Sunday, June 27, 2010

Tropical Storm Alex: June 27, Update A

I made the mistake of watching some US tv news about tropical storms. Oh dear. "Tropical Storm Alex MAY be weakening over land"? OF COURSE it's weakening! Sigh. Why do they have to be so unecessarily alarmist? Doesn't everyone have enough to worry about? (rhetorical questions, no need to reply! :-)). Time for a calming cup of tea!

TS Alex made landfall yesterday in Belize, between 7 and 8pm (CDT) with winds near 65mph (TS range: 39-73 mph). A fairly strong Tropical Storm. He is now moving across the Yucatan Peninsula in a WNW direction at 10mph, and will re-emerge into the south-western Gulf later today. Currently he is centered at around 18.4N, 89.9W over Mexico, with maximum sustained wind speeds of 40mph... which means that he may not actually be Tropical Storm anymore as the demarkation is 39mph. I expect he will be downgraded to a Tropical Depression in the next update, as also previously forecast by the NHC. Despite the low wind speed, he still has very good circulation (vorticity) in the entire troposphere which is a little troublesome.

Now, the question is what will happen when he emerges into the Gulf of Mexico. The track takes him WNW towards Mexico. I agree with a Mexico landfall, but maybe not so far north as the current center of cone of uncertainty suggests. There's a chance he'll stay south (also within the cone). But that's a few days away, so things could change.

And the intensity in the Gulf? Here we have a battle between the ocean and atmosphere. How fun! :-) Atmospheric conditions are primed for strengthening of a storm (weak wind shear, strong circulation/vorticity). The forecast makes him a Tropical Storm again overnight tonight (1AM Monday), and a Hurricane tomorrow night (by 1AM Tuesday), with the possibility of a Cat 2 or 3 by Thursday - a fairly rapid intensification. However, ocean conditions are not really primed for a big storm... although the surface water temperature is warm at 30 deg C, the warm water is very shallow - waters warmer than 26.5 deg C don't extend much below 25 - 50m (because it is going over the shallow Bay of Campeche shelf - like the West Florida Shelf). My assessment is that it will intensify back to a Tropical Storm and there is a possibility that it will become a hurricane, but maybe not as rapidly as the current forecast suggests. I think it unlikely that he will be a Cat 3 before he makes landfall.

I'll try and check in later, once he's over water. I don't have much time and won't be in front of a computer for most of Monday/Tuesday (because life gets in the way at the most inconvenient moments! ;-)). Luckily Alex is pretty well behaved, and unless you are in Mexico or southern Texas, no need to overly worry about this one.

Must run! Ciao for now,

p.s. Oil & Storms:

There are a number places out there with information about oil spill and tropical storms that you should check out if you haven't already (e.g. NOAA's fact sheet: Thanks to all who sent in websites - you guys are great! :-) I'll continue to answer questions because I was asked for my wonderfully humble, scientific and humourous opinion (after people had read what's out there). (Yes, I'm still *quite* modest). ;-)

Also, thanks to J.D. (and someone else, whose email I've misplaced - sorry!) for sending me 'information' on the "Worst Case Scenario": ;-). I'm sure the movie will be out next summer!

Blog archives at

These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know.

No comments: