Tropical Threat to Florida Next Week; Floods Persist in Texas, Europe

The next named storm for the Atlantic will be named Colin, and there is one potential area to watch for its development early next week: over the Western Caribbean, where a large area of low pressure laden with plenty of tropical moisture is expected to form. This low and its associated moisture will ride up to the north-northeast into the southern Gulf of Mexico on Sunday, and start spreading heavy rains over Florida on Monday. About 10% - 30% of the members of the ensemble runs of the 00Z Thursday GFS and European models showed a tropical depression forming in the Gulf of Mexico or Western Caribbean near Mexico's Yucatan Peninsula early next week, with the storm making landfall along the west coast of Florida on Tuesday. There will be some high wind shear and dry air over the central Gulf of Mexico early next week in association with an upper-level trough of low pressure, and these conditions will likely interfere with development, making intensification into a hurricane unlikely. Regardless of development, heavy rains will be the main threat from this system, and  3 - 5" of rain can be expected over much of Florida during the period Monday - Tuesday. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave 2-day and 5-day odds of development of 0% and 30%, respectively. Given that the 00Z Thursday runs of all three of our reliable models for predicting tropical cyclone genesis--the GFS, European, and UKMET models--all showed some degree of development, I think the 5-day odds of development should be bumped up to 40%.

If Colin were to develop next week, it would be the earliest occurrence of the third Atlantic tropical storm of a calendar year in records going back to 1851, beating out an unnamed storm from June 12, 1887. One important caveat is that systems as weak as Bonnie could easily have been missed or underreported in the era before satellite observations.


Figure 1. Predicted precipitation for the 7-day period ending 8 am Thursday, June 9, 2016. A tropical disturbance is predicted to bring rainfall amounts of up to 3 - 5" inches to most of Florida, with most of the rain falling Monday and Tuesday. Image credit: National Weather Service.


Figure 2. Surface wind depiction of Tropical Depression Bonnie at 7 am EDT June 2, 2016, from earth.nullschool.net.

Bonnie is back
Bonnie came back to life as a tropical depression near the Outer Banks of North Carolina at 11 am EDT Thursday, when NHC began issuing advisories on the system again. Satellite loops on Thursday morning showed that Bonnie had regained its closed surface circulation, with a modest area of heavy thunderstorms near the center. These thunderstorms will likely bring 1 - 3" of rain to the Outer Banks of North Carolina through Thursday night. Bonnie is headed east-northeast out to sea, and will not cause any more trouble to land areas after Thursday. Bonnie will be under light wind shear and over the relatively warm 26°C (79°F) waters of the Gulf Stream through Thursday night, which may allow intensification to a minimum-strength tropical storm with 40 - 45 mph winds by Friday morning. Later on Friday, Bonnie will encounter waters of 24°C (75°F) and cooler, which should cause dissipation by this weekend.

The 2016 version of Tropical Storm Bonnie was the seventh incarnation of the storm, which made its first appearance back in 1980. Only five other Atlantic storms have had more appearances than Bonnie--Arlene with ten, Florence with nine, Cindy with eight, Dolly with eight, and Frances with eight. The seven versions of Bonnie have made landfall in six different years (if we include landfalls at tropical depression strength). Only two other named storms, Arlene and Beryl, have also made landfalls as a tropical depression or stronger in as many as six different years:

BONNIE – 1980 – No; 1986 – Landfall Texas; 1992 – Landfall Crossing the Azores; 1998 – Landfall North Carolina; 2004 – Landfall Florida; 2010 – Landfall Florida; 2016 Landfall as Tropical Depression, South Carolina.

ARLENE – 1959 – Landfall Louisiana; 1963 – Landfall Bermuda; 1967 – No; 1971 – No; 1981 – Landfall Cuba; 1987 – No; 1993 – Landfall Texas; 1999 – No; 2005 – Landfall Florida; 2011 – Landfall Mexico.

BERYL – 1982 – Landfall Cape Verde Islands; 1988 – Landfall New Orleans; 1994 – Panama City, Florida; 2000 – Landfall Mexico; 2006 – Landfall Nantucket; 2012 – Jacksonville Beach, Florida.
 
Thanks go to wunderground member Mark Cole for these stats.

First tropical depression of the season likely in the Eastern Pacific this weekend
In the Eastern Pacific, satellite loops show that an area of heavy thunderstorms located about 1000 miles south-southwest of the southern tip of the Baja Peninsula has not improved in organization over the past day. However, this disturbance (91E) is likely to develop into the Eastern Pacific's first tropical cyclone of the year this weekend, according to recent runs of the GFS and European models. The disturbance is moving west-northwestward at about 10 - 15 mph, and is not a threat to any land areas. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave 91E 2-day and 5-day odds of development of 70% and 90%, respectively. Should 91E become a tropical storm, it would be named Agatha. The first named storm of the year in the Eastern Pacific typically forms on June 10, so we would be very close to the climatological pace we expect.


