Hurricane season expected to intensify in mid/late August

AUSTIN (KXAN) – As the 2022 Atlantic hurricane season gets off to a slower start than in recent years, several variables are coming together for a rapid increase in tropical activity in mid-August – which could possibly bring relief. rain in Texas.

June and July are generally calmer months in the Atlantic Basin, with limited tropical storm and hurricane activity. Eighty-five percent of major hurricanes develop after August 20, according to Phil Klotzbach, who works at Colorado State University and develops forecasts for Atlantic hurricanes between August and October, typically peak times for the development.

At the start of August 2020, the Atlantic hurricane season has already spawned seven tropical storms and two hurricanes. At the beginning of August 2021, we had already identified four tropical storms and one hurricane.

This Atlantic hurricane season has produced only three tropical storms with relatively minor impacts.

Tropical cyclone climatology, with most activity after August 1 (Natl. Hurricane Center)

While it appears to be a calm season so far, it’s directly in line with the National Hurricane Center’s 30-year averages below, with just three typical named storms through August 3.

Number Named systems Hurricanes Major hurricanes
1 June 20 August 11 1 Sep
2 Jul 17 August 26 Sep 19
3 August 3 7 Sep October 28
4 August 15th 16 Sep
5 August 22 Sep 28
6 August 29 October 15
seven 3 Sep November 15
8 September 9
9 16 Sep
ten Sep 22
11 October 2
12 October 11
13 October 25
14 November 19
Course of the average Atlantic season (1991-2020). Date on which the following number of events would normally have occurred. (National Hurricane Center)

The Atlantic hurricane season intensifies from August due to a variety of factors including warmer ocean waters, less Saharan dust in the atmosphere and more disturbances crossing the ocean from Africa, which act as “seedlings” for tropical storms.

We are tracking an expected increase in disturbances off the African coast in mid-August. These tropical waves can serve as embryos for the development of tropical storms as they cross the Atlantic to the west. As Joe Bastardi of Weatherbell.com writes, “the wave train will start to work,” with wetter than normal weather expected in the interior of Africa where these seedlings were born.

Predicted rainfall anomalies over Africa from August 10 to 17
Predicted rainfall anomalies over Africa from August 10 to 17, showing above normal rainfall in interior parts of North Africa (Weatherbell.com)

The final variable expected to lead to increased tropical activity in mid-August is the Madden-Julian Oscillation, or MJO. We can think of the MJO as a large-scale area of ​​rising or falling air that can either enhance or suppress the development of a storm.

As an area of ​​storm-supporting upwelling moves over the Atlantic in mid to late August, large-scale upwelling will replace large-scale sinking, making conditions more favorable for tropical development. A pattern like this led to a hurricane outbreak in late August 2020.

Image showing low chance of tropical cyclones forming in the Atlantic before August 12.  The training would probably take place after this date.
The likelihood of a tropical cyclone forming through August 12 remains low. The ramp-up of activity would probably occur after this date. (ECMWF Model)

While all of these variables will lead to increased tropical activity in the Atlantic, it will not happen immediately. Long-term forecast models suggest that the current lull in activity lasts until August 12, with an increase between August 12 and 20.

While we expect a sharp increase in hurricane activity, it is impossible to predict where storms may go until they form. CSU forecasters are diagnosing an above-normal 59% chance of a hurricane hitting Texas this year (average: 36%) and a 28% chance of a major hurricane hitting (average: 16%).

Stay with the KXAN First Warning Weather Team for the latest news throughout the hurricane season.

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