Above: GeoColor satellite image of Tropical Storm Cristobal at 1832Z (2:32 pm EDT) Tuesday, June 2, 2020. (tropicaltidbits.com)
The earliest “C” storm in Atlantic hurricane history was named on Tuesday with the upgrade of Tropical Depression 3 to Tropical Storm Cristobal in the southwest Gulf of Mexico. Cristobal will linger for several days, contributing to torrential rains and dangerous floods in southern Mexico and Central America. It will likely then embark on a trek across the Gulf that could bring it to the northern U.S. Gulf Coast as a tropical storm or hurricane this weekend or early next week. Update (noon EDT Wednesday): Cristobal drifted inland just west of Ciudad del Carmen, Mexico, at around 1330Z (9:30 am EDT) Wednesday. At 11 am EDT, Cristobal was located about 15 miles west of Ciudad del Carmen with top sustained winds of 60 mph, moving south-southeast at just 3 mph. Cristobal is now expected to become a depression before moving offshore, heading northward, and likely restrengthening this weekend before reaching the central U.S. Gulf Coast late Sunday or Monday. We'll have a full update on Cristobal later today (Wednesday).
According to the NOAA/NHC National Hurricane Center, Cristobal beat out Tropical Storm Colin (June 5, 2016) as the earliest third system of tropical-storm strength in any Atlantic season going back to 1851.
Cristobal formed in the Bay of Campeche at the north end of a sprawling seasonal circulation called the Central American Gyre (CAG), emerging from the remnants of Tropical Storm Amanda. Amanda formed on Sunday at the south end of the gyre in the Northeast Pacific and moved ashore hours later, triggering deadly flash floods in Guatemala and El Salvador, where at least 17 deaths have been reported (see the weather.com article). Amanda’s remnants then moved around the east side of the gyre and reconsolidated over the Yucatan Peninsula and the Bay of Campeche on Monday.
Understanding of the CAG has grown in recent years, and this helped forecasters anticipate the potential development of Amanda and Cristobal several days in advance (see our post from last Friday, May 29).
Biggest short-term threat from Cristobal: Flooding and mudslides
As Cristobal lingers near the south coast of the Bay of Campeche, it will pull moist southerly flow across Central America and southern Mexico, which will exacerbate flooding woes across the region. Over southeast Mexico, including parts of the Yucatan Peninsula, widespread rainfall totals up to 15 inches and localized amounts of 25 inches of can be expected, according to NHC. As of Tuesday morning, 24-hour rainfall totals included 140 mm (5.5") at Campeche and 131.5 mm (5.18”) at Yucatan.
In the central Yucatan Peninsula, the police station at Canakom, Yaxcabá, reported floodwaters 1.2 meters (4 feet) deep on Tuesday (see tweet below).
Amanda dumped as much as 20 inches of rain near the Pacific coasts of far southern Mexico, Guatemala, and El Salvador. Especially if it strengthens in place, Cristobal will help keep southerly flow pushing inland and upslope across these areas. NHC warns that rainfall totals could reach 35 inches in some of the hardest-hit areas, factoring in the upcoming rains on top of those produced by Amanda.
Longer-term threat from Cristobal: Potential threat to the northern Gulf Coast
Over the next couple of days, weak steering currents will prevail, keeping Cristobal in or near the southern Bay of Campeche. The bay’s concave geography will help support Cristobal’s cyclonic surface circulation. Wind shear will remain light (5 to 10 knots), and sea surface temperatures are very warm there—in the range of 29-30°C (84-86°F)—so Cristobal is expected to slowly strengthen as long as the center remains over water. It appears less likely than earlier thought that Cristobal will keep rotating around the CAG and dissipate over Central America.
By Friday, there is increasing agreement among the GFS and European longer-range model ensembles that Cristobal will begin a generally northward move through the Gulf of Mexico. Both models suggest the center of Cristobal may arc gently toward the left as it traverses the Gulf. If Cristobal does move into the open Gulf, it now it appears most likely that it would come ashore on the northern Gulf Coast somewhere around Sunday or Monday. However, the entire U.S. Gulf Coast should keep tabs on its progress: there is still much uncertainty around the timing, location, and intensity of any possible landfall, and it is far too soon for any confident forecast. Update (11 am EDT Wednesday): The latest official NHC forecast brings Cristobal inland over Louisiana as a tropical storm. The greatest uncertainty lies in how much strength Cristobal may lose over Mexico and how much it may restrengthen over the Gulf.
Even if Cristobal does angle toward the northwest Gulf Coast, the longer-range models—especially the GFS—strongly suggest that rain, flood, and wave impacts will extend well to the east of the center. The full moon of June 5 may add to tidal impacts, depending on the timing and location of any approach.
At least some intensification of Cristobal is possible if it moves through the Gulf as expected. SSTs are above average throughout the Gulf of Mexico. However, oceanic heat content—the warmth of waters below the surface, which can get churned up as a tropical cyclone passed overhead—is still relatively modest outside of the southeast Gulf, given that we are still in astronomical spring (see above). This lack of high heat content would reduce, though not eliminate, the chance of rapid intensification of a northward-moving Gulf system. Values above 75 kJ/sq cm are most closely associated with higher odds of rapid intensification, although it can still occur when OHC is between 50 and 75 kJ/sq cm.
The NHC forecast as of 11 am CDT Tuesday (see above) has Cristobal moving across the central Gulf as a strong tropical storm.
June hurricane history on the Gulf Coast
Tropical storms are not uncommon in the Gulf of Mexico in June; on average, there’s about one every other year. Hurricane landfalls are much more unusual, as noted by Jon Erdman in a weather.com overview. Only six hurricanes have developed in the Gulf since 1950, and just four of those have struck the U.S. Gulf Coast:
—Bonnie, 1986: Category 2 landfall along the upper Texas coast.
—Agnes, 1972: Category 1 landfall in northwest Florida. Agnes went on to briefly reemerge over the Atlantic before making a second landfall as a tropical storm near New York City. Agnes led to 128 deaths and caused catastrophic flooding, especially in Virginia. It was the costliest hurricane in U.S. history up to that point.
—Alma, 1966: Category 1 landfall also in northwest Florida, after reaching Category 3 status in the southeast Gulf. Alma led to 93 fatalities, mainly in Honduras, and caused $210 million in damage (1976 USD).
-—Audrey, 1957: The only Category 3 U.S. Gulf Coast landfall in June since at least 1950. Audrey led to at least 416 deaths in southwest Louisiana and Texas. No other hurricane since Audrey has caused so many deaths in a U.S. state or territory except for Katrina in 2005 and Maria in 2017. A storm surge up to 12.4 feet in southwest Louisiana, with waves as high as 20 feet, joined with water backing up along rivers to inundate 1.6 million acres of land. In Cameron and Lower Vermillion Parishes, 90-95% of buildings were damaged beyond repair.
Alma and Audrey were also the only Gulf of Mexico hurricanes to reach Category 3 intensity in June.
Jon Erdman contributed to this post.
