Visible GOES-16 satellite image of Tropical Storm Marco (top) and Tropical Storm Laura (bottom) at 10:40 a.m. EDT Monday, August 24. (Image credit: NOAA/RAMMB)

Tropical Storm Laura brought torrential rains on Sunday and Monday to the nations of the Dominican Republic and Haiti, which share the island of Hispaniola. The highest 24-hour rainfall amount in the Dominican Republic was 11.70 inches in Barahona, on the southwest coast.

According to weather.com, at least four deaths occurred in the Dominican Republic, where one million customers lost power. In Haiti, a personal weather station in the capital of Port-au-Prince recorded 6.61 inches of rain. Floods in Haiti killed at least nine people, and another two were missing. Laura mostly spared Puerto Rico severe impacts, with 2 – 4 inches of rain falling across the southern portion of the island, but it did knock out power to approximately 100,000 customers in Puerto Rico.

Figure 1. Observed rainfall in the Dominican Republic for the 24-hour period ending 8 a.m. EDT Sunday, August 23, 2020. Rainfall in excess of four inches (101.6 mm, red colors) affected much of the southern portion of the nation. The highest rainfall amount was 11.70 inches in Barahona, in the southwest Dominican Republic. (Image credit: ONAMET)

Laura made landfall in eastern Cuba on Sunday night. At 7:51 p.m. EDT Sunday, Guantanamo Bay, Cuba recorded sustained winds of 60 mph, gusting to 72 mph. The base recorded 3.01 inches of rain from Laura through 8 a.m. EDT Monday.

On Monday morning, Laura moved off Cuba and emerged into the waters just south of the island. At 2 p.m. EDT Monday, Laura was located over the waters south of west-central Cuba, about 60 miles from the island. These waters were a very warm 30.5 degrees Celsius (87°F). Laura was headed west-northwest at 21 mph with top sustained winds of 60 mph and a central pressure of 1001 mb.

Radar from the Cayman Islands and Cuba showed that Laura did not have an inner core, and the storm’s spiral bands were not well-organized. However, satellite images late Monday morning showed a steady increase in heavy thunderstorms near Laura’s center, and the storm may be able to build a strong inner core by Monday evening.

Satellite images showed Laura had significantly expanded in size to the south of Cuba and was bringing heavy rains to Cuba, Jamaica, and the Cayman Islands. As of 2 p.m. EDT Monday, a personal weather station in Negril, Jamaica, had recorded 4.97 inches of rain. Wind gusts between 35 and 40 mph were recorded at both Kingston and Montego Bay on Monday morning. Wind gusts between 30 – 45 mph were common in central Cuba on Monday morning.

Figure 2. Radar image of Tropical Storm Laura at 10:30 a.m. EDT Monday, August 24. The storm was not well-organized, but it was bringing heavy rains to Cuba, Jamaica, and the Cayman Islands. (Image credit: Cayman Islands National Weather Service)

Laura was a very lopsided storm, with almost all of the heavy thunderstorm activity to the south of Cuba. High-level cirrus clouds were streaming out to the south, indicating good upper-level outflow on that side, but it was more restricted to the north than it had been on Sunday. Laura was embedded in a moderately dry region of the atmosphere, with a mid-level relative humidity of 60%; moderate upper-level wind shear of 10 – 15 knots was affecting the storm, driving dry air into the core and slowing development.

A track just south of Cuba, then into Gulf

Over the next four days, the Bermuda high, which is steering Laura, will be strong and will extend far to the west, forcing the storm generally to the west-northwest. The Monday morning runs of the models indicated that Laura will track just south of Cuba on Monday, with the storm crossing western Cuba and emerging into the Gulf of Mexico early Tuesday morning. If Laura is able to keep its center over water on Monday, it likely will maintain at least its current intensity, and probably strengthen by 5 – 10 mph before emerging into the Gulf of Mexico.

