GeoColor satellite image of Hurricane Delta at 11:40 a.m. EDT Thursday, October 8. (Image credit: RAMMB/CIRA/Colorado State University)

Hurricane Delta was intensifying over the warm waters of the Gulf of Mexico early Thursday afternoon. It is expected to turn north on Thursday night and make landfall in western Louisiana on Friday afternoon or evening as a category 2 hurricane. A hurricane warning and storm surge warning are in effect from High Island, Texas, to Morgan City, Louisiana, with the storm surge warning extending to Ocean Springs, Mississippi.

On Wednesday night, Delta moved over Scorpion Island, a Mexican national park off the north coast of the Yucatan Peninsula. The island reported sustained winds of 65 mph, gusting to 90 mph, before the station stopped transmitting data at 7 p.m. EDT.

Hurricane hunter aircraft from both NOAA and the Air Force were in Delta on Thursday morning, and reported that the hurricane was steadily intensifying. The central pressure dropped from 973 mb at 2 a.m. EDT to 968 mb at 11 a.m. EDT, and the surface winds increased from 100 to 105 mph. They reported that the large eye of Delta was 40 miles in diameter, and open on the south side. This gap in its eyewall was allowing only slow intensification to occur.

Air Force hurricane hunters based at Keesler Air Force Base in Mississippi evacuated all their planes to Texas because of the threat Delta poses to that state.

The NOAA Hurricane Hunters this season have started delivering significant real-time wave height data to the National Hurricane Center from a Ka-band Interferometric Altimeter (KaIA); the data is being posted here. On Thursday morning, a NOAA hurricane hunter aircraft measured significant wave heights (the mean wave height of the highest third of the waves) of up to 30 feet inside Delta.

Figure 1. Damage in Cancun, Mexico, on October 7, 2020, after the landfall of Hurricane Delta. (Image credit: Protección Civil Seguridad, Mexico)

Modest damage and no deaths in Mexico from Delta’s landfall

Hurricane Delta made landfall at 6:30 a.m. EDT Wednesday, October 7, near Puerto Morelos, Mexico – 20 miles south of Cancun – as a category 2 storm with 110 mph winds. Delta caused widespread tree damage, power outages, and street flooding in Cancun and the surrounding area. As of Wednesday evening, no deaths or injuries were reported, and property damage appeared to be modest. About 32,000 tourists were relocated to shelters, according to local news site La Palabra Del Caribe.

Figure 2. Track forecasts for Delta from the Thursday morning, October 8, runs of the top computer forecast models. The closely clustered forecasts called for Delta to hit western Louisiana. (Image credit: weathermodels.com)

Track forecast for Delta

There isn’t much mystery about where Delta will make landfall, with western Louisiana squarely in the crosshairs of the storm. Steering of Delta is being controlled by a ridge of high pressure to the storm’s northeast and a trough of low pressure to its northwest.

As Delta heads northwest on Thursday toward the trough, southwesterly upper-level winds will turn the hurricane sharply to the north and then north-northeast, bringing Delta ashore over western Louisiana late Friday afternoon or early Friday evening. The computer models are tightly clustered, giving confidence in this forecast. Delta’s landfall location is likely to be within 50 miles of where devastating category 4 Hurricane Laura made landfall on August 27.

Figure 3. Predicted rainfall amounts for the seven-day period ending at 8 a.m. EDT Thursday, October 15. Delta is expected to dump 7 – 10 inches of rain in much of Louisiana, and 3 – 5 inches in portions of the mid-Atlantic. In the Pacific Northwest, a separate weather system will bring the first major rain event of the season, helping with fire-fighting efforts in Oregon and Washington. (Image credit: NOAA)

Intensity forecast for Delta

Delta has favorable conditions for intensification through Friday morning. The hurricane will be over warm, deep waters with high heat content, easily capable of sustaining intensification. Ocean temperatures at that point will decrease from 29 degrees Celsius (84°F) on Thursday to 28 degrees Celsius (82°F) on Friday morning, temperatures warm enough to support a category 3 hurricane. Wind shear is predicted to be moderate, 10 – 15 knots, and Delta will be embedded in a moist atmosphere.

