Unusual November Tropical Action: Watching Invests 96L and 94E

Unusual November Tropical Action: Watching Invests 96L and 94E

It may be Veterans Day, but the Atlantic and East Pacific hurricane seasons still may not be over just yet. A trough of low pressure located southwest of the Azores – recently designated Invest 96L – has a chance to develop some subtropical characteristics over the next few days as it moves northeastward. In the Eastern Pacific, Invest 94E is becoming better organized quickly this afternoon and could become a tropical depression over the next couple days as it moves westward to west-northwestward.

96L could acquire some subtropical characteristics this week

Atlantic Tropical Weather Outlook for Saturday, November 11, 2017, 7:00 p.m. EST. (Source: National Hurricane Center)

As of 18:00 UTC Saturday, Invest 96L was centered near 30.2°N 33.9°W. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1016 mb. 96L currently consists of a large surface trough, interacting with an upper-level low. Shower and thunderstorm activity is not well organized at this time. However, 96L could acquire some subtropical characteristics over the next few days as it moves northeastward towards the Azores in a marginally favorable environment. The National Hurricane Center (NHC) gives 96L a 10 percent chance of development within 48 hours, and a 40 percent chance within five days. The next name on the Atlantic naming list is Sean. However, it is possible that this system may not be operationally classified if it does become a subtropical cyclone, because NHC often treats non-threatening marginal subtropical cyclones as extratropical lows operationally (with the most recent case being an unnamed subtropical storm in December 2013). It is worth noting that the Atlantic has not seen two or more named storms form in the month of November since 2005 (Tropical Storm Rina formed earlier this week). Residents of the Azores should monitor the progress of 96L, but it is uncertain if it will just be a non-tropical low or a subtropical cyclone.

94E becoming better organized over Eastern Pacific

Rainbow loop of Invest 94E, located over the Eastern Pacific. (Source: NOAA)

An area of low pressure has formed about 1000 miles southwest of Baja California over the Eastern Pacific, and is gradually getting better defined. This system – Invest 94E – has a medium chance of becoming a tropical depression during the next 48 hours. As of 18:00 UTC Saturday, 94E was centered near 11.5°N 118.7°W. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1007 mb. 94E is becoming better organized this afternoon, and deep convection has been increasing with the disturbance. The NHC gives 94E a 50 percent chance of development within both 48 hours and five days. The next name on the East Pacific naming list is Todd. 94E is unusually far west for a November disturbance in the Eastern Pacific, as most November storms in that basin form close to Mexico or Central America.

I will be back with another post tomorrow on these unusual November systems.

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