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August 2013

Tropical Development Possible Next Week in the NW Caribbean or Gulf of Mexico

   Posted by Levi at 1:22am on August 9, 2013

There are currently no significant tropical disturbances in the Atlantic, but one is likely to form in the western Caribbean next week, and will have a good shot at developing into a tropical cyclone. The originating feature is a broad, deep-layer wave of low pressure located east of the lesser Antilles, most pronounced at the 500mb level in 18z GFS analysis. This is the system I mentioned in my video on Sunday as a potential threat next week. Although there are currently few clouds associated with this feature, that should change in a few days. The wave will move westward through the Caribbean, and once west of 75-80W, it will serve as a brake on the trade wind flow coming in behind it from the east. This will cause air to pile up and rise in the western Caribbean, and widespread thunderstorms will likely result. This will likely happen in 5-7 days, resulting in at least a weak area of low pressure in the western Caribbean.

As the low moves northwestward, it will be moving into a progressively more favorable environment as ridging balloons aloft over the NW Caribbean and an upper low backs away to the west, illustrated by the GFS Day 7 upper wind forecast. The WNW to ESE orientation of the jet stream to the north over the U.S. will likely allow upper ridging to continue ballooning into the Gulf of Mexico over the disturbance, an environment conducive for tropical development. None of the main global models show significant development of this disturbance, but given the favorable environment it will be moving into, I think it will be a threat to develop in the vicinity of the NE Yucatan Peninsula. The latest runs of the GFS have begun hinting at a tropical storm forming in the Gulf of Mexico, beginning to support this idea. The GFS and CMC ensemble means have also recently begun to show an increasingly wet NW Caribbean in about a week from now, indicating heavy precipitation associated with a strong tropical disturbance.

If a tropical storm does form in the NW Caribbean or southern Gulf of Mexico, its future track will be of obvious interest. The pattern a week from now is forecasted to feature a washed out (stalled) front draped over the southern U.S., evident as deeper blues in this forecast image. The upper trough that brought this front in is likely to stall near the eastern seaboard and leave a weakness over the eastern gulf through which our disturbance could move on a northeastward path towards Florida. However, given the washed out nature of the front with high pressure building behind it, it may be difficult for a disturbance near the Yucatan Peninsula to recurve into Florida. Also, the 500mb pattern for storms near the Yucatan Peninsula that end up hitting east of the Mississippi typically features a strong trough coming down from the Midwest, not a trough that is in the process of leaving the SE US like what is forecasted for next week. Thus, a more likely path to me currently seems to be westward or northwestward into the western Gulf of Mexico towards northern Mexico or southern Texas. However, considerable uncertainty exists, as this forecast is for at least a week from today, and the track of the disturbance may be influenced by whether it even develops into a storm or not. Details about the future of this system in the Gulf of Mexico will be better known in 5-7 days when it is trying to develop in the western Caribbean.

The concept chart below illustrates my overall thoughts for this system next week. I will likely post a video update in a couple of days, especially if the computer models begin to support development of this system.




  • Udgit Mehta says:

    Great Discussion Levi- Thanks for the update- What do you think about revision of NOAA Forecast

    • Levi says:

      They still call for an active season, as I am. It makes sense given the conditions being observed.

  • Deb says:

    Should it develop, upper Tx coast and Sw La could use rain, what chance for further N movement? You may have answered but I didn’t get it. Thanks.

    • Levi says:

      As I mentioned, a northward path is one of two options, but the less likely of the two in my opinion right now.

  • mo says:

    Levi: Someone from myfoxhurricane from the Tampa Bay area linked some info to your blog from one of their discussion forums. I clicked on the link and found your site. Amazing! I am a weather buff and have always wanted a comprehensive analysis of tropical phenomenon. Your site does the trick. I have saved this site as a favorite and will come back to it often. Our local weather people are hinting at increased rain here in Tampa late next week. I am sure it is due to what you were saying. It will be interesting to see how this plays out. Thanks for the great analysis and asking questions I often ask myself. Awesome.

  • Andrew says:

    With the stalled front sagging like that, such a storm would send lots of moisture up the boundary into Florida but the storm itself would go west or northwest.

  • Dave P. says:

    500mb of the gfs shows this system next weekend in B.O.C. or southern gulf,then seems to stall do to a short wave.Yes or no?

  • Ronjon says:

    Nice summary Levi. GFS operation model has vorticity and a weak low with this feature moving into the BOC for several runs now. Latest NAVGEM, however, shifted east toward the central Gulf Coast. The Euro progs a cutoff low and trough digging down toward the GOM in 7 days. Not sure if this will be enough of a trough to pick the system up though.

  • Andrew says:

    The models Ronjon pointed out have one thing in common. Nothing is moving east into the Atlantic which was what Levi discussed in his previous post. Sometimes cutoff lows moving south into the Gulf can develop too.

  • Joey says:

    Thanks as always Levi for the very informative and able to understand discussion on the tropics. Keep up the good work.


  • Dave P. says:

    To Z or not to Z,that is the question.Hope your right about the CMC latching on the anything and everything.Looks like the 00 z run is not good for New Orleans.

  • Mitchell says:

    We’re all going to die! Seriously! Expecting the storm to impact the East Coast this year will be named Nestor and will be a Category 2 or 3 Hurricane on landfall. That’s what I feel like they are trying to tell us. Every tropical wave that forms off of the coast now becomes breaking and major news. Especially on the Weather Channel. “ALERT: Tropical Wave could hit the United States!” I seriously think the new Global Warming regime will be the end of our favorite cities and states such as New York, Boston, Fairfield, Bridgeport, New Jersey. We need to invent something that will stop Global Warming! We didn’t have the Dry air over the atlantic, we would honestly be on the N named storm by now and would likely run out of names. I have a gut feeling that every single state in the United States will be affected, including California and the west coast of the United States. This is really bad.

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