Much Needed Rainfall Heading for the Ohio Valley – But is it too much?

The remains of Tropical Storm Bill will move across the Ohio Valley and into the Mid-Atlantic states this weekend before finally moving offshore. The storm, combined with a cold front dropping down from the north will bring locally heavy rainfall to an area that needs it.

Despite heavy snow this past winter, much of the Northeast and Ohio Valley are experiencing a drought as we head into summer. Moderate drought conditions exist across southern portions of Indiana and Ohio, as well as northern Kentucky. Moderate drought conditions are also noted across much of central and southern New England and eastern New York.

Current Drought Conditions across the United States
Current Drought Conditions across the United States

While this weekend’s rains won’t be enough to bust the drought, they will certainly help, especially across the Ohio Valley, where 1 to 3 inches of rain is expected. Flood watches have been posted for much of the area. In the Northeast, rainfall totals of up to an inch are expected, which will certainly help, but the heaviest rain is likely to stay south of the region.

Tropical Storm Bill made landfall near Matagorda Island, Texas late Tuesday morning with maximum sustained winds near 60 mph. The winds quickly diminished once the storm moved inland, but a swath of heavy rain has resulted in widespread flooding from eastern and northern Texas across Oklahoma and into portions of Arkansas and Missouri over the past several days.

Rainfall totals associated with Tropical Storm Bill over the past 5 days:

Healdton, Oklahoma 12.53″
Montague, Texas 12.50″
Alice, Texas 9.03″
Peru, Indiana 6.72″
Corpus Christi, Texas 6.14″
Springfield, Missouri 5.50″
Belleville, Illinois 5.01″
Shreveport, Louisiana 4.79″
Fort Wayne, Indiana 4.53″
Oklahoma City, Oklahoma 2.64″
Houston, Texas 2.51″
Fort Worth, Texas 2.34″

A much drier weather pattern is shaping up for the Southern Plains, which will allow rivers swollen from the heavy rains of May and June to slowly recede over the next week. Seasonably hot weather will move back in with high temperatures in the 90s for much of the upcoming week.

Hurricane Drought Hits a Decade – How Much Longer Will It Continue?

On October 24, 2005, Hurricane Wilma, which at one point was the strongest storm ever recorded in the Atlantic Basin, made landfall near Goodland, Florida as a Category 3 hurricane with top winds near 120 mph. Wilma was the third hurricane and second major hurricane (Category 3 or higher on the Saffir-Simpson scale) to make landfall in Florida during 2005. The previous year, a total of 4 hurricanes (3 major hurricanes) made landfall in Florida. During the same two-year period, Major Hurricanes Katrina and Rita also slammed into Louisiana.

Major Hurricane Strikes 2004-05
Major Hurricane Landfalls 2004-05. Image Courtesy of National Hurricane Center.

 

In the 10 years since Wilma’s landfall, no hurricanes have struck Florida, and no major hurricanes have struck the United States as a whole. This 10-year lull in major hurricane landfalls is unprecedented since hurricane record-keeping began in 1851. The longest lull on record before this was a 9-year lull between August, 1860 and September, 1869. For Florida, the 10-year drought smashed the previous record of 6 years, set between 1979 and 1985.

While some may argue that the lack of landfalls is a good thing, in many ways, it’s also bad. Reports have indicated that over a million people have moved to Florida since 2005, and the vast majority of those people have likely never experienced a hurricane, let alone a major hurricane.  They may not know how to prepare for a storm that could leave them without power for a week or more. They may not know what a mandatory evacuation means or if they are in a mandatory evacuation zone. They may not know where the nearest shelter is. (For Hurricane Preparedness Tips, visit the National Hurricane Center’s Preparedness Page)

In the Northeast, the drought is even worse. While some may argue whether or not Sandy was a hurricane, it only gave New England and New York a glancing blow. The last hurricane to make landfall in New England was Hurricane Bob in 1991. The last hurricane to make landfall on Long Island was Gloria in 1985. Historically, this region gets hit by a hurricane once every 6 years, but it’s been a quarter of a century since the last one hit. That means that there is an entire generation that does not know what it means to experience a hurricane in this region. As with Florida, it’s a matter of when, not if, the next one will hit this region, and they are long overdue.

While most experts expect this to be a fairly inactive hurricane season, that does not mean the landfall drought will continue. By all accounts, 1992 was an inactive season with only 6 named storms, 4 of which became hurricanes. However, one of those hurricanes was Andrew – one of only 3 Category 5 Hurricanes ever to make landfall in the United States.

Will The Hurricane Season Be An Active One?

