Category: Tropical weather

We’ve had a number of really, really nice spring days in recent weeks. And expect us to get another one today. Let’s get to it.

Colorado State Hurricane Outlook

First, I want to just touch on a report released yesterday from the tropical weather research group at Colorado State University. The CSU team produces one of the most widely used and anticipated seasonal hurricane outlooks for the Atlantic. Their forecast for this year calls for below normal activity in the Atlantic basin.

They’re going with 11 storms, four hurricanes, and two major hurricanes for the 2017 season. Recall that last year saw 15 named storms, seven hurricanes, and four major (Category 3 or stronger) hurricanes. Last year’s CSU April forecast called for 12/5/2 in that order. This year will be challenging with risks of another El Nino developing and some uncertainty as to what the ocean temperature profiles in the Atlantic Ocean will look like during the peak of the season. We’ve been in an active period of Atlantic hurricanes since 1995, and there are questions as to how much longer that will last. They will monitor these variables and update their forecast in early June.

Klotzbach’s team also helps put together landfall probabilities by county. You can examine the details yourself, but in the interest of ease, they give a 3.7% probability of one or more named storms making landfall in Galveston County, compared to a 4.3% chance historically in any given year. Texas as a whole has a 38.2% chance using their methodology, compared to a climatological average of 43.3% that a named storm will make landfall. In a nutshell: Slightly lower than normal odds for a landfall than in an average season.

Use hurricane outlooks with caution

There’s a BIG caveat here. Remember, seasonal hurricane outlooks are primarily an academic exercise. Operationally and for most of you, they don’t matter. If we have two storms in the Atlantic all season and one is category 4 that plows into Galveston, it was a below normal season but an awfully bad one for a lot of people. They’ve become a curiosity we need to share, and the group at Colorado State does really good and ultimately important research. But you should ignore this forecast and go ahead and think about preparing for hurricane season anyway. 

(Space City Weather is sponsored this month by The Mole, a Jonathon Price novel.) Read More…

President Obama recently signed the Water Infrastructure Improvements for the National Act (WIIN) into law. Like many major spending acts, there’s a lot of “stuff” in this bill. It includes funding to help Flint, Michigan recover from its lead crisis, help for water projects in California, as well as re-authorization of several big conservation and restoration acts.

For those of us in Southeast Texas, there was one potentially important item in the bill. It includes a provision to speed up feasibility studies for a coastal storm surge protection system for Galveston Bay and the Houston area. This is what is more commonly known as the “Ike Dike.” The provision was added by Senator John Cornyn.

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Long time readers of mine will be familiar with the date of Sept. 24th, the point at which the historical chance of a hurricane striking Texas falls very nearly to zero. Just three hurricanes have struck Texas after that date in the last 160 years, the most recent being Hurricane Jerry, in 1989. (The storm’s landfall, on Oct. 16, is the latest a hurricane has ever hit Texas. It had 85-mph winds and came ashore along Galveston Island).

I’ve waited a few days later this year to make an “end of season” post because I wanted to follow the evolution of Hurricane Matthew (which now, clearly, will not come into the Gulf of Mexico), and because the upper-atmosphere pattern still has a September feel about it. What I mean by this is that the fast-flowing jet stream in the upper levels of the atmosphere really hasn’t dug that far south yet, bringing with it strong wind currents that are hostile to hurricane formation and intensification.

This GFS model forecast for upper-level winds next Thursday morning shows that the jet stream isn't far enough south to provide really strong upper-level winds along the Texas coast. (Weather Bell)

This GFS model forecast for upper-level winds next Thursday morning shows that the jet stream isn’t far enough south to provide really strong upper-level winds along the Texas coast. (Weather Bell)

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When tropical systems get going, the internet can be a noisy place. So Eric and I thought it would be a good idea to give everyone a user’s guide to the next tropical system that you’ll be hearing about.

What is it?

Invest 97L is the current classification of the tropical wave on the way to the Caribbean. Satellite imagery from late this afternoon shows Invest 97L approaching the Leeward and Windward Islands.

Invest 97L is rotating toward the Caribbean islands this evening. (NOAA/NHC)

Invest 97L is rotating toward the Caribbean islands this evening. (NOAA/NHC)

 

“Invests” are the classification given by the National Hurricane Center to tropical disturbances that may develop into organized depressions, storms, or future hurricanes. There are numerous “invests” each hurricane season, and the cycle runs from 90 to 99 and then repeats. Basically, it’s a nice way to keep disturbances orderly in their computer systems for tracking and monitoring purposes.

The National Hurricane Center sent out reconnaissance aircraft today and were unable to find a center of circulation at the surface, so they’ve held off on classifying this as a tropical depression or tropical storm (which will be named Matthew, assuming it gets there).  Read More…

After what seems like months of build-up, speculation and watching, Tropical Storm Hermine has finally formed in the Gulf of Mexico. The system still looks somewhat ragged, but its wind speeds have come up, and there’s now the potential for further development before it nears the Florida coast in about 36 hours.

The system has gotten a lot of hype for a mere tropical storm. Part of this is because about a week ago the respected European model really showed strong development (which hasn’t occurred yet), and the fact that it has been nearly three years since a hurricane formed or passed through the Gulf of Mexico. And while this system, formerly known as Invest 99L and Tropical Depression Nine, has been subject to some derision it now should be taken seriously—not only by Florida but much of the east US coast.

Right now this is a big tropical storm, with tropical-storm force winds out to about 100 miles from its center. Those winds may well intensify as the storm has the potential to strengthen into a Category 1 hurricane before landfall, although this is far from certain. Hermine also is both a rain (10-15 inches for some locations of Florida is possible) and surge threat to the west coast of Florida. The National Hurricane Center has these threats covered in its rainfall and storm surge products.

Track models for Tropical Storm Hermine. (Weather Bell)

Track models for Tropical Storm Hermine. (Weather Bell)

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