Two tropical systems to move into the Gulf of Mexico early next week

Weather Blog

UPDATE: Tropical Depression 14 has been upgraded to a tropical storm and becomes Tropical Storm Marco.

Peoria, Ill. (WMBD) – The National Hurricane Center (NHC) is tracking two separate tropical cyclones that are expected to move into the Gulf of Mexico, nearly simultaneously, early next week.

Tropical Depression 14 (expected to become Tropical Storm Marco) is located in the Caribbean and is expected to move into the Gulf of Mexico Sunday and strengthen into a Hurricane by Monday afternoon south of Texas. Meanwhile Tropical Storm Laura is in the Atlantic and is approaching the Greater Antilles. Laura is expected to reach the Gulf of Mexico on Monday and strengthen in to a Hurricane on Tuesday. Whether or not both storms will be hurricanes simultaneously at any point early next week is not yet clear, but if it happens it will be the first time its happened on record.

While there has never been two hurricanes in the Gulf of Mexico simultaneously, on two separate occasions there were two tropical systems in the Gulf. The first known event was on September 4th, 1933 when a Category 3 hurricane made landfall near Brownsville, TX while a tropical storm was moving across the Florida Peninsula. The second instance of two separate storms moving through Gulf of Mexico occurred on June 18th in 1959.

Surface map from September 4th, 1933 showing one hurricane moving towards Texas while another storm moves over Florida. Courtesy: NOAA

So what could happen with two storms in the gulf?

There have never been two hurricanes in Gulf of Mexico at the same time in recorded history, and it’s not clear whether or not we’ll see that early next week, but it could be close. The exact tracks and strength of each storm remain uncertain and the rareness of having two tropical systems in the Gulf at the same time makes the forecast even more unclear but there are a few scenarios that could play out.

Fujiwhara Effect
This is a phenomenon that occurs when two separate cyclones within 900 miles of each other orbit around a center point between the two storms, gradually getting closer in the process. Sometimes this process also allows one or both storms to intensify or even merge. While the storms will be within 900 miles of each other, their proximity to land could limit their ability for the process to take effect. However, it is possible that one storm system pulls the the track further east or west with slight arch.

Fujiwhara Effect example. Typhoon Pat and Tropical Storm Ruth in 1994

One Weakens, One Strengthens
Recent models have trended towards this solution where Tropical Depression 14 weakens prior to making landfall in Texas as the system encounters wind shear from an upper level trough. Meanwhile, Tropical Storm Laura’s track has trended further south and west and keeps it over the warm waters of the Gulf for a longer period of time with minimal wind shear allowing the storm to intensify, possibly significantly) before making landfall somewhere along the Gulf Coast.

Both Storms Weaken
If Tropical Depression 14 slows down it’s possible that both systems get close enough to one another where they shear each other apart and remain weaker tropical waves. If Tropical Storm Laura tracks far enough west, it may end up run over the colder waters churned-up in the wake of Tropical Depression 14 causing the storm to weaken.

In the end there are more questions than answers when it comes to the when, where and strength of these storms when they approach the Gulf Coast. However it looks like we will see a rare event take place where we will have two separate tropical systems in the Gulf of Mexico at the same time.

Impacts on Central Illinois

The storms will help amplify an upper-level ridge over the Midwest early next week resulting in temperatures climbing into the mid 90s. It appears that some remnant moisture from the tropical systems could interact with a system coming in from the west to bring a chance of rain to Central Illinois Thursday and Friday of next week. The 6-10 Day Outlook from the Climate Prediction Center calls for above average precipitation and above average temperatures between Thursday, August 27th and Monday, August 31st as a result of the remnants of the two tropical systems.

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