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  • Writer's pictureBryan Norcross

Keeping an eye on the Gulf, Philippe, and Invest #91L in the Atlantic

One maybe in the Gulf and two systems to watch in the Atlantic, both with difficult forecasts.



Tropical Disturbance #1 is loosely related to the front that was associated with the precursor system to Tropical Storm Ophelia combined with a sharp dip in the jet stream. The disturbance, such that it is, is broad and ill-defined, with hostile upper winds spreading the thunderstorms out.


Today or tomorrow, the system is expected to move under the jet-stream dip as it tracks to the west over or near the tip of Mexico's Yucatán Peninsula. The hostile upper winds should let up at that time, giving the system a slight chance to develop, assuming it's over the Gulf waters. But even if all that comes together, by late tomorrow, the atmospheric environment over the Gulf of Mexico is forecast to become too hostile for the system to maintain itself, and it would likely dissipate.


The National Hurricane Center only gives it a very slight chance of getting organized into a depression over the next day or two. There is no apparent threat to land beyond the gusty thunderstorms that will likely affect the northern Yucatán.



Midway between the northeastern Caribbean islands and Africa, Tropical Storm Philippe is steadily heading west in the general direction of the islands. The ocean is very warm, and the atmosphere is moist, but the upper-level winds are currently fairly hostile, so Philippe is not forecast to strengthen very much in the short term.


The National Hurricane Center's forecast and the consensus of the long-range computer models turn Philippe to the north well before it gets to the Caribbean. There are imaginable scenarios that would allow the system to make a more gradual turn coming uncomfortably close to the islands. Nothing would happen quickly, but in a few days, we'll have to be sure it makes the turn as forecast.


The storm's path appears to be related to how strong it gets. A weaker storm is more likely to track farther south. So the current indications are that Philippe would not be very strong if it did affect the northeast Caribbean. Since the future strength depends on the degree to which the slightly hostile atmospheric environment counteracts the extra-warm ocean, the track has more uncertainty than normal.



Behind Philippe, Tropical Disturbance #2 – officially tagged Invest #91L – is likely to develop into at least a tropical depression in the next several days. Initially, the system should lift to the north, but it's starting farther south than Philippe did. A parade of strong jet-stream dips will move across the central part of the Atlantic. The dips tend to pull well-developed systems north, but weaker storms often just get a little tug as the dips pass by.


The bottom line is… the long-range computer forecasts for this system are all over the place as they are with Philippe. The tracks range from uncomfortably close to the islands to far out to sea. On average, forecasts for undeveloped systems have higher uncertainty, so there are no conclusions to reach yet. In any case, the steering flow is relatively weak so nothing will happen fast.


We're getting close to the end of the Cabo Verde part of the hurricane season when we watch the eastern Atlantic for systems that came off Africa. Until the end of the season, we'll keep a closer eye on the western Caribbean and the Gulf of Mexico.

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