to E 30 to 35 kts winds with seas of 10 to 13 ft across that part of the SW Caribbean. (Figure 6) Note the tight gradient spacing just north of the coasts of Colombia and Venezuela between the 1016 hPa and 1012 hPa isobars.,