Date of Issue: October 30th, 2021
ØSeasonal Forecast: November 2021 to January 2022 (NDJ)
Rainfall
The wet/ hurricane season ends officially on November 30th. The month of December is considered a transition month into the dry season and conditions vary from year to year. While a gradual reduction in rainfall totals is expected as the island moves through the dry season which is from December to May, with La Niña now in place, wetter than usual conditions are forecast for the season November 2021 to January 2022. A slight increase in the frequency of wet days and wet spells from the normal is expected. At most 2 extremely wet spells are possible and this could result in flash flooding and other related hazards. There is a very low chance of having at most one 7-day dry spell during the season.
Temperature
The island is now moving into its cool season and a general decrease in temperature is expected. However, temperatures are expected to be slightly warmer than usual. Cooler temperatures may occur especially during rainfall events.
ØInfluencing Factors
1. El Niño Southern Oscillation (ENSO)
Recent observations: La Niña, the cool phase of the El Niño-Southern Oscillation climate pattern has returned to the tropical Pacific this month and there's an 87% chance it will last through to February 2022. Sea Surface Temperatures (SSTs) in the eastern Pacific have recently cooled to about -0.6°C.
Model forecast and guidance: The Niño-3.4 SST index favours La Niña to continue through the first half of the 2021/ 2022 dry season. ENSO-neutral conditions are predicted to return during March-May 2022.
Expected impacts on rainfall: La Niña tilts the odds to more rainfall activity in November-December-January across the lesser Antilles.
2. Climate conditions in the Tropical North Atlantic (TNA) and the Caribbean Sea
Recent observations: SSTs have warmed to 0.5-1°C above average around the Caribbean and in equatorial sub-tropical portions of the Tropical North Atlantic (TNA).
Expected conditions: Models are expecting SSTs to maintain anomalously warm (0-1°C above average) temperatures across the Caribbean Sea and the TNA
Expected impacts: Warm SSTs in and around the Caribbean tend to contribute to higher air temperatures with above-average humidity, seasonal rainfall totals and an increased frequency of extreme rainfall.
See table below with Climatological Normal/ Averages
November-December-January Season CLIMATOLOGICAL NORMAL (30YEARS) |
||
RAINFALL |
CANEFIELD AIRPORT |
DOUGLAS-CHARLES AIRPORT |
Normal |
255.8 to 528.3mm |
493.9 to 746.8mm |
Wet Days Normal |
41 to 53 days |
55 to 66 days |
7-Day Dry Spells Normal |
n/a |
0 to 1 |
TEMPERATURE (15YRS AVERAGES) |
||
Average Maximum |
30.3°C to 30.7°C |
29.0°C to 29.2°C |
Average Mean |
26.3°C to 26.6°C |
25.8°C to 26.1°C |
Average Minimum |
22.3°C to 22.7°C |
22.6°C to 23.1°C |