Hurricane Maria continues to intensify this evening as it makes approach to USVI and Puerto Rico

Hurricane Maria…after devastating the island nation of Dominica with maximum sustained winds of 165 mph and gusts over 190 mph…is now threatening the highly populated US territory of Puerto Rico and also the US Virgin Islands as a Category 5 hurricane. Maximum sustained winds are near 175 mph at 8 pm EDT and the hurricane continues to intensify. It is now the 9th most intense hurricane on record by minimum central pressure (906 millibars as extrapolated by the USAF Reserve Hurricane Hunters; more than 100 mb lower than Earth’s average sea level pressure). For comparison, the most intense hurricane on record in the North Atlantic was 2005 Hurricane Wilma (882 mb) and 2005 Hurricane Katrina by comparison had a minimum central Pressure of 902 mb at its peak with winds of 175 mph (ranked 7th by pressure). There are signs the hurricane is continuing to intensify. The next hurricane hunter plane will arrive in the storm by 10:30 pm EDT.

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Mid-level water vapor imagery by the GOES 16 satellite (non-operational, in testing). It shows the very powerful circulation of Maria and the very dry/warm eye in the center (image at 8:27 pm EDT).

As of now, there is absolutely NOTHING to stop the power of the storm, except internal, inner core processes (like an eyewall replacement cycle). The waters under Maria are 1-1.5 degrees C (~2-3 degrees F) above normal and the oceanic heat content (includes warmth with depth) and resulting tropical cyclone heat potential is MUCH above normal along the track.

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5-day Track forecast for Maria (NHC).

The eye will pass near or over the island of Saint Croix late tonight and make landfall in Eastern Puerto Rico tomorrow morning. Both landfalls are expected at Category 5 intensity with gusts over 185 mph in the inner core (particularly northern eyewall). In addition to the violent winds, rainfall of 12-18+ inches are possible over the USVI and Puerto Rico, along with landslides in the mountainous terrain, where winds may also be even more violent than near sea-level.

Needless to say, this is a truly horrific situation evolving for a territory of 3.5 million people; and a territory still recovering from much weaker hurricane impacts from Irma two weeks ago. USVI such significant damage from Irma as well.

I will an update on Maria later this evening as new data comes in.

–Meteorologist Nick Humphrey

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The North Atlantic Tropics Looking to become Active Again This Weekend or Next Week

It’s August and with that it’s time for the North Atlantic to show its tropical cyclone “muscle”. Tropical waves become more numerous as mesoscale convective systems form over the tropics of West Africa and race off into the open Atlantic; their mid-level “vorticity” or spin the seed for possible further development. The National Hurricane Center in Miami has pegged one Thursday with an 80% chance of development between now and Tuesday (40% chance between now and Saturday).

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Shortwave infrared image (sometimes known as “nighttime visible”) taken at 8 pm EDT Thursday. This shows a cloud mass moving off West Africa associated with a new tropical wave south of the Cape Verde Islands. (NOAA)

Mid-range models suggest the system will develop possibly into a depression or tropical storm, moving generally westward toward the Lesser Antilles heading toward Tuesday. Much more on what will happen will depend on the system’s development. Mid-level dry air brought in from the Sahara Desert will be an issue for this system as it approaches the Lesser Antilles if it moves north of 15N. As far as upper-level winds, forecast shows a modestly favorable environment for development, but details will wait until down the road. Water temperatures in this part of the Atlantic – known as the Main Development Region (MDR) – are running up to 1.5 C (~3 F) above average with abundant warm sea surface temperatures above 26 C (79 F) west of 35 W.

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Current Sea Surface Temperatures over the tropical Atlantic Ocean. The orange-red and red shades indicate temps at and above 26 degrees C. (Wunderground.com)

Because of the strong semi-permanent “Bermuda High” expected to dominate the Central and Western Atlantic next week, this system will need to be watched by interests in the Western Atlantic Basin for potential impacts in case it does not curve northeastward out to sea because of the subtropical high pressure system to its north (assuming it develops).

Also of interest is a system in the Eastern Caribbean Sea. It is in a more hostile environment (shear and dry air main problems) and only has a 40% chance of development over the next 5 days.

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Shortwave IR image at 8:45 pm EDT showing generally disorganized thunderstorm activity associated with a tropical wave in the Eastern Caribbean. (NOAA)

The Atlantic has been running about a month ahead of schedule on named storms, but has been dead quiet on hurricanes. The 1966-2009 average for the first hurricane in the basin is coming up (August 10th), but given recent years of activity, the Accumulated Cyclone Energy (ACE) thru Aug. 2nd is running at its lowest level in the basin since 2009. But still 90% of the ACE on average occurs from here on out, so much can still happen, especially given the lack of one otherwise major hindering presence in El-Nino.

I’ll keep track of these disturbances in the coming days and have more for you if they develop into organized systems. Stay tuned!