Figure 3. The 0Z Monday, August 24, forecast of the UKMET model, which has made the best track forecasts for Laura thus far. The model predicted a landfall in Texas to the southwest of Houston. Note that the 12Z Monday run of this model, had a landfall location near the Texas/Louisiana border, more in line with the official NHC forecast. (Image credit: weathermodels.com)

Intensification into strong hurricane likely in Gulf of Mexico

When Laura emerges into the Gulf of Mexico, conditions for intensification are expected to be very favorable. Ocean temperatures are a very warm 30 – 31 degrees Celsius (86 – 88°F) across much of the Gulf of Mexico, and an upper-level high-pressure system with light winds will bring light to moderate wind shear and excellent upper-level outflow. The atmosphere will be somewhat dry, with a mid-level relative humidity of 60%, but with that light wind shear, the dry air is unlikely to significantly impede intensification.

Tropical Storm Marco (see below) will be too small and too far away to bring increased wind shear from its upper-level outflow.

It will take a day or so for Laura to recover after its long struggle with Cuba, but immediately after leaving Cuba behind, the storm is over the warm, deep waters of the Loop Current, with its tremendous amount of ocean heat content (see yesterday’s post), leading Laura to steadily organize. This process may be slowed when Laura encounters a cool eddy in the Gulf on Tuesday afternoon, though, and in addition Laura will have to build up the entire northern portion of its circulation. Laura will expand in size on Tuesday and Wednesday, and will likely grow into a larger-than-average storm capable of generating a very large storm surge.

From Tuesday evening though landfall on Wednesday night, Laura will be passing over Gulf waters with very high heat content, and the top dynamical intensity models – the HWRF, HMON, and COAMPS – continued to predict in their 0Z and 6Z Monday runs that Laura would be at least a category 2 storm, and perhaps at category 4 strength by Wednesday evening, as it approaches landfall in Texas or western Louisiana. The 12Z Monday run of the SHIPS model gave a 24% chance that Laura would rapidly intensify by 65 mph by Wednesday morning, becoming a borderline category 3/category 4 hurricane. The official NHC forecast at 11 a.m. EDT Monday, however, called for a strong category 2 hurricane before landfall.

Figure 4. Model performance for Tropical Storm Laura for all of the forecasts made ending at 5 a.m. EDT (9Z) Monday, August 24. The UKMET model has been by far the best model, outperforming even the official NHC forecast at all times except for 12-hour forecast. (Image plotted using data from Brian Tang/SUNY Albany)

Where will Laura go?

The model solutions for Laura still have a wide spread, with much of Texas and Louisiana at risk for a potential landfall.

The model trend in recent days has been to build the Bermuda high steering Laura farther to west, pushing the storm more westward, towards Texas. This trend seems to have stabilized a bit, with the models agreeing on a landfall location between the central Texas coast and the central Louisiana coast.

The best-performing model for Laura so far has been the UKMET model, which has out-performed all other models and the official NHC forecast, except for those at 12-hour forecasts. The UKMET model’s 0Z Monday forecast predicted a landfall southwest of Houston, Texas, around 8 p.m. EDT Wednesday as an intensifying hurricane. This model was an outlier among the 0Z Monday guidance, though, and its landfall position lay outside of the NHC cone of uncertainty at 11 a.m. EDT Monday. Update: the 12Z  Monday run of UKMET model had a landfall location near the Texas/Louisiana border, more in line with the official NHC forecast.

The European model ensemble from 06Z Monday also leaned westward of the NHC cone (see below). Note that for about one-third of forecast cones, the actual track will extend outside the cone at some point. The cone is assigned a standard width each year, based on typical errors over the previous five years of tropical cyclones tracks. Some systems end up being less predictable – and some more predictable – than the cone implies. One wildcard in Laura’s future track may be the position of Tropical Storm Marco’s remnants, which may create a weakness in the ridge of high pressure steering Laura, and turn the storm more to the north over the northwest Gulf of Mexico.

Figure 5. Predicted path of Laura from the 6Z Monday, August 24 run of the European model’s 51 ensemble members (colored lines, which show minimum central pressure). The model’s operational-version track is shown as the black line. Model members showed a wide range of potential landfall locations along the coasts of Texas and Louisiana. (Image credit: weathermodels.com)

Steering currents will keep Laura moving steadily after it comes ashore, so it is unlikely to stall out and produce the type of catastrophic inland rains generated by Hurricane Harvey in 2017. Instead, storm surge and wind are most likely to be the greatest threats posed by Laura.

Residents along the Texas and Louisiana coasts should anticipate the possibility that Laura will rapidly intensify right up until landfall, potentially reaching major hurricane status.

