|Above: Floodwaters surround homes in North Carolina’s Outer Banks, where Hurricane Maria brought a 2’ storm surge on Tuesday, Sept. 26, 2017. AP Photo/Ben Finley.
Tropical Storm Warnings and Storm Surge Warnings continued for much of North Carolina’s Outer Banks on Wednesday as Hurricane Maria—bumped back up from tropical-storm status at 11 am EDT Wednesday—began to slowly pull away from the coast. Maria’s center came within 155 miles of Cape Hatteras, NC early Wednesday morning, but the storm had begun angling away from the coast at 6 mph, to the north-northeast, as of 11 am EDT Wednesday. Maria brought winds near minimal tropical storm-force along the Outer Banks early Wednesday morning. The highest winds observed on Wednesday morning at the USCG station at Cape Hatteras, NC were 39 mph, gusting to 47 mph, at 12:36 am EDT. The Diamond Shoals buoy located 15 miles southeast of Cape Hatteras had peak sustained winds of 42 mph, gusting to 51 mph, at 2:50 am EDT. An observing site at Jennette's Pier in Nags Head, North Carolina, measured a sustained wind of 43 mph, gusting to 51 mph, late Wednesday morning.
According to the NOAA Tides and Currents Quicklook page for Maria, a peak storm surge of 2.8’ was observed at Cape Hatteras, NC near 2 am EDT Wednesday; the highest surge at Duck, NC was 2.0’ near 3 am. Storm surge heights of 1.5 – 2.0’ were observed Wednesday morning along the Virginia coast near Norfolk. Wednesday morning’s high water levels resulted in some overwash of NC 12, the only road into or out of the Hatteras-Ocracoke section of the Outer Banks.
Satellite imagery on Wednesday showed that Maria was a large and sloppy-looking storm, with its heavy thunderstorm activity confined to the east side of the center, away from where strong upper-level winds of 15 – 20 knots out of the northwest were shearing the storm. Maria no longer has an eye or an eyewall, and its weak outer spiral bands on the west side were bringing rain showers to the Outer Banks, as seen on regional radar.
|Figure 1. GOES-16 view of large Hurricane Maria (left) and small Hurricane Lee (right) at 10:45 am EDT Wednesday, September 27, 2017. Image credit: NOAA/RAMMB. GOES-16 imagery is considered preliminary and non-operational.
Forecast for Maria
Maria will continue to move over the cool waters churned up last week by Hurricane Jose, and is expected to continue experiencing moderate wind shear over the next few days. Our top intensity models predict that a slow weakening of Maria will result. All of our top models predict that Maria has made its closest approach to North Carolina, and will turn to the east-northeast by Thursday, as a trough of low pressure passing to the north pulls the storm out to sea. By Saturday, Maria will lose its tropical characteristics as it speeds towards Europe, and the extratropical remnants of Maria will likely bring tropical storm-force winds of 39+ mph to portions of the British Isles on Sunday.
|Figure 2. Enhanced infrared image of Hurricane Lee at 10:45 am EDT Wednesday, September 27, 2017. Cirrus outflow from Hurricane Maria can be seen at far left. Image credit: NOAA/NESDIS.
Lee joins the majors
After nudging ever closer to Category 3 strength for almost a day, Hurricane Lee finally made the cut on Wednesday morning. Lee’s top sustained winds were 115 mph at 11 am EDT, making it a low-end Cat 3 storm. Lee is this year’s fifth major hurricane in the Atlantic, after Harvey, Irma, Jose, and Maria. Those four predecessors all hit Category 4 or 5 strength, and all of them but Jose proved to be devastating, multi-billion-dollar storms. Fortunately, Lee is flexing its muscle far from land in the central North Atlantic, close to 500 miles east-southeast of Bermuda.
An overnight eyewall replacement cycle helped put Lee over the top. Lee’s original small eye, around 15 miles wide on Tuesday, was replaced by a cleared-out, 35-mile-wide eye, surrounded by a somewhat stronger core of showers and thunderstorms. Lee’s wind field has expanded as well: hurricane-force winds extended out up to 35 miles from Lee’s center, and tropical-storm-force winds extended as far as 90 miles.
Moving northwest at 7 mph, Lee had already begun a recurvature that will take the storm north and northeast at an accelerating pace later this week. It’s possible Lee will intensify a bit more between Wednesday and Thursday morning, but from that point on Lee should be weakening rapidly. Wind shear will leap from its current 10 – 15 knots to more than 30 knots by late Thursday, and Lee will be passing over progressively cooler waters, with sea-surface temperatures below the 26°C (79°F) threshold by Thursday night.
Strong upper-level flow will haul both Maria and Lee across the North Atlantic this weekend. The remnants of both hurricanes may be swept into intense midlatitude storminess affecting the British Isles and northern Europe from Sunday into Tuesday, although as the UK Met Office noted Wednesday, "there may end up being one large area of low pressure or several separate systems. So at this time, while we can say that many places will see a period of wet and windy weather later this weekend and into next week, we can’t say which areas of the UK will see the wettest or windiest weather."
Watching the waters near Florida next week for new development
One area we need to watch for development early next week is the waters surrounding Florida. A trough of low pressure over the region will be joined by a cold front that will push south over the Florida peninsula on Saturday and then stall near South Florida by Sunday. An area of low pressure capable of developing into a tropical depression could form along the front over the weekend or early next week; this development could occur on either the Gulf or Atlantic side of the Florida Peninsula.
About 30% of the 70 members of the 0Z Wednesday GFS and European model ensemble predicted development of a tropical depression in the waters surrounding Florida by early next week, and the 12Z operational run of the GFS model predicted that an area of low pressure close to tropical depression strength would form on Saturday afternoon, a few hundred miles east of the Central Florida coast. Steering currents early next week will be pushing anything that might develop westward, into the Gulf of Mexico. Wind shear is expected to be moderate to high in the Gulf early next week, which will limit any potential development there. In their 2 pm EDT Wednesday Tropical Weather Outlook, NHC gave this area 2-day and 5-day odds of development of 10% and 20%, respectivley. The next name on the Atlantic list is Nate.
Bob Henson contributed to this post.