Also see: Climate change is causing more rapid intensification of Atlantic hurricanes

Rapid intensification, defined by NHC as a 35-mph increase in winds in 24 hours, is a possibility: The 12Z Thursday runs of the SHIPS-RII and DTOPS rapid intensification models were giving a 12% and 20% chance, respectively, of this occurring. Delta will also expand in size before landfall, with NHC predicting over a 25% expansion in the area experiencing tropical storm-force winds. The expected increase in Delta’s size likely will lead a large section of the U.S. Gulf Coast to experience damaging storm surge at landfall, with NHC predicting a peak storm surge of between seven and eleven feet.

The live storm surge tracker at Trabus Technologies showed that Delta had not yet begun to generate a significant storm surge along the U.S. Gulf Coast early Thursday afternoon, with most tide gauges in Louisiana reporting a storm surge of 0.5 – 1.5 feet.

Figure 4. Predicted wind speed (colors) and sea level pressure (black lines) for Hurricane Delta at 5 p.m. EDT (21Z) Friday, October 9, from the 2 a.m. EDT (6Z) Thursday, October 8, run of the HWRF model. The model predicted Delta would make landfall in Louisiana as a category 2 hurricane with 105 mph winds, just 30 miles to the east of where category 4 Hurricane Laura struck on August 27. (Image credit: Tropical Tidbits)

On Friday afternoon, conditions for intensification will grow more hostile. Ocean temperatures beneath Delta at that point will be 26 degrees Celsius (79°F), the atmosphere will dry to a mid-level relative humidity of 50%, and high wind shear of 20 to 30 knots will affect the hurricane. This high wind shear may be able to inject dry air to Delta’s west into its core, significantly weakening the storm. However, a strong band of upper-level winds to the north of Delta will provide a more efficient upper-level outflow channel as the storm approaches the coast, helping counteract the increased shear. In addition, Delta will be a larger storm better able to resist high wind shear and dry air.

The top intensity models generally predicted with their Thursday morning runs that Delta would be a category 2 hurricane at the time of landfall in Louisiana. Delta will be a highly destructive storm, with significant threats from wind damage, heavy rains, and storm surge. Damages will be limited because Delta will be hitting a relatively sparsely populated portion of the coast.

Louisiana still recovering from Hurricane Laura

Hurricane Laura on August 27 roared ashore in western Louisiana as a mighty category 4 storm with 150 mph winds – the strongest landfalling hurricane in Louisiana history, and the fifth-strongest hurricane on record to make a continental U.S. landfall. Laura brought a storm surge as high as 17.2 feet above dry ground (20 feet above sea level) to Rutherford Beach, Louisiana, ranking as the ninth-highest storm surge on record for the Gulf Coast. In its wake, Laura left 33 people dead in the U.S. and over $10 billion in damage, with Lake Charles, Louisiana, suffering some of the most severe impacts.

An aerial photograph taken on Tuesday, October 6, 2020, by Erik Stratton from Moss Bluff, Louisiana (see Tweet by Lora Perkins) shows a sea of blue roof tarps as far as the eye can see, helping to put into perspective the vulnerability of the city to Hurricane Delta after the devastation wrought by Hurricane Laura. With Delta predicted to make landfall within 50 miles of where Laura did, Lake Charles is at risk that numerous debris piles from Laura heaped up by many road sides could lead to dangerous projectiles. However, Lake Charles is likely to be on the weaker (west) side of Delta’s core, and therefore should experience much lower winds than it did during Laura.

The city of Lafayette, Louisiana, on the stronger right side of Delta’s center, is likely to see much stronger winds than occurred there during Laura. Lafayette Parish, which includes the city Lafayette, has grown rapidly in recent decades. It had an estimated 250,000 people in 2019, compared with just 150,000 in 1980 and 57,000 in 1950.

Flooding on the Vermillion River that flows through the city is a significant concern. A 2020 paper by Civil Engineer Dr. Michael Waldon of the University of Louisiana, Lafayette, found “growing public awareness of the rise in both rainfall-driven and storm surge-caused flood risks within the Vermilion Watershed. These growing risks are the result of a combination of causes including land development, hydrologic changes, rising frequency of intense storms, and coastal land loss.”

What if the name Delta needs to be retired?

According to the World Meteorological Organization, if the name Delta needs to be retired from the list of hurricane names as a result of its impact on Mexico and Louisiana, it would be retired as “Delta 2020” and Delta would continue to be used when the Greek alphabet is needed again.

Bob Henson contributed to this post.

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Posted on October 8, 2020 (1:35pm EDT).

Jeff Masters

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...

60 replies on “Hurricane Delta has western Louisiana in its crosshairs”

    1. I think everyone might be burnt out.
      I know I am. I live southeast of New Orleans and taking the approach of if it comes it comes.

