Weather Nerd

Good news: Edouard's strengthening stalls

Alleviating my fear of continuous intensification until landfall, Tropical Storm Edouard stopped strengthening overnight, and in fact weakened a bit in the wee hours of the morning. The 5:00 AM EDT discussion explains that northerly wind shear pushed the storm’s convection well to the south, completely exposing the low-level center of circulation. The barometric pressure increased to 1006 millibars at around 2:00 AM, and “it was dubious as to whether Edouard was still a tropical storm.”

In the hours since then, Edouard has re-organized and re-strengthened somewhat, and the pressure is back down to 1002 mb. Maximum sustained winds are still listed at 50 mph. But the storm has lost 12 precious hours of time in which it could have been intensifying, and now landfall in Texas is a mere 24 hours away. Also, Edouard’s forward speed has increased. All in all, he’s starting to run out of water.

As a result, it now appears less likely than it did yesterday evening that Edouard will make landfall as a hurricane, and far less likely that he’ll do so as anything more than a low-end Category 1. Nothing can be totally ruled out yet, but I’m feeling much less worried than I did last night. The Houston Chronicle‘s Eric Berger agrees: “last night’s weakening [means] that the chances of anything stronger than a category 1 hurricane are now very, very low.”

That said, some intensification is still expected. Indeed, Hurricane Watches are up along the Texas and Louisiana coastlines, indicating that hurricane conditions are “possible.” And they definitely are. Dr. Jeff Masters, who took time off from a friend’s wedding reception to post an Edouard update, wrote at 2:00 AM EDT:

The shear is forecast to decrease to near zero by Monday night, and sea surface temperatures will increase by about 0.5°C. The depth of the warm waters get shallower, with the Tropical Cyclone Heat Potential decreasing to about 20 kJ/cm^2 Monday night. Taken together, these factors should allow Edouard to intensify, although it may take 24 hours or so for the storm to organize an eyewall, as occurred with Dolly. The latest 00Z (8pm EDT) GFDL and SHIPS intensity models both bring Edouard to a borderline tropical storm/Category 1 hurricane by landfall, with the strongest winds occurring near the Texas/Louisiana border. The 00Z HWRF model, though, predicts that Edouard will not get its act together at all, and will be a tropical depression at landfall. The latest GFS model is also not very enthusiastic about Edouard.

My best guess is that Edouard will be a tropical storm with 60-70 mph winds when it comes ashore Tuesday morning. It would be a big surprise if the storm made it to Category 2 strength, since it has a limited time before it comes ashore, and is so poorly organized at present. Heavy rain is the main damage threat from Edouard.

UPDATE: Berger looks at what Houston can expect:

Assuming that the storm continues moving westward at about 9 mph — and that’s truly an assumption — Galveston should begin feeling tropical storm force winds at about 4 a.m. tomorrow, and if the storm becomes a hurricane, higher winds would come shortly thereafter.

Houston would feel the winds a wee bit later.

There could be some rainfall today not associated with Edouard, but otherwise it will be hot. Computer models such as the GFDL suggest the tropical storm’s rain won’t get here until at least shortly after midnight.


One could lose a lot of money betting on tropical storm rain forecasts. The good news for those concerned about inland flooding — which would be just about everyone in Harris County — is that Edouard is presently forecast to accelerate forward once inland.

That means we’ll get some rainfall, and there will definitely be intense downpours. But the rains should keep moving and clear the area by Wednesday morning or afternoon. … If this forecast holds, Edouard will prove a boon to Texas’ drought without causing major flooding damage. However, the computer models often don’t reflect isolated rainfall totals, which in some areas could reach up to 8 inches. So let us hope the forecast holds, keeping in mind that tropical storms often do cause major damage in Houston.

For more on Houston’s effects you can check out the Houston/Galveston office of the National Weather Service’s multimedia briefing.

The bottom line is that southeast Texas will begin tangling with the tropics during the next 24 hours, and it’s possible something as strong as a category 1 hurricane could come ashore. It’s best to prepare today for such an eventuality.

I’ll post another update on Edouard this afternoon. Berger, meanwhile, will be updating throughout the day.

P.S. In a comment on my previous post, Ubu Roi of Houblog writes:

Around here, we don’t run from a minimal hurricane, unless we’re right on the coast or in a very low area. … Minimal hurricanes are mildly dangerous, moreso if they drop lots of rain — but I’ve driven to work in the middle of one, in a dinky Chevette (which will date about when it happened, heh).

I generally agree with those sentiments. Even “minimal” hurricanes can do significant damage, as South Florida learned during Katrina’s initial landfall in 2005, but generally, if you live in a well-constructed home, not immediately on the coastline, and not in a flood plain, there’s no reason to greatly fear such a storm. So, to the extent that anyone reads my blogging as an attempt to hype Category 1 hurricanes into monster storms, they’re misreading me.

The most dangerous thing about “minimal” hurricanes, particularly when they’re over bathtub-like water in places such as the Gulf of Mexico, is that they can quickly get stronger. That is the reason I might sometimes sound “alarmist” in talking about Category 1 hurricanes: not because I’m under the misapprehension that 75 mph winds and 4-5 foot storm surges are going to cause devastating damage along wide swaths of land, but because I’m all too aware that rapid intensification can catch even forecasters off guard — never mind the general public — and if a “minimal” hurricane intensifies into a monster at the very last minute, there’s little you can do except pray. Hence the mantra: be prepared for the worst!

A rapid-intensification scenario appears mercifully unlikely in this instance, but that’s where I’m coming from when I get worried about this type of storm.