Erika Dissipates

By: Dr. Jeff Masters , 2:34PM,GMT on August 29,2015

Tropical Storm Erika charged into the teeth of Hispaniola's high mountains on Friday night, and emerged from the encounter shattered, without a closed circulation, and is no longer a tropical storm. Measurements on Saturday morning from an Air Force hurricane hunter aircraft failed to find any tropical storm-force winds associated with Erika, and the plane did not find any westerly winds, showing the the storm had degenerated to a tropical wave.


Figure 1. Erika as seen from the International Space Station on Saturday morning, August 29, 2015. Image credit: Scott Kelly.

Erika belted the Dominican Republic and Haiti with torrential rains overnight; a Personal Weather Station (PWS) in Barahona in the Dominican Republic recorded 24.26" in rain between 1 pm Friday and 7 am Saturday. Other nearby locations showed rainfall amounts of 4" or below, so widespread flooding may not have occurred in the Dominican Republic. Erika's worst flooding was on the island of Dominica, where at least 20 people are confirmed dead. Canefield Airport on Dominica recorded 12.62" (320.6 mm) of rain in twelve hours on Wednesday night and Thursday morning from Erika.


Figure 2. Radar-estimated precipitation from Tropical Storm Erika from the San Juan, Puerto Rico radar. Erika's rains were a disappointment in eastern Puerto Rico, where severe to extreme drought conditions have led to drastic water rationing. The capital of San Juan received just 0.22" of rain on Friday, leaving them ten inches below the 33" average rainfall for this time of year.

Forecast for Erika's remains
The remnants of Erika will likely produce total rainfall accumulations of 3 - 6" across portions of the Dominican Republic, Haiti and eastern and central Cuba through Sunday, with 1 - 3" across the Turks and Caicos Islands and southeastern and central Bahamas. Rainfall amounts of 3 to 5 inches, with locally heavier amounts, are possible across southern and central Florida beginning on Sunday. Eastern Cuba, which is suffering its worst drought since at least 1901, is hoping that Erika's rains prove bounteous. Reuters reported Friday that Cuba will begin a two-month cloud-seeding campaign in September over the eastern part of the island in hopes of easing the drought.

The 00Z Saturday (8 pm EDT Friday) runs of our top three models for predicting tropical cyclone genesis had one model--the UKMET--showing regeneration of Erika into a tropical depression along the west coast of Florida on Tuesday. The other two models--the European and GFS models--showed no regeneration. The 8 am EDT Saturday run of the SHIPS model showed wind shear would drop to a moderately high 15 - 20 knots off the west coast of Florida by Tuesday; sea surface temperatures will be a very warm 30°C (86°F). These conditions support potential slow regeneration of Erika.

New tropical wave moving off the coast of Africa
A strong tropical wave (Invest 99L) with plenty of spin and heavy thunderstorm activity moved off the coast of Africa on Saturday, and has the potential to become a tropical depression early in the week as it moves west-northwest or northwest near or over the Cape Verde Islands at 10 - 15 mph. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 50% and 70%, respectively. This disturbance will likely move too far to the northwest to be a threat to the Caribbean islands.


Figure 3. Double feature: Hurricanes Ignacio and Jimena spin across the Pacific on Friday afternoon, August 28, 2015 in this true-color VIIRS image. Image credit: NOAA.

Hurricane Ignacio headed towards a brush with Hawaii
Category 3 Hurricane Ignacio continues to slowly intensify as it heads northwest towards Hawaii. Satellite loops on Saturday morning showed a well-organized storm with plenty of heavy thunderstorms surrounding a prominent eye. Ignacio is over warm waters with light to moderate wind shear, conditions that favor continued intensification. An Air Force hurricane hunter aircraft will investigate Ignacio on Saturday afternoon. Our top models for predicting hurricane tracks continue to show that Ignacio will pass about 300 miles of Hawaii on Tuesday--close enough to bring heavy surf, but not close enough to bring tropical-storm force winds or flooding rains. The 06Z (2 am EDT) Saturday run of the HWRF model showed Ignacio's main rain swath missing Hawaii, with some scattered areas of 2 - 4" of rain affecting portions of the islands. Hawaii probably need not worry about impressive Hurricane Jimena, which intensified rapidly to a Category 4 storm with 150 mph winds overnight. Long-range projections from the GFS and European models continue to show Jimena recurving late in the week well before reaching Hawaii.

There will be a new post on Sunday.

Jeff Masters