A team of scientists at Colorado State University led by Dr. Phil Klotzbach released their April forecast for the upcoming Atlantic Hurricane Season. Their forecast calls for 7 named storms, 3 hurricanes, and 1 major (Category 3 or higher) hurricane. These numbers are well below the 30 year averages of 12, 6, and 3 respectively. The forecasts are based on nearly 30 years of statistical data as well as comparisons to previous hurricane seasons. The report mentions that current atmospheric and oceanic patterns are similar to that of 2014. The 2014 Atlantic Hurricane Season, which also saw below normal activity, had 8 named storms, 6 hurricanes, and 2 major hurricanes.

There are many potential factors that ultimately determine how many tropical cyclones form in a given hurricane season. These factors include wind shear, dry air, ocean temperatures, the phase of the El Nino Southern Oscillation, and the location of semi-permanent pressure systems like the Bermuda-Azores High. The April forecast calls for El Nino to persist into the hurricane season which has been linked to less active Atlantic hurricane seasons due to increased wind shear in the main development region. Like in 2014, seas surface temperatures are anomalously low from the Cape Verde Islands west to the Central Atlantic. However, they are warmer than normal in the Gulf of Mexico.

In addition to 2014, Klotzbach’s team identified four other previous seasons with similar atmospheric and oceanic patterns in the Atlantic which were 1957, 1987, 1991 and 1993. One of these years may jump out to long time New England residents because 1991 was the year when parts of the region were struck by Category 2 Hurricane Bob in August and severely impacted by an unnamed hurricane known now as “The Perfect Storm” in October. Hurricane Audrey also caused significant damage in June 1957 along parts of the Louisiana and Texas coastlines. It goes without saying that it is critical residents along vulnerable coastlines prepare for a potential hurricane every year regardless of the pre-season forecasts.

While the potential exists for a below normal hurricane season, this does not mean that it cannot be a destructive or notable season. In 2014 we had Hurricane Arthur make landfall along the Outer Banks of North Carolina in July, disrupting Fourth of July festivities as far north as New England. A Category 2 hurricane, Arthur was the strongest hurricane to make landfall in the United States since Hurricane Ike in 2008 and the earliest hurricane to strike North Carolina. Bermuda was also hit by two hurricanes (Fay and Gustav) a week apart later in the season. Even if there are fewer hurricanes predicted, it does not mean that the strongest hurricanes cannot form. Southern Florida was devastated by Category 5 Hurricane Andrew in 1992, a year with only six named storms.

Many people question the accuracy of pre-season hurricane forecasts as they are on occasion very different from what actually transpires. One of the reasons pre-season forecasts are useful is that they to provide guidance to local, state, and federal officials. If the forecast calls for an active season, governments can take extra steps to prepare should a hurricane head their way. Even though the forecast this time around calls for a below average number of tropical storms and hurricanes, scientists are unable to predict how strong the tropical cyclones that form will be or where they will go. It only takes one storm to make a hurricane season historic so everyone needs to be prepared.

An Early Start to Hurricane Season? It’s Happened Before

Even though the “official” start of the 2015 Atlantic Hurricane Season is on June 1, there have been many cases of tropical storms and even hurricanes that have roamed the Atlantic waters prior to that date. While the majority of these have been weak and remained offshore, there are a few notable storms in our hurricane database. At least one tropical storm has been recorded in the Atlantic Ocean every month of the year with a hurricane being observed every month except February and April. There are many reasons why tropical cyclones tend to form almost exclusively in the Summer and Autumn. Some of these factors include favorable sea surface temperatures and the northerly progression of the Intertropical Convergence Zone (ITCZ). The ITCZ is responsible for producing many of the precursor disturbances that form into tropical storms and hurricanes but travels between the Tropic of Cancer and Tropic of Capricorn as the year progresses.

During the month of January we have seen one hurricane and one subtropical storm form. In addition, a tropical storm in 2005 and a hurricane in 1954 formed in December and lasted into the following January. One of the most unusual early season tropical cyclones was a recently discovered hurricane that developed from a non-tropical low pressure in the open Atlantic southwest of the Azores on January 1st, 1938. The storm tracked south and then southwest, an atypical storm motion in the open Atlantic, while acquiring tropical characteristics eventually becoming an 80 mph hurricane. The storm dissipated on January 6th well to the east of the Lesser Antilles with minimal impacts. Another quirky hurricane impacted parts of the Lesser Antilles in January 1955. It moved from the northeast to the southwest into the Caribbean Sea causing $600,000 in damage. Operationally, this hurricane was not recognized as a tropical cyclone until January 2nd so it was given the first name on the 1955 season list which was Alice. However, Alice actually became a tropical storm on December 30th, 1954 meaning it should have been given the next name on the 1954 list. As a result, the 1954 hurricane season officially has two storms that start with the letter A while 1955 does not have an A named storm.

