Hurricane Warnings for Haiti, Jamaica as Category 4 Matthew Restrengthens

Despite its unorthodox structure, Hurricane Matthew remains a formidable hurricane in the southern Caribbean Sea and an increasing threat to parts of Haiti, Jamaica, and Cuba. Matthew briefly attained Category 5 intensity late Friday, when its top sustained winds hit 160 mph--only 36 hours after Matthew was still a tropical storm. By early Saturday afternoon, Matthew’s peak winds had were at 140 mph, but they have since resurged to 150 mph as of the 5 pm EDT advisory from the National Hurricane Center. Matthew is now a high-end Category 4 hurricane.

As noted by Jeff Masters in our morning post, only a few hurricanes in the Atlantic have bolted from tropical storm to Cat 5 intensity in less than two days. Hurricane Wilma of 2005 and Hurricane Patricia of 2015 accomplished the feat in 24 hours; Hurricane Felix of 2007 did it in 30 hours; Hurricane Rita of 2005 and Hurricane Andrew of 1992 did it in 36 hours; and the Great Labor Day Hurricane of 1935 did so in 42 hours.


Figure 1. Enhanced infrared satellite image of Matthew at 2115Z (5:15 pm EDT) Saturday, October 1, 2016. Image credit: NOAA/NESDIS.

Menacing yet quirky
For such a powerful hurricane, Matthew has quite an odd structure. The most unusual feature is the persistent swath of intense showers and thunderstorms (convection) well east of its center, as evident in Figure 1 above. This feature has been in place for most of Matthew’s life as a tropical cyclone, and it may have played a role (yet to be determined) in its rapid intensification. For much of Saturday afternoon, this area of convection was actually larger and stronger than the convection around Matthew itself.

Hurricane Hunters on Saturday afternoon continued to find Matthew bearing a closed, fairly small eye that was just 8 nautical miles in diameter. Eyewall replacement cycles, which are fairly common with intense hurricanes, can produce a weakening for a day or so as the inner eye decays and the outer one gradually takes over. There was some evidence on Saturday that Matthew was trying to form a secondary eyewall further from its center, but this had not yet happened by late Saturday afternoon. Outside of rain-contaminated areas, the strongest near-surface winds detected by the Hurricane Hunters using the SFMR radiometer were around 130 knots (150 mph), and peak flight-level winds were around 135 knots (155 mph).

A dire situation for Haiti
After moving mainly west-southwest for the past day, Matthew carried out a very tight cyclonic (counterclockwise) loop on Saturday afternoon--most likely a prelude to its long-expected northward turn. At 5 pm EDT, Matthew was drifting northwest at just 3 mph. Assuming Matthew’s northward motion picks up as expected on Saturday night, we should soon have a better sense of which parts of the Greater Antilles will be most at risk from Matthew. The most immediate threat is to Jamaica and Haiti, which Matthew is expected to be approaching by early Monday. It is very rare for hurricanes this strong to strike either nation from the south, an angle of approach that would maximize the storm-surge potential along south-facing coasts.

Extremely heavy rains will occur around Matthew, and in particular on its right-hand (eastern flank), where fierce southerly winds will slam into south-facing mountains and hillsides. Rainfall east of Matthew’s center could be even more widespread and heavier than with other hurricanes of this size and strength because of the massive slug of convection and moisture well east of its center, as discussed above.


Figure 2. All hurricanes that are known to have passed through the shaded circle with at least Category 3 intensity. The only major hurricanes that took a south-to-north track similar to the forecast for Matthew were Sandy (2012), which briefly attained Category 3 strength before striking eastern Cuba, and Hazel (1954), which struck southwest Haiti as a Category 3 storm. Up to 1000 Haitians died as a result of Hazel, and the nation’s economy was hobbled for years afterward. NOAA’s hurricane data base extends back to the mid-1800s. Both Hazel and Sandy were October hurricanes that went on to affect much of the U.S. East Coast. Image credit: NOAA


The 12Z Saturday runs of our best track models--the GFS, European, and UKMET models--all bring Matthew between Jamaica and Haiti, as reflected in the latest official NHC track. This path would reduce the risk for Jamaica but heighten it for Haiti, where deforestation greatly enhances the potential for devastating floods and landslides. I’m especially concerned about the mountainous Tiburon Peninsula of southwest Haiti, which is most likely to experience the strongest winds and heaviest rains. NHC warns that rainfall could total 15” to 25” in southern Haiti, with localized amounts as high as 40” possible. Given Haiti’s extreme poverty (the nation is still recovering from its catastrophic earthquake of 2010), Matthew could produce a truly devastating blow. Heavy rains of 10” - 20” will also affect parts of eastern Jamaica and the Dominican Republic. A Hurricane Warning is now in effect for all of Jamaica and for southern Haiti, with a Hurricane Watch for northern Haiti.


Figure 3. NHC track forecast for Hurricane Matthew as of 5 pm EDT Saturday, October 1, 2016.

