Hurricane Central

Can Erika Quench Three Separate Droughts?

Tropical Storm Erika has fizzled, but one impact somewhat regardless of intensity is its potential for heavy rain.

(FORECAST: Erika's Remnant Flood Threat)

Torrential rain over the mountainous island of Dominica proved deadly and destructive Thursday, and over 24 inches of rain soaked parts of the southern Dominican Republic Friday night.

A recently published study examining a 58-year period found that, contrary to conventional wisdom, tropical cyclones really don't help Southeast U.S. droughts.

Despite that, Erika's remnant rain, if not triggering flash flooding, would at least be a welcome sight in three separate drought areas.

Drought monitor analysis over Puerto Rico and the Virgin Islands as of August 25, 2015. The darker brown and red shadings correspond to areas of worse long-term drought.
(NOAA/USDA/NDMC)

Puerto Rico/Virgin Islands

Arguably the nation's most severe water crisis other than California is in Puerto Rico.

In early August, 20 of the island's 78 municipalities were declared federal disaster areas. Reservoirs were drying up and water rationing was put in place for the first time since the mid-1990s.

(MORE: Puerto Rico's Drought)

It was the fourth driest July on record in San Juan, the territory's capital, and the year-to-date rainfall deficit still tops 10 inches as of late August. Puerto Rico's water and sewer company announced plans early in August to fund a cloud seeding project in hopes of triggering rain-producing clouds.

The drought is worst in the east, which received little rainfall from the remnant of what once was Hurricane Danny earlier in the month. On the other hand, western Puerto Rico picked up 0.5 to 3 inches of rain from Danny's remnants.

Erika's quick movement along with the lion's share of heavy rainfall remaining well to the south, limited the flash flooding you typically see in this part of the world from tropical cyclones.

Often, a return of rain to an area suffering a severe drought comes in the form of flooding downpours running off into reservoirs, but not necessarily soaking deep into drought-hardened soil.

Erika may have been a rare "Goldilocks" situation for drought relief in Puerto Rico and the Virgin Islands. Rainfall not too heavy, not too light, but just right.

That said, the region needs several more widespread rain events to fully replenish reservoirs and soil moisture to normal values.

(FORECAST: San Juan | St. Croix)

Florida Drought Monitor analysis as of Aug. 25, 2015. (NOAA/USDA/NDMC) — Florida Drought Monitor analysis as of August 25, 2015. The darker brown and red shadings correspond to areas of worse long-term drought.
(NOAA/USDA/NDMC)

South Florida

Despite being surrounded on three sides by water – Atlantic Ocean, Gulf of Mexico, Florida Straits – South Florida's drought intensified into what is typically the wet season.

Year-to-date rainfall deficits through Aug. 27 were nearly 17 inches in Fort Lauderdale, 12 inches in Miami, and 11 inches at West Palm Beach.

Through Aug. 20, Fort Lauderdale International Airport had seen its driest wet season (since May 1) on record, with only 36 percent of its average rain, according to the National Weather Service in Miami.

NWS-Miami also said water levels in wells across metro Broward County, Miami-Dade County and the Everglades, were running only 10-30 percent of average for late August. Lake Okeechobee's water level was running about 1.5 feet below average for late August. Year-round outdoor water restrictions were enacted by the South Florida Water Management District.

Erika's surge of moisture is pushing into South Florida and could linger for several days, bringing locally heavy rainfall through early week.

Again, this could prove "too much of a good thing because flash flooding possible. However, it seems likely the long-term hydrologic drought will at least feel a sizable dent.

(FORECAST: Miami)

Drought monitor analysis over the southern U.S. as of August 25, 2015. The darker brown shadings correspond to areas of worse long-term drought.
(NOAA/USDA/NDMC)

Southeast

Droughts by their very nature are slow-evolving, but one of the fastest developing droughts in the U.S. has taken shape over the southern U.S. this summer.

May through July was the fourth hottest on record in North Carolina, and among the top 10 such hottest periods in South Carolina, Florida and Louisiana, according to NOAA's National Centers for Environmental Information.

Rainfall deficits since June 1 are in the 3-6 inch range from parts of the Carolinas into Middle and south Georgia.

Erika's remnant moisture and an existing trough of low pressure in the upper atmosphere should allow pockets of locally heavy rainfall to persist in parts of Georgia, Florida, Alabama and the Carolinas.

This remnant may linger into much of this week ahead with locally heavy rainfall possible.

(FORECAST: Macon, Georgia | Tallahassee, Florida)