WetHurricane Season 2018 Cari COF Caribbean Climate Outlook

Wet/Hurricane Season 2018 Cari. COF Caribbean Climate Outlook Coordination: Caribbean Institute for Meteorology & Hydrology Dr. Cédric J. Van Meerbeeck - Climatologist Wazita B. Scott – Assistant Climatologist caricof@cimh. edu. bb Participating territories Antigua & Barbuda, Aruba, Bahamas, Barbados, Belize, Cayman Islands, Cuba, Curaçao, Dominican Republic, French Guiana, Grenada, Guadeloupe, Guyana, Haïti, Jamaica, Martinique, Puerto Rico, St. Barth’s, St. Kitts & Nevis, St. Lucia, St. Maarten/St. Martin, St. Vincent & the Grenadines, Suriname, Trinidad & Tobago and the US Virgin Islands

Key Messages 1. Recently: • 2. Current outlook: • • 3. Flooding in Dominica. June to August is not expected to be particularly wet, except for the Guianas, whereas the latter half of the wet season may be wetter than usual over most of the Greater Antilles. Hurricane season activity: Awaiting update later today. Possibly around 12 named storms, 6 hurricanes (2 major). If El Niño returns (chance: around 35 -45%): • September to November drier than usual from the Windward Islands southward; • Hurricane season activity likely weaker. Heat is usually intense between August and October, including heatwaves. Prepare for: Hurricanes. Flash floods. Flooding. Heat stress.

Recently in the news – flooding Source: http: //dominicanewsonline. com) (May 2018) • Dominica experienced flooding in January and May. • Recurrent high winds and swells experienced across the Eastern Caribbean impacting small craft operators. Source: National Works Agency, Jamaica (May 2017)

What’s the latest? Sufficient rain in last 12 months makes drought unlikely in coming months Short-term drought severity by the end of April 2018 Long-term drought severity by the end of April 2018

What’s the latest? Climatological norm This year Last year

What’s the latest? Dec. - April 2018 This year

the exception of Barbados, Grenada, St. Vincent & Grenadines and northern portion of Suriname

What to expect?

ENSO- neutral conditions are present. These conditions are favored through August, with the possibility of El Niño conditions from September. caricof@cimh. edu. bb http: //iri. columbia. edu/our-expertise/climate/forecasts/enso/current/

ENSO and drought in the Caribbean • El Niño, from its onset, stabilises the atmosphere by heating up the upper troposphere in the tropics (increasing odds of a drier wet season in much of the Caribbean). • Towards the latter part of the wet season and during the ensuing dry season, enhanced wind shear tends to tears up storm clouds, decreases tropical cyclone activity and leads to dryness in our region (e. g. 2014 -2016 drought in the Caribbean) EXCEPT northern Caribbean, where El Niño tends to bring more rains in the dry season. • In the year after El Niño’s onset, the wet season tends to start earlier. • La Niña’s are associated with opposite impacts on the Caribbean.

How wet or dry will the next three to six months be? June to August 2018 Drier Usual September to November 2018 Wetter Drier Usual Wetter FORECAST: 1) Usual to drier than usual conditions for the region except for the Guianas from Jun. to Aug. 2) At least as wet as usual from Sept. to Nov. , but possibly drier than usual for Barbados, the Guianas, Trinidad & Tobago and the Windwards.

Verification (Precipitation)

How wet or dry will the next three to six months be in Barbados? June to August 2018 September to November 2018 FORECAST: • Below – normal rainfall amounts across the island for Jun to Aug. • Sep - Nov: At least as wet as usual conditions. IMPLICATIONS: • Possibility of a slower recharge rate of water reservoirs for JJA • Slight decrease in surface and soil moisture for JJA Drier Usual Wetter

Wet days and Wet spell frequency shifts for the next three months JJA 2018 Frequency of wet days What usually happens from June to August? • No. of wet days: roughly 30 to 45 in flatter areas of the islands, and 50 to 65 in mountainous areas and in the Guianas (ABC Is. 5 to 15). • No of wet spells: 3 to 6 (ABC Islands: up to 3), of which 1 to 3 are very wet (ABC Is: up to 2) • No of extreme wet spells: up to 1 or 2. Forecast and Implications: caricof@cimh. edu. bb • Flash flood potential a concern in most areas in the event of extreme wet spells. • Slightly reduced long-term flooding potential and recharge rates of large water reservoirs associated w/slightly fewer wet spells than usual, except in the Guianas. • Less reliable rains for agriculture and slower increase in surface wetness in Belize and the islands