Figure 6. Radar image of Tropical Storm Marco at 12:11 p.m. EDT Monday, August 24. (Image credit: Mark Nissenbaum/Florida State University)

Marco weakens dramatically off Louisiana coast

Tropical Storm Marco, which was briefly a Category 1 hurricane on Sunday in the southern Gulf of Mexico, no longer poses a serious threat to the U.S. coast after being ripped apart by strong wind shear on Monday.

Marco’s small size made it especially vulnerable to the destructive effects of shear and dry air. On Monday, the intense showers and thunderstorms (convection) associated with Marco were being pushed into the Florida Panhandle. Marco’s center of circulation continued to head toward the Louisiana coast, but with virtually no showers and thunderstorms around it. Bereft of the convection needed to support it, Marco’s circulation should weaken rapidly, with a downgrade to tropical depression possible as soon as Monday afternoon or evening.

As of 2 p.m. EDT Monday, Marco was centered about 40 miles southeast of the mouth of the Mississippi River. Top sustained winds were 40 mph, mainly in the convection well east of the storm, near the Florida Panhandle coast. Around Marco’s center, sustained winds were no more than 35 mph, according to surface microwave radiometer data from hurricane-hunter flights. Winds were generally 10 to 20 mph across southeast Louisiana, with gusts to 24 mph at Port Fourchon.

Marco’s weakening center is expected to arc west-northwestward near the Louisiana coast, and it is possible that Marco will not make landfall in the U.S. as a tropical storm, and instead be a tropical depression at landfall. Localized rainfall totals could end up exceeding 5″ in and near the Florida Panhandle, as Marco’s convection is channeled onshore away from the storm center. Lesser rainfall totals could push across far southern Alabama and Mississippi into southeast Louisiana by late Monday. Marco is no longer expected to generate a significant storm surge.

Figure 7. Two simultaneous storms in the Gulf of Mexico, as seen on the weather map at 8 am EDT September 4, 1933. The Great Cuba-Brownsville Hurricane of 1933, a category 3 storm with 125 mph winds, was approaching landfall in Brownsville, Texas (left) and the Treasure Coast Hurricane of 1933, with 75 mph winds (right), was over central Florida, after making landfall near West Palm Beach as a category 3. Twelve hours after this map was drawn, both storms were briefly in the Gulf of Mexico at the same time. They were 900 miles apart, which is right at the limit at where the Fujiwara effect occurs. The NOAA historical hurricane site shows that there was no Fujiwara interaction between the two storms. (Image credit: NOAA library)

Two U.S. landfalls in a three-day period: a rare occurrence

Assuming that Marco actually ends up making an official landfall, the expected landfall of Laura on Wednesday along the northwest Gulf Coast would give the U.S. two landfalls within a three-day period, a rare occurrence.

What to do if you need to evacuate during the COVID-19 pandemic

According statistics provided by Dr. Phil Klotzbach of Colorado State University, the U.S. has experienced double landfalls within three days of each other on only 12 other occasions since 1851 – an average of once every 14 years. The most recent double landfall occurred in 2004, when two pairs of double landfalls occurred. Tropical Storm Gaston hit South Carolina at 12Z Aug. 29, and Tropical Storm Hermine hit Massachusetts just 39 hours later. Earlier that same year, Hurricane Charley had hit southwest Florida just 30 hours after Tropical Storm Bonnie had made landfall in the Florida Panhandle.

The shortest time on record between two continental U.S. landfalling hurricanes is the 23 hours that separated Treasure Hurricane (9/4/1933 at 5 UTC) and Cuba-Brownsville Hurricane (9/5/1933 at 4 UTC).

Perhaps the craziest U.S. tropical cyclone onslaught occurred in 1923, when three tropical storms hit the U.S. within a four-day period, between October 16 and October 19.

Editor’s note: Posted August 24, 2020, at 2:02 p.m. EDT. This post was updated at 2:15 p.m. EDT to reflect the latest NHC advisories and the 12Z run of the UKMET model.

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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...

Bob Henson

Bob Henson is a meteorologist and journalist based in Boulder, Colorado. He has written on weather and climate for the National Center for Atmospheric Research, Weather Underground, and many freelance...

