Category 4 Hurricane Matthew Continues Northwest Toward Greater Antilles

By: Bob Henson , 12:00AM GMT on October 3,2016



 

Short-term ups and downs in Category 4 Hurricane Matthew continued on Sunday afternoon, as the storm drifted northwest toward an expected destructive encounter with Haiti, Jamaica, and Cuba. As of the 8 pm EDT Sunday advisory from the National Hurricane Center (NHC), Matthew’s top sustained winds were 145 mph, a slight increase from Sunday morning but still down from Matthew’s peak of 160 mph on Friday night. It’s typical for hurricanes as strong and mature as Matthew to experience minor fluctuations in intensity, sometimes several times in a day. A more substantial drop in intensity lasting a day or more can occur when a major hurricane’s eye shrinks so much that a secondary eyewall forms around it, eventually replacing the original eyewall. Thus far, Matthew has avoided a classic eyewall replacement cycle (ERC), although there are signs that a secondary feature may have developed Sunday without causing a significant intensity drop, as noted by wunderblogger Steve Gregory.

The puzzling batch of intense showers and thunderstorms (convection) located more than 100 miles east of Matthew continued through the day Sunday (see Figure 2). At times over the weekend, this feature has been larger and more intense than the convection around Matthew itself. NHC forecaster Richard Pasch referred to this as a “persistent, but inexplicable, cluster of deep convection” in NHC’s Sunday morning discussion of Matthew, adding that “the effect of this feature on Matthew's intensity evolution is unknown.”


Figure 1. MODIS satellite image of Matthew taken at 11:30 am EDT Sunday, October 2, 2016. At the time, Matthew was a Category 4 storm with 145 mph winds. Image credit: NASA.


Figure 2. Enhanced infrared image of Matthew as of 7:15 pm EDT Sunday, October 2, 2016. Image credit: NOAA/NESDIS.

It appears that Matthew has a very tight core of peak winds surrounded by much-less-strong winds. NOAA buoy 42058 has been located less than 50 miles from Matthew’s center for most of the day Sunday, yet its top sustained winds remained just below 60 mph through 5 pm EDT (see Figure 2). NOAA reports that Matthew’s hurricane force winds extend out to 35 miles from Matthew’s center, with tropical storm force winds extending out up to 205 miles.


Figure 3. Top sustained winds observed at NOAA buoy 42058 over the past five days. Hurricane Matthew was passing less than 50 miles south of the buoy on Sunday afternoon, when sustained winds topped 45 knots (52 mph). Image credit: NOAA/National Buoy Data Center.

Serious threat for Jamaica, Cuba, and Haiti in next 48 hours
We will likely be talking about Matthew throughout the upcoming week, but the most immediate concern is for the western Greater Antilles. Now moving northwest at about 5 mph, Matthew is expected to arc north-northwest or north as it approaches the islands. Hurricane Warnings are in effect for Haiti, Jamaica, and the eastern Cuban provinces of Guantanamo, Santiago de Cuba, Holguin, Granma, and Las Tunas. The official NHC forecast, and the prevailing view from our top forecast models, is for Matthew to pass somewhere between eastern Jamaica and western Haiti on Monday night and to cross easternmost Cuba on Tuesday.

Matthew has the potential to strengthen en route to Jamaica and Haiti, especially if an upper-level outflow channel develops on its south side, as suggested by data on Sunday afternoon. Satellite imagery late Sunday afternoon showed a sharpening eye, and a region of very high oceanic heat content is located below Matthew’s expected path on Sunday night and Monday (see Figure 4 below). It is not out of the question that Matthew could regain Category 5 strength en route to Jamaica and Haiti, a truly frightening prospect. Assuming Matthew largely avoids the high mountains of Jamaica and Haiti, it is likely to hit eastern Cuba as one of the region’s most intense landfalling hurricanes in decades.


Figure 4. Tropical cyclone heat potential, an index of the amount of heat in the upper ocean, for the Caribbean as of October 1, 2016. Matthew’s position at 5 pm EDT October 2, 2016 is shown as the magenta hurricane symbol with a “4” in it. The hurricane is about to enter a region with high oceanic heat content, in excess of 100 kilojoules per square centimeter (orange colors), which may aid in intensification. Image credit: NOAA/AOML.

