Eric Berger

Where will Irma go? The world’s best forecast models aren’t sure

Hurricane Irma remains a large, extremely powerful, and dangerous hurricane this afternoon. As one of the forecasters with the National Hurricane Center, Eric Blake noted on Twitter, “Irma has now maintained 185 mph winds for 24 hours—no Atlantic or eastern Pacific hurricane has ever stayed this strong for so long.”

Truthfully, not a whole lot has changed from this morning’s forecast, when we noted the eastern shift in some of the forecast models that kept the center of Irma east of Florida. But not the most important ones. The European and GFS models are definitely not on board with such a solution.

Before jumping into the forecast, here’s the most important message for South Florida residents with regard to Irma: A catastrophic hurricane may approach your location later on Saturday night or Sunday. The time for making final preparations is now. If an evacuation is called for your area, go. If you live in the greater Miami area, what we can confidently say from the modeling data is that there is a reasonable chance—perhaps 50 percent—that catastrophic winds are coming to one of the wealthiest, most well-developed coastlines of the country.

From the forecast perspective, the basic reality is that we aren’t much closer to understanding the ultimate track of Irma this afternoon than we were on Tuesday. If you’ve read this site for any amount of time, you know I like to use ensemble forecasting from the global models to make predictions—this is because ensembles offer a reasonable range of likely outcomes for a given weather event. And in looking at the most recent ensemble runs of the GFS and European models on Wednesday afternoon, there really hasn’t been much of a narrowing in Irma’s likely track this weekend.

First, the GFS model:

12z GFS ensemble model forecast for Hurricane Harvey. (Weather Bell)

Now there isn’t much clarity here, but the model does seem to be centered upon a track that will bring Irma into the Florida peninsula, or just east of the state. (Obviously the intensity of Irma when it reaches Florida is dependent upon the extent to which the storm traverses Cuba beforehand).

See full post

Houston cools down, and the tropics heat up

This post will provide a brief forecast for the Houston area, which really has no weather concerns at all over the next week or 10 days, and then discuss the tropics, where two other storms have developed in addition to Hurricane Irma. With 185-mph winds, Irma continues to pose a grave threat to the Caribbean Islands and southeastern United States—but the forecast is a smidgen brighter for Florida this morning.

The tropics at around 6am CT Wednesday. They are … active. (NOAA)

Houston

Some isolated showers popped up earlier this morning ahead of the cool front, and a few more may develop later this morning and early afternoon as the front moves through the metro area. Nothing to be concerned about. After this we can expect amazing weather through at least Sunday or Monday—with mostly sunny skies, highs in the 80s and lows in the 60s. High temperatures may finally get back up toward 90 degrees by the middle or end of next week, but rain chances will remain near zero.

Irma

The storm’s central pressure has continued to fall this morning (another measurement of intensity) but its winds have held steady at 185mph as it approaches Puerto Rico. The eye of Irma should pass just to the north of the island today. Here’s a look at the official forecast released by the National Hurricane Center at 4am CT:

(National Hurricane Center)

Clearly, this is a devastating forecast for Florida, essentially bringing the storm’s very worst winds and surge to an area from Miami to West Palm Beach. The storm would then continue up Florida’s spine, continuing to deliver punishing winds and waves to the eastern half of the state. However, it is equally important to note that we are discussing a forecast for conditions five days from now. Although hurricane forecasters are pretty good with forecast tracks, the average five-day error is still about 200 to 250 miles in terms of track.

See full post

Three scenarios for Hurricane Irma and the United States

If you’re only interested in Houston weather, you can skip this post. We are not going to see much rain over the next 10 days, and temperatures will generally be pleasantly cool for early September. However, we’ve had a lot of requests from readers to continue coverage of Hurricane Irma, due to the significant threat it presents to the United States. (Already, with winds of 185-mph, the storm is the second-strongest in the Atlantic basin on record). So that’s what we will provide here.

Having looked at the forecast model guidance that has come out during the last two hours, the we can have pretty high confidence in the hurricane’s track through about Friday, when it will be in the vicinity of Turks and Caicos (a beautiful area, which I hope survives this storm). After that I want to highlight three possible scenarios, neither of which I have particularly high confidence in as so many unanswered questions remain: When does Irma find the western periphery of the Atlantic high pressure system and turn north? Does it turn northwest, due north, or northeast? And how much does the storm’s center interact with Cuba? All of these questions will have profound effects.

See full post

Cold front coming, and Hurricane Irma reaches Cat. 5 status

A cold front remains on track to reach Houston on Wednesday, arriving a couple of weeks early to the region, and bringing some genuinely fall-like weather to the upper Texas coast. I’ll also discuss Hurricane Irma, because the storm has reached Category 5 status and almost certainly will have some devastating effects in the United States. We remain pretty confident the storm won’t have major effects for Texas, however.

Tuesday

We’ll still be pretty warm today, with highs in the low 90s across Houston, but for early September this is still decent weather. Houston could see some scattered showers later this afternoon, but for the most part we should be rain-free.

Wednesday

Cold front day! It’s almost like a holiday here in Houston. Moisture levels will increase a bit before the front moves through on Wednesday, most likely during the late morning or early afternoon hours. Some scattered showers are possible with the front—a few isolated areas could see as much as half an inch of rain—but for the most part this should be a breezy passage rather than one with thunder and lightning. Humidity should fall off a cliff after the front moves through, making for a pleasant evening.

Forecast map showing dewpoint temperatures on Wednesday morning. The front is almost to Houston. (Weather Bell)

Thursday through Sunday

We’ll have some great September weather after the front comes through, with highs generally in the mid- to upper-80s, overnight lows in the 60s (perhaps upper 50s for some inland areas and closer to 70 degrees along the coast). The drier air and full sunshine will feel fine.

See full post