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Hurricane Delta Strengthens Into a Category 2 as it Heads For Laura-Ravaged Louisiana; Hurricane Warnings Issued

Published in 8 October, 2020

At a Glance

  • Hurricane Delta is over the Gulf of Mexico and has strengthened into a Category 2.

  • Delta is expected to landfall along the northern U.S. Gulf Coast on Friday, most likely in Louisiana.

  • Storm surge, destructive winds and flooding rain are all expected.

  • This includes areas ravaged by Hurricane Laura in late August.

Hurricane Delta has strengthened back into a Category 2 as it heads for a Friday landfall on the Gulf Coast with storm surge flooding, damaging winds and rainfall flooding from Louisiana and east Texas to Mississippi. Current Watches and Warnings A hurricane warning is in effect from east of Sabine Pass, Texas, to Morgan City, Louisiana, including Lake Charles and Lafayette in Louisiana. This means hurricane conditions are expected within 36 hours. A storm surge warning is also in effect from Sabine Pass, Texas, to Ocean Springs, Mississippi, including Calcasieu Lake, Vermilion Bay, Lake Pontchartrain, Lake Maurepas and Lake Borgne. This means a life-threatening storm surge is expected within 36 hours. Residents near the immediate coast and adjacent bays should rush preparations to completion on Thursday and follow any evacuation orders from local emergency managers.

A storm surge watch is also in effect from High Island, Texas, to Sabine Pass, Texas. This watch means a dangerous, life-threatening inundation from rising water moving inland is possible within 48 hours.

Tropical storm warnings are in effect from San Luis Pass to Sabine Pass, Texas; east of Morgan City, Louisiana, to the mouth of the Pearl River, including New Orleans, and for Lakes Pontchartrain and Maurepas. This means tropical storm-force winds are expected within the next 36 hours.

A tropical storm watch extends east of the mouth of the Pearl River to Bay St. Louis, Mississippi. This means tropical storm-force winds are possible.

Forecast Timing, Intensity
Delta has become better organized and is now a Category 2 with maximum sustained winds of 100 mph. The hurricane is moving northwestward at about 15 mph.

With a bubble of somewhat warmer Gulf of Mexico water and lower wind shear in its path, Delta is expected to continue strengthening through Thursday night.

Delta will also turn northward toward the U.S. Gulf Coast.

As it draws nearer to the Gulf Coast, Delta’s wind intensity could diminish somewhat due to increasingly unfavorable upper-level winds and cooler Gulf water.

Despite this weakening on approach, Delta is still forecast to be a formidable hurricane at landfall, most likely along the Louisiana or the extreme upper Texas coast on Friday.

Delta will then move inland over the lower Mississippi Valley this weekend as it weakens into a remnant area of low pressure.

Forecast Impacts
Storm Surge, Waves

Swells generated by Delta should begin to arrive along the Gulf Coast, from South Texas to the Florida Panhandle and even western Florida Thursday.

These swells are likely to generate dangerous rip currents at beaches and could lead to some coastal flooding at high tide in some low-lying areas Thursday, particularly in southern Louisiana.

Delta’s storm surge will be dangerous and life-threatening regardless of any weakening of its winds up until landfall.

The highest storm surge is expected in parts of south-central Louisiana, not just near the immediate Gulf Coast, but also in bays, inlets and to some degree inland along rivers and bayous. Inundation could reach 7 to 11 feet above ground in these areas.

A dangerous storm surge is also expected in areas that were ravaged by Hurricane Laura in late August. Any potential shift westward in the forecast track could bring higher storm surge to these areas.

At least some storm surge flooding is also expected in southeast Louisiana, including along Lake Pontchartrain, and along the Mississippi and Alabama coasts, including areas affected by Hurricane Sally last month.

Winds Tropical storm-force winds could arrive in the hurricane warning area along the northern Gulf Coast as soon as early Friday. Hurricane conditions are expected in this area by Friday afternoon and evening.
The strongest winds with Delta will be near the Louisiana coast at landfall as the eyewall moves ashore. This is where structural damage, power outages and downed trees will be most widespread. As with most hurricanes, strong winds capable of downing trees and power outages will also extend inland as Delta gains some forward speed near and after landfall, into much of Louisiana, extreme eastern Texas, Mississippi and southern Arkansas late Friday into Saturday.

Flooding Rainfall

A faster forward speed than what we saw with Hurricane Sally last month will lessen Delta’s extreme rainfall potential, though heavy rainfall is still expected, particularly along and to the east of its path.

This heavy rainfall combined with storm surge could worsen and prolong flooding for a time along the northern Gulf Coast.

According to the National Hurricane Center, 5 to 10 inches, with isolated 15-inch amounts are expected with Delta in southwest and south-central Louisiana. This rainfall could cause flash flooding and minor to locally moderate river flooding.

Rainfall totals of 3 to 6 inches, with isolated 10-inch amounts are forecast in parts of extreme eastern Texas, southern Arkansas and western Mississippi.

Some locally heavy rainfall will also spread into the Ohio Valley, Southeast and mid-Atlantic this weekend.

Tornadoes

As with most landfalling hurricanes and tropical storms, there’s also a threat of isolated tornadoes from Delta.

Southeast Louisiana and southern Mississippi have the greatest chance of seeing a few tornadoes Thursday night and Friday.

Storm History
Tropical Depression Twenty-Six formed late Sunday evening to the south of Jamaica and then strengthened into Tropical Storm Delta on Monday morning, the 25th named storm of the 2020 Atlantic hurricane season.

Delta became the ninth hurricane of the 2020 Atlantic hurricane season on Monday evening. Reconnaissance aircraft measured a drop in central pressure of 18 millibars from Monday’s 2 p.m. EDT National Hurricane Center pressure estimate to when it was found to have become a hurricane about six hours later. Winds in Delta increased by 85 mph in the 24 hours ending 11:20 a.m. EDT Tuesday. That was more than double the criteria for the rapid intensification of a tropical cyclone, which is a wind speed increase of at least 35 mph in 24 hours or less. Delta’s rapid intensification was due to an environment of the highest ocean heat content anywhere in the tropical Atlantic basin, low wind shear and sufficiently moist air, in a region notorious for rapid intensification in October, according to Sam Lillo, a NOAA scientist based in Boulder, Colorado. Delta’s tiny size also helped it intensify so rapidly. Delta made landfall Wednesday morning around 5:30 a.m. CDT near Puerto Morelos, Mexico, in the Yucatan Peninsula, with maximum sustained winds of 110 mph, making it a Category 2 hurricane.
A wind gust to 75 mph was measured at Puerto Morelos, 64 mph in Cozumel and 106 mph on an elevated WeatherFlow observing site near Cancún. Delta’s weakening prior to its Yucatan landfall appeared to be due to land interaction, some modest wind shear impinging on the hurricane from the east, inhibiting its outflow aloft, and also perhaps some dry air working into the tiny circulation. The maximum sustained winds in Delta topped out at 145 mph Tuesday, but were down to 85 mph as of Wednesday 4 p.m. CDT soon after emerging over the Gulf of Mexico.

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