A rare northward-mover
A northward track into the Greater Antilles would be very rare for a hurricane as strong as Matthew. The only two analogs in the last few decades happen to be two other October storms: Sandy (2012) and Hazel (1954), neither of which reached the islands at Category 4 strength. As Matthew approaches, phenomenal rainfall rates can be expected, especially east of Matthew’s center, as southerly winds slam against south-facing mountains and hillsides. NHC is warning that rainfall could total as much as 40” in parts of southern Haiti and the southwest Dominican Republic, with widespread 5” - 15” totals expected elsewhere across Haiti, parts of Jamaica, and eastern Cuba.

It’s possible that Matthew will continue on its northwest course and turn north a bit later than models are predicting, which could bring the center over or close to eastern Jamaica rather than westernmost Haiti. This would greatly increase the potential impact on Jamaica, which has experienced only three direct hits from hurricanes of any strength in the past 65 years. In any event, Haiti--a nation where deforestation has made the landscape extremely vulnerable to flooding and landslides--is almost certain to experience Matthew’s extremely heavy rains, which are expected to extend well east of the center (especially if the batch of intense convection well east of Matthew retains its identity). Storm surge may also be a significant concern, perhaps as high as 7 to 11 feet on the far southeast coast of Cuba and 7 to 10 feet on the south coast of Haiti.


Figure 5. Projected total rainfall from Hurricane Matthew over Jamaica, Haiti, the Dominican Republic, and eastern Cuba as of Sunday afternoon, October 2. Image credit: Greg Carbin, NOAA/NWS Weather Prediction Center (WPC), @GCarbin.

The Bahamas and beyond
Little has changed in the prognosis for The Bahamas, which are likely to be hit hard by Matthew. A Hurricane Watch is now in effect for the southeastern Bahamas as well as the Turks and Caicos Islands. Matthew is expected to move north across the heart of The Bahamas from Wednesday into Thursday. Even if Matthew has weakened to a Category 3 hurricane by then, it could easily restrengthen, as wind shear should remain low through at least midweek (around 10 knots or less) mid-level relative humidity will remain high (70% or more), and sea-surface temperatures will be at near-record levels around 29-30°C (84-86°F). Ample deep oceanic heat throughout the Bahamas would help sustain Matthew even if it moved slowly and churned up deeper waters.

Beyond midweek, the outlook for Matthew remains fairly murky. The operational runs of the GFS and European models both take Matthew on a curving northeastward path that parallels the Southeast U.S. coast, drawing within 100 miles of the North Carolina coast by Saturday or Sunday before moving further offshore. The 12Z Sunday UKMET model--the other of our best three track models--is the outlier, bringing Matthew northwest from the Bahamas toward central Florida by next weekend. The 50 members of the Euro ensemble runs from Sunday (see Figure 6) continue to indicate the possibility of a landfall along the U.S. Mid-Atlantic or Northeast coast (or the south coast of Nova Scotia, Canada) a week or more from now, although most of the members keep Matthew offshore north of North Carolina. The 18Z GFS ensemble shows only a small minority of runs producing any U.S. landfall, mainly in the Outer Banks of NC.

For now, Matthew’s track beyond the Bahamas is still uncertain enough that coastal residents from Florida to Canada should be on the alert for possible impacts in a few days, especially given this hurricane’s strength and breadth. Note that long-range computer models may overestimate Matthew’s strength north of the Carolinas. Much cooler waters there would likely bring Matthew below major-hurricane strength in less than a day’s time, although it could still be a strong hurricane or post-tropical cyclone with huge surf as far north as Canada. Beach erosion may become a major issue later this week if Matthew takes its time moving northward off the East Coast.

Jeff Masters will be back on Monday morning with our next update on Matthew, as well as more background on the hurricane history of Jamaica, Cuba, and Haiti. Meteorologist Steve Gregory is making regular updates on Matthew.

Bob Henson


Figure 6. The 70 forecasts from the 12Z Sunday European (ECMWF) model ensemble (top) and 18Z Sunday GFS model ensemble (bottom). Image credit: Climate Forecast Applications Network (CFAN).