Weather Spectrum

It is beginning to look like someone flipped the hurricane switch to the "ON" position. Currently there are three areas that the National Hurricane Center is watching. The first, Tropical Storm Ernesto, the second is an area of disturbed weather near the southern tip of Florida and Bahamas, and the third is so far out right now that even though it could become a depression or tropical storm in the next 48 hours it looks like it is at a high enough latitude to turn northward before reaching the Windward Islands.
Here is a map of the two disturbances and Ernesto...



 

Area 2 (by Florida): This is a surface trough of low pressure that is generating scattered showers and thunderstorms, but has become a bit more congealed over the last 48 hours. Upper level winds are currently not very conducive for development (20 knots of southwesterly windshear) and its proximity to Florida will limit its time over water as the trough moves to the northwest at about 10 MPH. Interestingly, the model run for the system shows that it could make its way towards the central Gulf coast and possibly the upper Texas coast by Wednesday. Development, again, is not very likely, but it bears watching. At least if it comes this way we could see some rainfall.

Model run of Area 2:


The National Hurricane Center gives this system a low chance of developing in the next 48 hours. We will have to see where it goes in the next few days.

Tropical Storm Ernesto: As of 5pm EDT Ernesto is at 13.9N and 64.1W or 2,295 miles from Galveston. Movement is to the west at 21 MPH. Pressure was 29.59 inches and the maximum sustained wind was 50 MPH.

This evening Ernesto has really let off an explosion of convection at the center. This is Ernesto beginning to get better organized, and the higher ocean heat content is providing plenty of fuel for the thunderstorms. Additionally, the wind shear has relaxed a bit allowing for maybe a bit of strengthening tonight. Here is an image of Ernest over the last 3 days.

Clearly, he's getting his act together. And while there are still a couple of models that suggest Ernesto will fizzle, this image makes that situation seem more unlikely... Notice by the third image that not only is there a persistent ball of storms over the center, but it is also noticeably larger than it was only yesterday. Of course, it is over water that is about 86-88 degrees Fahrenheit. Quite warm! As the winds of Ernesto churn up that water, the water droplets are blown into the air where they evaporates and get converted to heat energy within the system once the water vapor condenses. This begins the cycle of intensification for a storm. We'll see if the convection persists overnight.

Overall, the forecast for Ernesto remains fairly complicated after 72 hours. Looking at the models...

They are very well in alignment up to 72 hours. Towards 96 hours a few models begin to take the storm in more westward or northward directions. The two outlier models to the north of the rest are not being leaned on heavily. One of them is a statistical model that does not take into account the storms intensity or environment. It only looks at history. The second is usually a fairly reliable model, but I wonder if it is picking up on that Florida system possibly weakening the ridge a bit and allowing Ernesto to turn early. While this might be the case of the Florida system and Ernesto were stronger, neither will be having much impact on the high pressure that is currently steering Ernesto westward, and quickly at that.

So the model consensus and official track keep Ernesto on a west-northwestward track through 120 hours. The ability for Ernesto's track to shift more northward or stay at the southern end of the guidance will depend on the strength (stronger storms tend to jog a bit more northward) and center reformations. The center can shift around underneath convection and jogs north or south will often cause wiggles in the track in the respective directions. Otherwise, the high pressure will dominate the steering. Questions arise after 96 hours. Will Ernesto move into the Central Gulf of Mexico, will it continue West into the Yucatan, Bay of Campeche, and/or Mexico? Right now it looks like the Yucatan and/or western Cuba will feel the effects from Ernesto as a category 1 or 2 hurricane by Tuesday, August 7th.

Here is a chart of intensity guidance...

The Official Intensity forecast (red) keeps the system a category 1 before weakening as it traverses land. I wouldn't be surprised if this is adjusted upward as Ernest gains steam moving across the Caribbean. A category 2 hurricane cannot be ruled out as the system approaches the Yucatan Peninsula.

Back to guidance and track...If the ridge steering Ernesto westward remains strong enough, it will continue steering Ernesto westward over the Yucatan, which will also weaken the system and potentially keep it moving into Mexico. If Area 2 moves towards Texas, it's possible that a weakness could develop in the ridge allowing Ernesto to tag along behind the trough. That would not be good news for Texas or possibly Louisiana. Hopefully the models will stay tight in the short range and, by Monday, we could have a better idea of the outcome. Right now, folks traveling around or residing near/on the Yucatan Peninsula, Jamaica, and Western Cuba should be watching this system carefully and making preparations to adjust/postpone trips that have you in these locations from 8/6-8/9 or preparing for a hurricane if you live in these areas. Everyone else along the Gulf coast and Mexico should be watching this system as it tracks through the Caribbean.

Here is the official 5-day track by the National Hurricane Center showing the cone of uncertainty around the forecast points widening farther out in time.

Please stay abreast of this situation. I will continue updating daily or more frequently as needed.

Have a good weekend!!