Hurricane Maria

The peak of the 2017 Atlantic Hurricane season continues to be active. Another major hurricane has had significant impacts in the Eastern Caribbean. Hurricane MARIA made landfall in Dominica on Monday evening as a category five hurricane with maximum sustained winds near 160 mph, with higher gusts. Winds of this strength are capable of producing catastrophic damage. Early reports from Dominica confirm that widespread wind damage indeed occurred.

In addition to violent winds, tropical cyclones present serious water hazards. Coastal areas are flooded as the ocean is blown onshore, combining with astronomical tides – this is known as a storm tide. This flooding can be accompanied by large battering waves at the immediate shoreline. Furthermore, heavy rains intrinsically linked to tropical cyclones can result in life-threatening flash flooding and mudslides. Both of these hazards also affected land in Dominica.

Météo-France Radar Imagery from Martinique and Guadelupe‏: Hurricane Maria passing over Dominica 18 UTC 18 Sep – 08 UTC 19 Sep 2017. The purple and blue colors indicate light rain, while the green and yellow colors indicate heavy rain. Source.

At landfall in Dominica, the core of category five hurricane MARIA was small. Hurricane force winds extended at most 30 miles from the center. But the spiral bands, packing torrential rains and damaging tropical storm force winds extended over Martinique and Guadelupe.

The high terrain on Dominica was able to weaken MARIA somewhat as it crossed that island. However, emerging over the high sea surface temperatures of the Caribbean and remaining in a favorable atmospheric environment, MARIA was able to quickly regain strength.

As is common with powerful hurricanes, particularly those that have small cores, an eyewall replacement cycle began on Tuesday evening. This is when spiral bands organize into an outer eyewall structure surrounding the original eyewall. The outer eyewall then intensifies at the expense of the inner eyewall. The inner eyewall eventually dissipates and the outer eyewall contracts. This typically ends with a slightly weaker hurricane with a larger core of violent hurricane force winds.

National Weather Service Radar Imagery from Puerto Rico as MARIA passes near St. Croix. On the right, the inner eyewall is highlighted in pink, and the outer eyewall in purple. In both images, the lighter rain is in blue and green with heavier rain in yellow and orange colors. Imagery at 0344 UTC 20 Sep 2017.

In the pre-dawn hours of Wednesday morning, the outer eyewall of MARIA was strengthening and the inner eyewall weakening. The resulting broadened core of MARIA was now wide enough to bring the violent hurricane force winds of the outer eyewall to St. Croix of the US Virgin Islands.

National Weather Service Radar Imagery from Puerto Rico just before the time of landfall in Puerto Rico. Here, light rain is blue and green colors, heavy rain in the yellow and orange colors. Imagery at 0950 UTC 20 Sep 2017. Radar imagery from Puerto Rico ended at this time for reasons related to the hurricane.

The typical progression of the eyewall replacement cycle was interrupted just before completion as MARIA came ashore in Puerto Rico near sunrise Wednesday morning, as a category four hurricane with maximum sustained winds near 155 mph – still capable of producing catastrophic wind damage, coastal flooding, and life-threatening inland flash flooding. Adverse weather spread across all of Puerto Rico through the morning, leaving widespread wind damage and floods.

The much more substantial terrain of Puerto Rico significantly disrupted the core of MARIA, and the hurricane has emerged into the Atlantic and has maximum sustained winds near 115 mph. This remains a dangerous major hurricane.

Remaining in a favorable environment of light wind shear and high sea surface temperatures, MARIA is now re-organizing as it tracks northwestward, offshore of the north coast of Hispaniola. The Turks and Caicos Islands are next at risk of direct impacts from the core of violent winds, while adverse weather extends across the Dominican Republic, Haiti, and the southeastern Bahamas Islands.

[See the latest Forecast Track for MARIA from the NHC]

MARIA is expected to pass near the Turks and Caicos Islands Friday Morning as a major hurricane capable of producing extreme to catastrophic wind damage, coastal flooding, and freshwater flooding. Late on Friday, MARIA is forecast to turn more northwestward, and then northward over the weekend. This takes the track of MARIA away from the Bahamas and the hurricane is expected to track between the US East Coast and Bermuda in the 3-5 day period.

Swells from IRMA, JOSE, and now MARIA have kept rough seas in Bermuda’s marine area for most of September. Bermuda should continue to closely monitor the progress of MARIA as it turns northward in the long range. At the moment, MARIA’s impacts on Bermuda appear to be a continuation of rough and hazardous seas in the marine area while winds may increase into the moderate-strong range as MARIA passes to the west on Tuesday.

Follow official updates from the Bermuda Weather Service and the National Hurricane Center.


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