If Matthew threads the needle between eastern Jamaica and western Haiti, it will largely avoid disruption from mountains that exceed 6000 feet in height in both areas. This would allow Matthew to retain most or all of its strength as it approaches easternmost Cuba late Monday. Most of Cuba should experience the less-intense west side of Matthew, but a Hurricane Watch is in effect from Camaguey to Guantanamo province. Matthew could make landfall very close to Guantanamo Bay, where some 700 U.S. military personnel and family members were preparing on Saturday night for evacuation to Pensacola, Florida. Although Sandy was barely a Category 3 when it struck just west of Santiago de Cuba in 2012 from the south, it was the strongest hurricane to hit eastern Cuba in half a century, destroying tens of thousands of homes and taking at least 11 lives.

Longer-term outlook for Matthew
Models have converged somewhat on Matthew’s future track in the western Atlantic, but there remains plenty of uncertainty on critical points. Chances are that Matthew will be at least partially disrupted from its trek through the Greater Antilles. However, our top intensity models agree that it will likely restrengthen once it reaches The Bahamas. Conditions will remain very supportive for Matthew over The Bahamas on Tuesday and Wednesday, with very low wind shear, record-warm sea surface temperatures, and a moist atmosphere to work with. Residents of The Bahamas would be well advised to start making preparations, as hurricane watches could be required as soon as Sunday. Right now it appears the eastern Bahamas are most at risk of being affected by Matthew’s more dangerous east side, but very heavy rains and high winds could overspread many of the islands on Tuesday or early Wednesday.


Figure 4. The 70 forecasts from the 18Z Saturday GFS model ensemble (top) and 12Z European (ECMWF) model ensemble (bottom) continued to show a wide variety of solutions for the track of Matthew. The two models have grown closer together in their solutions compared to Friday. Both models indicated that Matthew could remain a major hurricane well into the northwest Atlantic, although model skill at intensity prediction drops markedly over time. Image credit: Climate Forecast Applications Network (CFAN).

Big questions on Matthew’s track later next week
Models agree very closely on Matthew’s general track into the Bahamas, but they strongly suggest that Matthew could slow down or angle toward the northwest by midweek as steering currents weaken. The next step in the Matthew saga will then be determined by two main influences. One is an area of low pressure about 600 miles east of the Leeward Islands, moving slowly west-northwest. NHC gives this area only a 20% chance of developing into at least a tropical depression by Thursday. Regardless of its status, it could give Matthew a pathway to move northeast and out to sea from the Bahamas. The other influence on Matthew’s long-term future is a strong mid-latitude upper trough that will be plowing toward the eastern U.S. by later next week. Models generally agree that the upper-level trough will pick up Matthew and cart it north and northeastward, but there is crucial disagreement on how far west its track might extend. Among the 20 members of the 18Z Saturday ensemble run of the GFS and the 50 members of the 12Z Saturday European (ECMWF) ensemble, a number of members haul Matthew along the U.S. East Coast at various points, with several tracks moving well inland. A number of other GFS and ECMWF ensemble members keep Matthew just off the East Coast without any direct landfall.


Figure 5. Track forecasts from the five European model ensemble members [gray lines] that most closely match the operational run [red line] during the first 72 hours, starting at 12Z Saturday, October 1, 2016. The red line is a version of the 12Z Saturday operational model track that has been adjusted and calibrated using a proprietary technique to account for systemic model errors. Image credit: Climate Forecast Applications Network (CFAN).


We cannot yet rule out the possibility of Matthew moving close enough to the Florida coast to produce major impacts. Among the five members of the “high-probability” Euro ensemble from 12Z Saturday (see Figure 5), two members take Matthew sharply westward across South Florida by next weekend and up Florida’s West Coast. The 12Z Saturday UKMET model also brings Matthew to the vicinity of South Florida by Thursday. Considering that the Euro, GFS, and UKMET are our top three track models, it’s clear there is still plenty of uncertainty in how Matthew may affect the U.S. later next week.

The bottom line:

Matthew poses a dire threat to the western Greater Antilles, especially Haiti. All residents should prepare as best they can for what could be the strongest northward-moving hurricane in living memory across the region.

The Bahamas may experience prolonged impacts from Matthew next week. The official NHC forecast brings Matthew through the islands as a Category 3, and it could be stronger. The duration of Matthew’s impact, and its exact track, are increasingly uncertain beyond Tuesday.

Models continue to indicate the potential for Matthew to affect any part of the U.S. East Coast from Florida to Maine later next week into the weekend. The bulk of model solutions keep Matthew just offshore, but a significant minority bring Matthew onshore, possibly as a strong hurricane. It is too soon to know exactly how the mid-latitude steering currents will evolve, so the range of potential landfall locations remains very wide.

Jeff Masters will be back with our next update by late Sunday morning. Wunderblogger Steve Gregory posted a Saturday afternoon update on Matthew, CAT 4 HURRICANE MATTHEW: THREAT TO US CONTINUES.

Bob Henson