WetHurricane Season in the Caribbean Climatology and the
Wet/Hurricane Season in the Caribbean Climatology and the 2015 Season in Retrospect Wazita Scott, MSc. Assistant Climate Forecaster Caribbean Institute for Meteorology and Hydrology 2016 Wet/Hurricane Season Caribbean Climate Outlook Forum, May 30 th, Roseau, Dominica.
Wet / Hurricane Season • May/June to November/December • Coincides with the hurricane season • The drivers of both the hurricane season and the wet season and their variability are the same • Relatively high atmospheric moisture, lower wind speeds and warmer temperatures can lead to heat stress – Especially during dry spells
Driver 1: Migration of the Inter-tropical Convergence Zone (ITCZ) ITCZ
Driver 2: Resulting change in strength and northward migration of the sub-tropical (Bermuda-Azores) High Pressure
Driver 3: Sea surface temperature (SST) generally 27 -30°C 27 – 30° C
Driver 4: Migrating tropical waves and other disturbances, which can strengthen and develop to form tropical cyclones
Wet/ Hurricane Season PEAK • September/October – Especially when SSTs are highest and ITCZ is at its most northerly position. END • Is the start of dry season • Triggered by southward migration of the subtropical high and the ITCZ - as a more stable atmosphere develops
Three Months Rainfall Climatology September-October-November (SON) Rainfall June-July-August (JJA) Rainfall Climatological period 1981 -2010
Monthly Rainfall Totals (1971 -2016) Grantley Adams International Airport, Barbados Generated by CAROGEN
Monthly Rainfall Totals (1971 -2016) Maurice Bishop International Airport, Grenada V. C. Bird International Airport, Antigua Zanderij, Suriname Canefield, Dominica Generated by CAROGEN
Monthly Rainfall Totals (1971 -2016) San Juan, Puerto Rico Nassau, Bahamas D Sangster Airport, Jamaica Central Farm, Belize Generated by CAROGEN
Monthly Temperatures (1971 -2016) Canefield, Dominica Nassau, Bahamas D Sangster Airport, Jamaica Maurice Bishop International Aiport, Grenada Generated by CAROGEN
Hurricane Season 2015 Forecast Parameter and 1950 -2000 Climatology (in parentheses) 2015 Predictions Actual Event Named Storms (10) 6 -11 11 Hurricanes (5. 9) Intense Hurricanes (2. 3) 3 -6 0 -2 4 2 * Intense Hurricanes (Cat 3, 4 & 5)
The 2015 -’ 16 Caribbean Drought
In the news – drought!! 2015: record dry in many places • Antigua From August: “No surface water exploitable, 83% desalination” (Antigua & Barbuda Met Services) From October: 100% desalinated water Potworks Dam in Antigua Mona reservoir in Jamaica • Barbados record driest year resulting in water outages in central and northern part of the island. • Dominica Tropical Storm Erika amidst drought: 1. 3 billion EC$ damage and losses. • St. Kitts & Nevis Carraizo reservoir in Puerto Rico water rationing resumes in January 2016 after second driest year on record. No water sold to cruise ships since September. • St. Lucia two driest years on record in 2014 & 2015 led to water restrictions for all households. https: //anumetservice. wordpress. com/2015/08/17/antigua-is-out-of-surface-water-again/ http: //jamaica-gleaner. com/article/lead-stories/20150807/drought-affecting-lives-across-caribbean http: //www. washingtontimes. com/news/2015/aug/5/parched-caribbean-faces-widespread-drought-waters/? page=all http: //jamaica-gleaner. com/article/lead-stories/20150706/st-thomas-struggles-cope-water-crisis http: //www. jamaicaobserver. com/news/Drought-fuels-bush-fires-in-Manchester
In the news – drought!! 2015: record dry in many places • Belize Potworks Dam in Antigua Millions $ losses in agriculture. • Cuba most severe drought since 2004 with water deficits in 45% of country and 100, 000 people depending on water delivery by tanks. Mona reservoir in Jamaica • Dominican Republic 11% decrease in agricultural production. • Guyana Water Inc. updated water rationing and management practices for Georgetown • Haïti Carraizo reservoir in Puerto Rico 200, 000 families affected by ongoing drought, with a 30% reduction in harvest over 2015 • Puerto Rico streamflows well below average, eastern PR under drought, rationed water supply to San Juan up till October. (PR Met Service) https: //anumetservice. wordpress. com/2015/08/17/antigua-is-out-of-surface-water-again/ http: //jamaica-gleaner. com/article/lead-stories/20150807/drought-affecting-lives-across-caribbean http: //www. washingtontimes. com/news/2015/aug/5/parched-caribbean-faces-widespread-drought-waters/? page=all http: //jamaica-gleaner. com/article/lead-stories/20150706/st-thomas-struggles-cope-water-crisis http: //www. jamaicaobserver. com/news/Drought-fuels-bush-fires-in-Manchester
How do we know? Our drought monitoring products - Standard Precipitation Index (SPI) SPI June to November 2015 • SPI output is an index representing the severity and rarity of wetness (or dryness) of an area • Utilizes only rainfall for computations Source: Caribbean Drought Bulletin Exceptionally Dry Normal Exceptionally Wet most severe usual most severe very rare common very rare
How do we know? Our drought monitoring products - Standard Precipitation Index (SPI) map shows 12 month drought severity between May 2015 and April 2016 Source: Caribbean Drought Bulletin Exceptionally Dry Normal Exceptionally Wet most severe usual most severe very rare common very rare
How do we know? (climatological period 1981 -2010) % of climatological average Below Average
What’s the latest? 2015 -’ 16 Water Year - Canefield (Dominica) rainfall deficit Normal Water Year 2015 -’ 16 Water Year Generated by CAROGEN
What’s the latest? 2015 -’ 16 Water Year - rainfall deficits in the OECS KNA ATG DMA LCA VCT MTQ GRD
Why the ongoing drought? • El Niño is… Since 2015: mostly EL NIÑO Since May-June-July May-June- – Warmer than normal sea surface temperatures across the east-central equatorial Pacific (off the coast of South America). – Due to ocean currents and winds shift near equator. – Occurs every 2 -7 years • El Niño stabilises the atmosphere, tears up storm clouds and leads to dryness in our region… EXCEPT northern Caribbean, where El Niño tends to bring more rains in the dry season. • El Niño 2015 -’ 16, the 2 nd strongest since at least 1950, will end in the May-June-July season. El Niño probably to be replaced by La Niña towards the end of 2016, with opposite impacts (including excessive rainfall and more active hurricane activity) to be expected. •
T Wet/ Hurricane Season R m El Nino/ La Nina p i e n r f Thank You a a Wazita Scott wscott@cimh. edu. bb t l u l Drought e
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