236 replies on “Laura expected to hit Gulf Coast as at least a Category 2 hurricane”

  1. I just posted about a mandatory evac order for Galveston Island and other voluntary evas near Galveston. The post is awaiting approval???
    foxtrot tango whiskey <<<<<<?

    1. Not seeing it pending.. here they are though..

      Mandatory evacuations

      Galveston — The city has issued a mandatory evacuation, instructing all residents to leave the island no later than Wednesday morning. All city of Galveston services will be suspended at 12 p.m. Read more.

      Voluntary evacuations

      • Chambers County The county has issued a voluntary evacuation for residents living in flood-prone and low-lying areas. 
      • Brazoria County —  The county has issued a Voluntary Evacuation for low-lying coastal communities outside the protection levee. All residents need to continue to watch Hurricane Laura closely, as the track for this storm continues to change.
      • Seabrook — A voluntary evacuation for residents and businesses in low-lying areas in Seabrook, specifically lower Todville from Red Bluff south to SH 146 and Baywood Drive. 
      • Nassau Bay — A voluntary evacuation has been issued for all disabled residents and those with medical needs in the area.
      • Bolivar Peninsula —  Galveston County Judge Mark Henry has issued a voluntary evacuation for residents on the Bolivar Peninsula, including the unincorporated areas of Port Bolivar, Crystal Beach, High Island, and Gilchrist

      https://www.khou.com/article/weather/list-cities-counties-that-have-issued-voluntary-evacuations-ahead-of-tropical-storm-laura/285-e9a50a96-dd0e-43f9-a91c-83e6e0b1d6da

      1. Saw they modified it pretty quick. They must of had a bunch of phone calls emals and texts!

  2. City of Galveston officials at 6 am issued a mandatory evac order for Galveston Island. FB link https://www.facebook.com/pg/GalvestonOEM/posts/

    Other voluntary evac orders near Galveston and Houston mentioned on KHOU TV this morning. https://www.khou.com/article/weather/list-cities-counties-that-have-issued-voluntary-evacuations-ahead-of-tropical-storm-laura/285-e9a50a96-dd0e-43f9-a91c-83e6e0b1d6da

    Excerpted from the Galveston Island Mandatory evac order
    “Given the uncertainty of the path and the heightened intensity of this storm, as well as the track westward overnight, the City of Galveston is issuing a mandatory evacuation for all residents. The mandatory evacuation was signed at 6 a.m. Tuesday. Galveston residents should secure loose items at their property and leave the island today. It is urgent that residents heed this mandatory evacuation and leave with all family members and pets.

    “If you are signed up for the State of Texas Emergency Assistance Registry, the state will begin staging buses at 47th and Broadway at the Island Community Center this morning. If you are in the STEAR program, but do not have a way to get to the community center, please call 409-765-3710 for assistance.”

  3. Miami and Tampa/St.Pete, Charleston, New Orleans, so far we’ve been very very fortunate in 2020 hurricane season. Laura’s about to change all that unfortunately. Steering is so Florida should expect to be hit by at least one major this season. Always be vigilant, it’s easy to become complacent due to recent hurricane history, know the full historical context. https://www.nhc.noaa.gov/gifs/1992andy.JPG

    1. It is really sad so few support me here. I’ll leave you all with a poem above. I really do wish you all the best. Thanks Jeff, thanks Bob. I find being here to be a detriment to feeling supported for obvious reasons shall we say. When the rest of the Crew gets here, we all know that heads in only one direction. So I will take my cue and say goodbye and view from afar. WWW signing out, know I go with peace in my gates and I have no ill will towards a single one of you. All the best.

  4. Good Morning!
    My sister lives in League City TX, which is near the Galveston Bay. They got 4 ft of water in their house from Hurricane Harvey. With models trended further West my fear is that they’ll take a direct hit. I’ve convinced them to evacuate. Does anyone know what they’re looking at as far as storm surge goes?

    1. Good job talking them into evacuating! League City sits fairly low, elevation-wise, so even a 3-5 foot surge can cause flooding.

      1. They’ve only lived there a year so they really have no idea what to expect. But she said the roads flood there with normal rainfalls.