Figure 3. An aerial view of homes in the Horseshoe Bend area on the banks of the Brazos River in north central Texas on Wednesday, June 1, 2016. Residents of some rural southeast Texas counties braced for more flooding along the river that is expected to crest at a record level just two years after it had run dry in places because of drought. (Brandon Wade/Star-Telegram via AP)

Deep water in the heart of Texas
Heavy rains continue to plague much of the Southern Plains, thanks to a weak, slow-moving upper-level low parked over west Texas and a persistent feed of very rich tropical air into the region from the Caribbean and Gulf of Mexico. The upper low will trudge toward central and eastern Texas by Friday, then stall out before drifting southwest. Eventually, the low will get sheared out and/or picked up by a stronger upper trough moving through the eastern U.S. Until then, Texas will be vulnerable to multiple rounds of heavy thunderstorms packing torrential rain. After the Brazos River west of Houston hit a record crest on Monday (with levels reaching a new peak on Thursday), the river overflowed more than 200 miles to the northwest, in Parker County west of Fort Worth, overnight Tuesday night (see Figure 3). On Wednesday afternoon, flash floods pounded the Lubbock area as an estimated 3” to 5” of rain fell over parts of the city in a two-hour period. Overnight on Wednesday night, a mesoscale convective system (MCSs) formed over central Texas. After dumping more than 4” over parts of the San Antonio area, this MCS was drifting north on Thursday morning, while new showers and storms were developing to its east in the Houston area.

The exact location of the heaviest Texas downpours amid more general rains will evolve over the next couple of days based on where rain-cooled outflow and other hard-to-predict small-scale weather features set up. The high-resolution HRRR model indicates that Thursday’s heaviest rain will push northeast toward Louisiana, Arkansas, and Oklahoma late in the day, with the 4-km NAM model suggesting another MCS will bloom around the pre-existing circulation over central TX by Friday. Flash flood watches are plastered across much of central TX and OK, and river flooding may become an increasing concern as the wet days roll onward.


Figure 4. Infrared satellite imagery from NOAA’s GOES satellite shows a mesoscale convective complex over central Texas at 1415Z (10:15 am EDT) Thursday, June 2, 2016. Additional thunderstorms were forming over southeast TX. Image credit: NASA/MSFC Earth Science Office.

Historic flooding across France, Germany
The death toll from a week of flooding rose to at least nine on Thursday as torrential rains continued to inundate parts of northwest Europe. Warm, moist air has been flowing into the region around a cut-off upper low located near Austria. With the low stranded in place, thunderstorms have been recurring day after day, with severe weather threats extending across much of the continent on Thursday (see Figure 5).


Figure 5. Severe weather outlook for Europe issued early Thursday, June 2, 2016. Image credit: European Storm Forecast Experiment (ESTOFEX).


Some of the worst flash flooding on Wednesday was in parts of southern Germany. The town of Simbach am Inn was devastated by flood waters that cascaded through the center of town, tossing vehicles and leaving behind mounds of debris (see Figure 6 below). At least three people were killed in Simbach am Inn, with several others missing.

Meanwhile, central France has been hit hard by river flooding, where water levels have toppled century-long records in some places. Flood guidance on Thursday from the French agency VIGICRUES targeted the region from Paris south through the Loire Valley as one of the highest-risk zones. Record crests from 1910 have already been broken along the Loing, a tributary of the Seine. Thousands of people have been evacuated across the region. On Thursday, some riverbank sections along the Seine in central Paris were already closed as water flowed into the region from the south. One of the city’s most renowned benchmarks of high water is the statue of a Zouave soldier at the Pont de l’Alma, built in the 1850s. The statue’s feet were covered on Thursday as the water height reached 4.45 meters, its highest level since at least 2001. During the city’s flood of record, in 1910, the water level reached the statue’s shoulders (8.62 meters). The Seine is predicted to crest between 5 and 6 meters on Friday, according to Le Monde. The Guardian has a powerful gallery of flood-related images from Germany and France.

Jeff Masters (tropical], Bob Henson [flooding]


Figure 6. Firemen rescue two women with their boat following heavy floods the day before on June 2, 2016 in Simbach am Inn, Germany. Flash floods from the swollen Inn river took local communities by surprise, trapping children at schools and forcing some residents to flee to their rooftops. Image credit: Sebastian Widmann/Getty Images.


Figure 7.. A man stands on a road flooded by the river Seine after its banks became flooded following heavy rainfalls in Paris on June 2, 2016. Torrential downpours have lashed parts of northern Europe in recent days, leaving four dead in Germany, breaching the banks of the Seine in Paris and flooding rural roads and villages. Image credit: Geoffroy Van der Hasselt/AFP/Getty Images.