Any Drought concern in the Caribbean? short to midterm drought IMPLICATIONS: long-term drought • No major drought concerns at this point. • Keep monitoring drought at rcc. cimh. edu. bb, as drought concerns might re-emerge if El Niño manifests. Drought alert & action levels

National Drought Outlook Short-term drought situation by the end of August 2018: Forecast: Drought might possibly develop in Christ Church, St. George and St. Phillip. However, major impacts are unlikely. Action level: ü Protect resources and conserve water ü Implement management plans ü Response training ü Monitor and repair infrastructure

Few dry spells – limited risk for June to August 2018 Historical avg. number of 7 -day dry spells What is the FORECAST for June to August 2018? Probability of at least THREE 7 -day dry spells FORECAST: Medium to high chance of at least 3 consecutive 7 day dry spells in Aruba, Belize and much of the Greater Antilles. IMPLICATIONS: • Depending on type of crop, soil moisture for plant water use may be reduced (= crop yield loss). Techniques to conserve top soil moisture may be used. MAX number of 7 -day dry spells

How hot or cool will the next three to six months be? Day time FORECAST: 1) Temperatures from Jun. to Aug. during both night & day are likely to be cooler than in most recent years, except in ABC Islands and Leewards during the day. Jun-Aug 2018 Night time Sep-Nov 2018 Milder Usual Hotter IMPLICATIONS: • It may feel hot at times, but more comfortable than in recent years. • Limited cooling needs in tourism sector than in previous years.

Verification (Temperature)

How hot will the next three to six months be in Barbados? Night time Temperature Day time Temperature FORECAST: • Night and day time temperatures during the hotter part of the year unlikely to be as hot as in recent years. IMPLICATIONS: • Heat discomfort may occur at times, but probably less often than in recent years. Milder Usual Hotter

What does the peak of the hot season look like in the Lesser Antilles, i. e. August to October? 0 7 14 21 USUALLY: around 7 -14 heatwave days over 3 months FORECAST: generally 60 -90% chance for at least 7 heatwave days, and 40 -80% chance for at least 14.

2018 Hurricane Season Forecasts* Forecast Parameter and 1981 -2010 Climatology (in parentheses) CSU 05 th April 2018 Tropical Storm Risk 05 th April 2018 Weather Channel 24 April 2018 Named Storms (NS) (12) 14 12 13 Hurricanes (H) (5. 9) 7 6 6 Intense Hurricanes (IH) (2. 3) 3 2 2 Accumulated Cyclone Energy (ACE) (Median = 100) 130 84 NOAA Climate Prediction Center 24 May 2018 *A separate session at 3 PM focusing on hurricane season will hopefully show an update 22

The Climate Outlook in Summary • For June-July-August: – Heat discomfort at times, especially during heatwaves, but temperatures during this hot part of the year likely a bit cooler than in recent years. – A slower increase in surface & soil moisture than usual is likely, with possibly less reliable rains. – Possibly a reduced recharge rate of water reservoirs and reduced long-term flooding potential, except in the Guianas. – Limited water shortage related problems in agriculture, except where a succession of short dry spells may affect crop growth. – There is potential for flash flooding in the event of extreme wet spells. • For September-October-November 2018: – Heat waves likely in eastern and southern Caribbean, especially in September or October, with cooler temperatures expected from November onwards. – Either wetter than usual or the usual amount of rainfall is likely for the wettest part of the year, with potential for flash floods and long-term flooding. * Stay tuned as we update the information each month!!

Where can we read about this? Our bulletins aim to offer more digestible overviews: Cari. COF Climate Outlook Newsletter Click here Caribbean Coral Reef Watch Click here Caribbean Drought Bulletin Click here

Where can we read about this? Our bulletins aim to offer more digestible overviews: Caribbean Tourism-Climatic Bulletin (since 2017) Caribbean Health-Climatic Bulletin (since 2017) Caribbean Agro-Climatic Bulletin of the Cari. SAM