Eric Berger

Good morning. Ida has finally weakened into a tropical storm this morning, and is now slowly, at a rate of about 8 mph, moving away from Southern Louisiana. Much of the region is submerged under storm surge and very heavy rainfall. More than 1 million customers in the state, affecting about half of the state’s population, are without power today. Some will be without power for many weeks. Ida, in short, has left a sobering trail of destruction and misery in its wake. We must help our neighbors, and here are some ways to do that right now.

Monday

Today will be hot and sunny, with only a slight chance of showers and thunderstorms. Highs will likely reach the upper 90s. As Ida pulls away from Louisiana, winds will be out of the north and northwest locally, at about 5 to 10 mph, and the overall flow will draw warm air into the region. Rain chances will be down to around 10 percent. Overnight lows will be around 80 degrees.

Tuesday

This will be a similar day to Monday, albeit with slightly higher chances of rain showers, perhaps on the order of 20 percent.

Wednesday and Thursday

Low pressure aloft will bring a modest increase to rain chances by the middle of the week, perhaps about 40 percent for areas south of Interstate 10, and less to the north, and this should also cool temperatures down into the mid-90s. Skies should otherwise be mostly sunny with warm and partly cloudy nights.

Friday, Saturday, and Sunday

While the weekend forecast is not yet locked in, the greatest likelihood is that we see hot and sunny weather, with highs in the mid-90s. As some slightly drier air mixes in, overnight lows may drop into the mid-70s. While not “nice” this definitely would be more pleasant than sultry nights around 80 degrees. Overall rain chances look low this weekend, probably below 20 percent each day.

Tropics

With Ida inland, and an inconsequential tropical depression in the open Atlantic Ocean, what else is there for us to worry ourselves about? The primary area to watch is the southern Caribbean Sea where conditions are somewhat favorable for a tropical depression to develop later this week. The National Hurricane Center gives this area a 20 percent chance of development.

This system is likely to approach Central America or the Yucatan Peninsula later this week, and if it survives interactions with land—which is far from certain—something may eventually move into the Gulf of Mexico. However there is no strong signal in the global models that this will happen, and if it does, there’s little indication it will eventually track toward the upper Texas coast. So while this is something we’re watching, it’s not something we’re particularly concerned about. As for the disturbance moving off of Africa (red X in the map above), it has a high chance of developing but is likely a fish storm that will not bother and landmasses.

Hurricane Ida has rapidly intensified overnight, seeing a steep pressure fall and maximum winds increasing to 150 mph. Very nearly a Category 5 hurricane, Ida should reach the southern coast of Louisiana, about 50 miles due south of New Orleans, around Noon today.

This will be the most devastating hurricane to hit the region since Katrina, 16 years ago today. For some areas, in some ways, it will be worse. The eyewall of the storm will pass very near to the New Orleans metro area. Hurricane-force winds extend across a 70-mile diameter.

Over the next 24 hours parts of Southeastern Louisiana will experience sustained winds well above 120 mph with higher gusts, 15 to 20 inches of rainfall, and a storm surge of 12 to 15 feet. For the New Orleans area, the winds and rainfall should be significantly greater than experienced during Katrina, although the surge should be less. This storm will offer a stiff test of the levee system built after Katrina struck the below sea-level region in 2005.

Ida will be barreling into a low-lying, swampy part of the U.S. Gulf Coast. The storm surge will move easily over this region for miles. While parts of the coast of sparsely populated, there is also major infrastructure in harm’s way. Jeff Masters and Bob Henson have an excellent rundown of damages this region experienced during Katrina, including a complete shutdown to the Port of New Orleans and weeks of delayed barge traffic. Impacts will be similarly severe this time around. Food and fuel prices should rise across the country.

There is no way to sugarcoat this situation. For those who survive, months of misery await the inhabitants of Southeastern Louisiana. Normally recovery efforts are led in Louisiana out of Baton Rouge, the state capital, which is about 100 miles inland. However, Ida is forecast to pass just east of Baton Rouge, with sustained winds of 100 mph. It seems very probable that Ida will knock out power along the entirety of the region’s most populated core, from New Orleans to Baton Rouge. The state—which has one of the worst COVID-19 outbreaks in the country, and nearly 500 patients in ventilators—will lose much of its ability to function. This is just an exceptionally grim situation.

As a forecaster there is not much else to say. The storm is here, and it is a gut punch. Ida is a nightmare scenario for the state of Louisiana. We must stand ready to help them survive, recover, and rebuild.