        Thank you

    2. Is there a reason I can’t share the storm surge map from the old WU link? Trying to answer Alaina’s question. Just wondering if sharing anything from WU directly was going to be disallowed? No worries, just wondering.

    3. That was from rainfall. This is not a rain flooding problem, but rather a storm surge flooding problem. It depends on the elevation of their house and distance from tidal waters (Clear Lake, Clear Creek, Dickinson Bayou, Galveston Bay). Are they west of I-45? Are they on the water? Makes a big difference.

    1. a wave still over land means nothing – different mechanics for storm generation there.

      Also- who cares at this point, with a likely major hurricane 48 hours away from impacting CONUS?

  5. Uh… the trough is over central to west Texas. It isn’t moving much – just setting the edge of the high.

    And once a storm gets rocking, without shear, dry air is unlikely to impact the strength of the storm. And Laura will have a very light shear environment, and she already has a solid envelope of moisture around her. Dry air won’t mean **** to her.

  6. The Weather Channel survives via hype and ratings. An LCH landfall, per the models, is looking less likely – it is much more likely to be a Port Arthur-ish landfall, if not slightly west of that. But there isn’t enough ratings on that, because only with LCH and slightly east can you draw in the New Orleans market and bring up all the Katrina hype. Never mind that Rita (2005) basically went straight up the Sabine River.

    At least TWC isn’t being stupid, and hyping up a Houston/Galveston landfall. That would create a Rita evacuation 2.0 situation – which could kill thousands when combined with our latent pandemic situation here in the Houston metro area.

  7. What are the real chances this thing will RI right b4 landfall and be a Cat 5? Worst case scenario.

    1. It is VERY difficult for a storm to RI right by landfall. And unlikely. It isn’t impossible – but it is rather unlikely.

      That said, please don’t wish for that – it would massively upgrade the death toll and damage numbers. (and I don’t want to be forced to go in to work during a storm)

    2. Levi’s vid last night mentioned how the shear will drop to neutral/zero just before landfall. The shear won’t be that much of a problem for Laura to begin with, but you can definitely anticipate strengthening up through landfall.

    3. NHC is forecasting shear increasing in the last 12 hours before landfall, so not likely. Timing-wise, there’s a good chance it will have just completed an erc if it ri’s in the middle of the Gulf too, so again, not likely

      1. To clarify, yes the shear increases, but from an opposite direction. It’s that switch in direction of the shear just before landfall that reduces it to neutral/zero. The subsequent increased shear won’t have enough time (<12 hours) to affect an already forecast major storm.

  8. Me: Why are you doing this to me Laura?!
    Laura: I’m not doing anything strange, the Atmosphere and warm SSTs provide what it need to be a Monster.
    Me: what I should do then?
    Laura: Leave this place! You don’t see that I’m giving you time, you don’t see slown down!
    Me: Alright then.
    Laura: You better! When me reach, I’m not going to be pretty.

  9. Japan Meteorological Agency
    Tropical Cyclone Advisory #33 – 21:00 PM JST August 25 2020
    TYPHOON BAVI (T2008)
    =================================================
    East China Sea

    At 12:00 PM UTC, Typhoon Bavi (955 hPa) located at 30.6N 125.2E has 10 minute sustained winds of 80 knots with gusts of 115 knots. The cyclone is reported as moving north northwest at 6 knots.

    Storm Force Winds
    ====================
    90 nm from the center

    Gale Force Winds
    =================
    150 nm from the center in eastern quadrant
    120 nm from the center in western quadrant

    Dvorak Intensity: T5.0

    Forecast and Intensity
    =======================
    24 HRS: 34.7N 124.7E – 85 knots (CAT 4/Very Strong Typhoon) Yellow Sea
    48 HRS: 44.4N 125.8E – Extratropical Low overland northeastern China

  10. Morning everyone…..first light today on Laura…..you can already see large cloud tops popping up close to the center…..she will do nothing but strengthen over the next 36+ hours….a major hurricane will likely hit the US this week….

  11. Good Morning YCC. If you have any relatives/friends that live right on the coast or barrier islands in the cone for Laura, call them, check on them, and encourage them to evacuate if they are thinking of ignoring a local evac order and staying for the storm. It is too risky and “life threatening” as always noted by NHC and local authorities.

    My Daughter graduated Yale………..Go Trumbull College.

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