It is the first day of the Atlantic Hurricane Season, and already the WDVM weather team is looking at a potential storm forming in the Gulf of Mexico over the next couple of days.
Today starts the Atlantic hurricane season and already eyes will be looking to the Gulf of Mexico as the remnants of hurricane Agatha move across southern Mexico. If the disturbance does become tropical in nature, it will be the first Atlantic named storm and will be called “Alex”. Looking ahead to where this potential disturbance may go…Well, it is still up in the air, but more spaghetti models are leaning toward a trek toward Florida. So looking back throughout history, where do storms typically form? Locations for formation are certainly different as the oceans heat and cool under different circumstances and at different months throughout hurricane season. For example in the month of June formation is usually in the Gulf of Mexico and the Caribbean sea, with many storms either crossing Florida or moving into parts of Texas or for that matter staying away from the east coast and out to sea. This is noted quite well with the two favored tracks. (See graphic below) By September, the peak of hurricane season, storms usually come off the coast of Africa and travel hundreds, if not thousands of miles across the Atlantic to either become ship storms or make landfall somewhere along the east coast. By the end of the season, which is November, many storms lose their punch and as water temperatures start to cool down some, the formation of storms are usually found to be in the Caribbean or western Atlantic and primarily weak, staying out to sea and away from the east coast.
So what are the predictions for this season? Well once again, an above-normal season is anticipated, as forecast by all the latest predictors, like NOAA and Colorado State. The names start with “Alex” and end with “Walter”, but unlike in past seasons, there is a slight change when it comes to naming storms. In past years, if the original list of names was used up, then the national hurricane center would shift to using the Greek alphabet, but as of 2021, there is a secondary list of names, as the Greek list has been dropped. Why did they do that? The answer is quite simple. This is because the use of Greek alphabet names “Creates a distraction from the communication of hazard and storm warnings and is potentially confusing”, said the World Meteorological Organization. From now on, instead of using the Greek alphabet, the WMO will use a supplemental list of names if the original list is exhausted. As it stands, the NHC reuses the same group of names every six years, unless a storm name is retired, and the only way a name is retired is if they were so deadly, or destructive, that the future use of the name would be insensitive.
So how accurate have these predictions been from NOAA and Colorado state? To calculate the accuracy of hurricane season predictions, we measure the first predictions of NOAA and CSU to the actual storms and hurricanes at the end of the year. NOAA has held more accurate predictions, but they use a predicted range, rather than the single number that Colorado state university offers. Over the last 1o years, the accuracy percentage rate, from two of the most know predictors, has NOAA beating out Colorado state when it came to predicting a number of named storms, and when it came to predicting a number of major hurricanes by 20%!! Granted it is a small sample size, but it looks like NOAA is doing something right.
As mentioned before, this hurricane season is expected to be above normal and is actually the seventh consecutive above-average hurricane season. NOAA says there is a 65% chance of an above-normal season, with increased activity due to several climate factors, including 1) being in a la Niña cycle 2) warmer-than-average sea surface temperatures in the Atlantic ocean and the Caribbean sea 3) weaker tropical Atlantic trade winds and lastly, 4) an enhanced west African monsoon. When the continent of Africa is quite wet, that will look to translate across to the U.S., but even though it might be an above-average season, that doesn’t guarantee that we will locally see an active period of storms. As a matter of fact, D.C. And the surrounding region usually gets spared catastrophic damage; however, we cannot let down our guard for a second. Looking back in history, there have been 19 unnamed and named storms that have had a major impact on our area. The last one was Irene in 2011. When Irene came through our area, it prompted the Maryland governor, Martin O’Malley, to declare a state of emergency along with the governor of Delaware, Jack Markell, ordering visitors to evacuate the Delaware beaches. In Washington, D.C., the forecast arrival of Hurricane Irene caused the postponement of the dedication ceremony for Martin Luther King JR. Memorial, along with the city placing thousands of sandbags around in areas that typically flood, like Washington metro station entrances. Hopefully, we do not see anything like that around here this hurricane season, as we once again wait to see what unfolds over the next six months.