  1. Morning everyone….Delta has a very unique shape right now….shear is having some effects currently…..

  2. India Meteorological Department
    Tropical Disturbance Summary
    5:30 AM IST October 9 2020
    ===========================================

    The cyclonic circulation of Gulf of Thailand and neighborhood now emerged into the northern Andaman Sea. Under its influence, a low pressure area has formed.

    It is very likely to concentrate into a depression over central Bay of Bengal during the next 24 hours. It is also likely to move west northwestward and cross northern Andhra Pradesh and adjoining southern Odisha coasts as a depression during afternoon/evening of October 11th.

  3. BULLETIN
    Hurricane Delta Intermediate Advisory Number 18A
    NWS National Hurricane Center Miami FL AL262020
    100 AM CDT Fri Oct 09 2020

    …MAJOR HURRICANE DELTA HEADED TOWARD SOUTHWESTERN LOUISIANA…
    …EXPECTED TO BRING HURRICANE CONDITIONS AND A LIFE-THREATENING
    STORM SURGE TO PORTIONS OF THE NORTHERN GULF COAST LATER TODAY…

    SUMMARY OF 100 AM CDT…0600 UTC…INFORMATION
    ———————————————-
    LOCATION…26.2N 93.6W
    ABOUT 250 MI…400 KM S OF CAMERON LOUISIANA
    MAXIMUM SUSTAINED WINDS…120 MPH…195 KM/H
    PRESENT MOVEMENT…NNW OR 345 DEGREES AT 12 MPH…19 KM/H
    MINIMUM CENTRAL PRESSURE…953 MB…28.14 INCHES

  4. Japan Meteorological Agency
    Tropical Cyclone Advisory #39 – 15:00 PM JST October 9 2020
    TYPHOON CHAN-HOM (T2014)
    ==================================================
    230 km South Southeast of Cape Ashizuri (Kochi Prefecture)

    At 6:00 AM UTC, Typhoon Chan-hom (970 hPa) located at 30.8N 133.9E has 10 minute sustained winds of 70 knots with gusts of 100 knots. The cyclone is reported as moving north northeast slowly

    Storm Force Winds
    ===================
    120 nm from the center in northern quadrant
    90 nm from the center in southern quadrant

    Gale Force Winds
    ==================
    240 nm from the center in northern quadrant
    180 nm from the center in southern quadrant

    Dvorak Intensity: T4.5-

    Forecast and Intensity
    =========================
    24 HRS: 32.5N 137.1E – 60 knots (CAT 2/Severe Tropical Storm) 170 km southeast of Shionomisaki (Wakayama Prefecture)
    48 HRS: 32.3N 141.9E – 55 knots (CAT 2/Severe Tropical Storm) 220 km east southeast of Hachijo-jima (Hachijo subprefecture)
    72 HRS: 31.1N 144.7E – 40 knots (CAT 1/Tropical Storm) Sea East of Japan

  5. Japan Meteorological Agency
    Tropical Cyclone Advisory #37 – 9:00 AM JST October 9 2020
    TYPHOON CHAN-HOM (T2014)
    ==================================================
    280 km South Southeast of Cape Ashizuri (Kochi Prefecture)

    At 0:00 AM UTC, Typhoon Chan-hom (970 hPa) located at 30.3N 133.9E has 10 minute sustained winds of 70 knots with gusts of 100 knots. The cyclone is reported as moving northeast slowly

    Storm Force Winds
    ===================
    120 nm from the center in northern quadrant
    90 nm from the center in southern quadrant

    Gale Force Winds
    ==================
    240 nm from the center in northern quadrant
    210 nm from the center in southern quadrant

    Dvorak Intensity: T4.5-

    Forecast and Intensity
    =========================
    24 HRS: 32.5N 136.4E – 65 knots (CAT 3/Strong Typhoon) 120 km south southeast of Shionomisaki (Wakayama Prefecture)
    48 HRS: 33.5N 141.7E – 55 knots (CAT 2/Severe Tropical Storm) 180 km east of Hachijo-jima (Hachijo subprefecture)
    72 HRS: 33.6N 146.9E – 40 knots (CAT 1/Tropical Storm) Sea East of Japan

  6. yeah Rabbit..this storm could have been ours for sure..but not with this HIGH sitting right on top of us..whew sure is HOT but a savior none the less huh

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