February and March are far less interesting with only one tropical cyclone each. The February event formed on February 2nd, 1952 and impacted parts of Mexico, Cuba, and Florida with minimal impacts. It was a quick moving storm that quickly became extra-tropical after emerging into the Atlantic from Florida. This tropical storm was dubbed the “Groundhog Day” Storm. Moving on to March, the only tropical cyclone to exist occurred in 1908. Like Hurricane Alice, this unnamed hurricane developed northeast of the Lesser Antilles and moved towards the southwest. This hurricane had peak winds of 100mph, a Category 2 hurricane, and caused some damage to St. Bart’s though the monetary value is not known.

Tropical cyclone activity in April is also fairly rare with only one tropical storm and one subtropical storm in our database. The first storm formed in 1992 and was a short-lived subtropical cyclone that was located well to the northeast of Puerto Rico. The second and more interesting storm was Tropical Storm Ana in 2003. A non-tropical storm system formed on April 18th southwest of Bermuda. Convection began to develop around the system as it gradually acquired tropical characteristics. The storm became subtropical on April 20th while west of Bermuda and within 24 hours was considered a fully tropical system. Ana caused breezy weather and dropped over 2 inches of rainfall on Bermuda as it finally began to move off to the east. Bermuda would be the only country that would see direct impacts from Ana as a tropical cyclone but Ana would later bring breezy conditions to the Azores and rain to the United Kingdom as a post-tropical cyclone. Swells from Ana also impacted the United States and killed two when a boat capsized off of Jupiter Inlet, Florida.

The month of May has seen 24 tropical or subtropical cyclones develop since the official hurricane database began in 1851. While this number is much higher than any of the earlier months, it averages to one event every six or seven years. The last tropical cyclone to form in May was Tropical Storm Beryl in May 2012. As the name would imply, May 2012 also saw the formation of Tropical Storm Arthur about a week prior. While both storms impacted the United States, Arthur only caused minimal damage while Beryl produced $148,000 in damage and killed one person. Only three years featured two pre-season events, 1887, 1908, and 2012. The strongest pre-season hurricane was Hurricane Able which formed in May 1951. Able become a Category 3 hurricane with maximum sustained winds of 115mph. Despite its ferocity, Able stayed offshore and caused minimal damage to the United States. Prior to becoming a major hurricane off the North Carolina coast, Able did a counter-clockwise loop north of the Bahamas. A complete list of January-May subtropical storms, tropical storms, and hurricanes in included below.

Name Month Year Intensity Max. Winds
Unnamed May 1863 Cat. 2 Hurr. 105mph
Unnamed May 1865 Trop. Storm 60mph
Unnamed May 1887 Trop. Storm 70mph
Unnamed May 1887 Trop. Storm 60mph
Unnamed May 1889 Cat. 1 Hurr. 80mph
Unnamed May 1890 Trop. Storm 60mph
Unnamed March 1908 Cat. 2 Hurr. 100mph
Unnamed May 1908 Cat. 1 Hurr. 75mph
Unnamed May 1916 Trop. Storm 60mph
Unnamed May 1932 Trop. Storm 50mph
Unnamed May 1933 Trop. Storm 45mph
Unnamed May 1935 Trop. Storm 60mph
Unnamed January 1938 Cat. 1 Hurr. 80mph
Unnamed May 1940 Trop. Storm 60mph
Unnamed May 1948 Trop. Storm 50mph
Able May 1951 Cat. 3 Hurr. 115mph
Unnamed February 1952 Trop. Storm 50mph
Alice May 1953 Trop. Storm 70mph
Alice-2 Dec./Jan. 1954/1955 Cat. 1 Hurr. 80mph
Arlene May 1959 Trop. Storm 60mph
Alma May 1970 Cat. 1 Hurr. 80mph
Alpha May 1972 Subtrop. Storm 70mph
Unnamed May 1976 Trop. Storm 50mph
Unnamed January 1978 Subtrop. Storm 45mph
Arlene May 1981 Trop. Storm 60mph
Unnamed April 1992 Subtrop. Storm 50mph
Ana May 2003 Trop. Storm 60mph
Zeta Dec./Jan. 2005/2006 Trop. Storm 65mph
Andrea May 2007 Subtrop. Storm 60mph
Arthur May 2008 Trop. Storm 45mph
Alberto May 2012 Trop. Storm 60mph
Beryl May 2012 Trop. Storm 70mph

While tropical storms and hurricanes do not often form during the winter and spring months in the Atlantic, a total of thirty-two events have occurred since our official database started in 1851. While the majority of these stay away from land and are weak, their genesis and track are often unusual. Research has been done to correlate early season tropical cyclones with the total number of tropical cyclones but there is no significant connection. Some seasons can start early but still have below normal activity overall (1992 is a great example) while a season with a late start can produce an above normal amount of tropical cyclones. We haven’t seen a pre-season storm in the last two years and with six weeks to go before June 1st, it has yet to be seen if Tropical Storm Ana forms during in April or May.

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