Hurricane Ida has strengthened significantly today, going from barely tropical storm status to a Category 1 hurricane with 80-mph sustained winds. Unfortunately, there is little to inhibit further strengthening this weekend. After Ida moves across Cuba tonight, the combination of low wind shear, a moist atmosphere, and blazing hot Gulf of Mexico sea temperatures are ideal for rapid intensification. For this reason, the latest National Hurricane Center forecast brings Ida to a Category 4 major hurricane before landfall along the central Louisiana coast on Sunday afternoon. Confidence is very high in this track.

This post will address what such a storm will actually mean for people on the ground. First up is a forecast for “wind gusts.” This is different than sustained winds, which are how forecaster define the intensity of a storm. But gusts are an appropriate measure of maximum winds. Here’s a forecast for the swath of highest gusts from Ida. It is not gospel, but it offers a good approximation of what to expect, where. There will be major structure damage and widespread power outages.

The next threat from a hurricane like Ida is storm surge. The graphic below from the National Hurricane Center is the best estimate for the combination of surge and tide above normal water levels. Ida will bring a dangerous storm surge to the Mississippi River delta area, and parts of New Orleans not behind the levee system.

The final major threat from a hurricane like Ida is inland rainfall. The storm is going to keep moving, but it will slow a little as it approaches the coast and moves inland. This should allow for some areas of southeastern Louisiana to experience 10 to 20 inches of rainfall, which will be falling on top of a significant storm surge. These are dangerous amounts of water for unprotected areas.

There is not much of a silver lining for this storm, which is set up to deliver a gut punch to the state of Louisiana. The only thing we can offer is that the western part of the state—including Lake Charles—that was pummeled during the 2020 hurricane season should escape the worst of Ida. After this storm moves away from New Orleans later on Monday and Tuesday it will be time to help. That is something the generous people of Houston are very good at.

Matt or I will have an update on Saturday before noon.

Good morning. The tropical system in the Caribbean Sea continues to show better signs of organization this morning, and will likely become a depression or Tropical Storm Ida later today or tonight. We continue to watch this system closely, and over the the last 12 to 24 hours most major models have trended east with their forecast. The most likely possibility now is that a strong hurricane comes ashore somewhere in Louisiana on Sunday or Sunday night. But we definitely cannot rule out impacts to Texas. Please find more information below.

Also, as you may recall, we launched a Spanish-language version of Space City Weather this week. At 11 a.m. CT today please join me, the editor of the new site, Maria Sotolongo, and Rolando Salinas from Reliant Energy to talk about why we’re doing this. The event will take place on our Facebook page.

Thursday

There are some scattered showers offshore this morning, and they should develop inland later this afternoon. This should yield perhaps a 30 to 40 percent chance of rain, but there will still be enough sunshine to drive temperatures into the mid-90s. Winds will be light, generally out of the east. The upper air pattern becomes more favorable for rain this evening, through the overnight hours, into Friday so there is about a 50 percent chance of showers tonight.

Friday

We expect fairly widespread showers on Friday morning, with the potential for some heavy rain to produce a quick accumulation of perhaps 2 inches for some locations. Showers should end from south to north during the late morning or early afternoon hours. Highs will likely reach about 90 degrees under partly sunny skies.

Saturday and Sunday

The overall fairly wet pattern should continue through the weekend, with partly sunny skies, highs in the low 90s, and perhaps 50 to 60 percent rain chances each day. The ultimate track of Invest 99L is going to have a lot to say about our weekend weather so any forecast now is very, very tentative.

Tropics

What we know is that Invest 99L is starting to become better organized, and should move into the Gulf of Mexico on Friday night or Saturday morning. After this time there is not much to hamper its organization—there is little dry air aloft, and wind shear is relatively low—and plenty of warm Gulf water for the system to work with. Our expectation is that the storm will become a hurricane, a possibly a major hurricane by later on Sunday as it approaches the Gulf coast.

So where will the storm go? That will depend on the extent of a high pressure ridge over the southeastern United States. Most of the model guidance now shows enough of a weakness in the ridge to allow the storm to travel more northeasterly, likely bringing it to the coast somewhere between the Texas-Louisiana border and Mississippi. Because 99L is likely to intensify fairly rapidly, this could facilitate a more northerly turn, which probably puts southeastern Louisiana under the biggest threat for now. The bottom line is that if you live in Louisiana, particularly the New Orleans area, there is a significant threat that a powerful hurricane will come to the coast in just a little more than three days from now.

As for Texas, we definitely cannot rule out direct impacts from this system. There are some scenarios in which a weaker storm cannot force its way north by influencing the ridge of high pressure. In this case the storm would turn more westerly, toward the Texas coast. There is enough uncertainty in the forecast to keep a close eye on the system. But at this point I would say we’re cautiously optimistic about the upper Texas coast, including Houston, being spared this weekend and early next week.

Matt or myself will have an update later this afternoon or evening.