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Chantal Barely Alive, Bringing Heavy Rains to Haiti and the Dominican Republic

By: Dr. Jeff Masters, 3:24 PM GMT on July 10, 2013

An Air Force hurricane hunter aircraft criss-crossing Tropical Storm Chantal this morning was barely able to find a closed circulation, and measured top winds of 45 mph at 10:10 am EDT in a region of heavy thunderstorms just south of the Central Dominican Republic coast. High wind shear of 20 - 30 knots, combined with dry air and the storm's exceptionally fast forward movement of 25 - 30 mph have seriously weakened Chantal, even before it has encountered the high mountains of Hispaniola and Cuba. Visible satellite loops show that Chantal has a modest area of heavy thunderstorms that are affecting Haiti and the Dominican Republic. Chantal's rains are a serious threat for Haiti, where deforestation of the nation's mountainous hillsides has left the nation highly vulnerable to flooding. In mid-June, heavy rains in Haiti triggered flash floods that killed at least six people and impacted 7,000 families. In October 2012, flooding from Hurricane Sandy killed 60 people and damaged or destroyed more than 18,000 homes. Drought conditions this year over the nation have left the soil hard and impervious, increasing the risk of rapid run-off from heavy rains. Approximately 320,000 people live in makeshift tent shelters in Haiti, three years after the devastating January 2010 earthquake that killed 220,000 people.

Figure 1. Latest satellite image of Chantal.

Forecast for Chantal
The 8 am EDT Wednesday wind shear forecast from the SHIPS model calls for shear to remain in the high range, 20 - 35 knots, into Thursday. This high shear, combined with Chantal's expected passage over the high mountains of Cuba and the continued presence of dry air, will likely destroy the storm by Friday. Wind shear will likely fall to the moderate range once Chantal moves north of Cuba, so there will be the possibility of regeneration in the waters off the coast of Florida if Chantal does dissipate.

Elsewhere in the Atlantic, none of the reliable forecast models are predicting formation of a tropical cyclone for the coming seven days.

Figure 2. Departure of precipitation from average for the past two weeks over the Southeast U.S. shows many areas have received over 400% of their normal precipitation. Image credit: NOAA/HPC.

Figure 3. Soil moisture over the U.S. on July 8, 2013, ranked as a percentage of the greatest moisture levels on record for the date. Large areas of the Southeast U.S. are near the wettest levels ever observed, above the 99th percentile in soil moisture. Image credit: NOAA/CPC.

Southeast U.S. vulnerable to flooding
If Chantal or its remnants brings heavy rains to the Southeast U.S. early next week, as some of the current track models are predicting, the storm could cause major damaging flooding. The soils in the Southeast are saturated and many rivers are already in flood, due to last week's extreme jet stream pattern that set up a fire hose of tropical moisture that streamed inland from the Florida Panhandle through Georgia, South Carolina, and North Carolina. Soils over large areas of the Southeast U.S. are near the wettest levels ever observed for this time of year--above the 99th percentile in recorded history. It's remarkable that most of Georgia, South Carolina, and North Carolina were in moderate or greater drought at the beginning of the year. Portions of Central Georgia were in exceptional drought--the most extreme category of drought.

Figure 4. MODIS image of Typhoon Soulik taken at 02:10 UTC July 10, 2013. Image credit: NASA.

Powerful Typhoon Soulik a threat to Taiwan and China
Earth's most powerful tropical cyclone so far in 2013 is Typhoon Soulik, a Category 4 storm with 140 mph winds in the Western Pacific. Soulik has weakened slightly from its peak winds of 145 mph earlier today, but is expected to maintain Category 4 strength into Thursday, then weaken to Category 3 strength under the influence of high wind shear of 20 - 25 knots, before hitting the northern end of Taiwan on Friday. Soulik will then make landfall in China near Fuzhou on Saturday, most likely as a Category 1 typhoon. Soulik is the third Category 4 storm globally so far in 2013 (joining January's Tropical Cyclone Narelle and Tropical Cyclone Felleng in the Southern Indian Ocean.) Earth has not yet seen any Category 5 storms in 2013.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.