Precipitation Outlook for the Caribbean and Central America

The Precipitation Outlook for the Caribbean is prepared by the Caribbean Institute for Meteorology and Hydrology with contributions from the regional Meteorological Services and the Climate Research group at UWI, Mona.

The precipitation outlook provides probability distributions indicating the likelihood of below-, near-, or above normal rainfall for the various sub-regions of the Caribbean. For this purpose, ‘normal’ is defined as the climatological mean. The Outlook is generated through analysis of historical records throughout the region, data available from the global climate monitoring system, and computer models of the evolution of the global sea surface temperature field.

The outlook is produced by combining objective input (dynamic model output) and subjective input (experience). The process starts with an examination of the sea surface temperature and precipitation forecasts from the climate models. Currently the output from four climate models are examined; three - ECHAM, CCM3, NCEP - from the International Research Institute for Climate Prediction (IRI) and one from the United Kingdom meteorological Office (UKMO). Tercile probabilities are then estimated for a number of sub-regions based on:

Forecast anomalous precipitation from the IRI models

Probabilities from the UKMO model

The level of agreement between the models

Subjective confidence in the model forecasts based on current conditions in the region and knowledge of the local climatic conditions

Tercile probabilities separate the possible outcomes into three categories – terciles (thirds) - based on the historical precipitation record. The three categories are:

Above normal - wettest third of the record

Near normal - middle third of the record

Below normal - driest third of the record

The tercile probabilities are presented in the form:

A few words of caution. This outlook is relevant only to seasonal time scales and relatively large areas; local variations should be expected, and variations within the 3-month period should also be expected. It is also emphasized that the boundaries between the sub regions are only qualitatively defined, and should be considered as transition zones rather than sharp boundaries. Consequently users of this Outlook are strongly advised to contact their National Meteorological Services for interpretation of this Outlook and for additional guidance.

Disclaimer:

The information contained herein is provided with the understanding that The Caribbean Institute for Meteorology and Hydrology makes no warranties, either expressed or implied, concerning the accuracy, completeness, reliability, or suitability of the Outlook. The information may be used freely by the public with appropriate acknowledgement of its source, but shall not be modified in content and then presented as original material.

Comments -   January  - March 2012

The eastern Caribbean and Guyana are expected to experience above normal rainfall conditions. There is highest certainty is in the region of southern portion of the chain, which includes the Windward and Barbados. The anomalies are also expected to be greater the further south in the chain one goes. The Greater Antilles including Jamaica and Hispaniola should experience normal to above normal conditions, with Cuba most likely experiencing normal rainfall. Belize should experience near-normal rainfall. Further north, The Bahamas is expected to experience below normal rainfall.

ENSO Conditions:

Weak to moderate La Niña conditions are present across the equatorial Pacific. La Niña is expected to continue with weak-to-moderate strength during the northern hemisphere winter (early part of the Caribbean climatological dry season) of 2012, and is likely to dissipate sometime between March and May. Atmospheric circulation anomalies are consistent with La Niña. These developments may have implications for climate conditions in the Caribbean basin.

Caribbean Sea and Ambient Temperatures:

Apart from in the vicinity of The Bahamas, the Caribbean is expected to be dominated by near-normal air temperatures at 2 m for the period January to March 2012. Similarly the Sea Surface Temperatures (SST) will be predominantly near-normal for the period

Precipitation Outlook for Central America from

December to March,2011-12

The weather during the trimester December to February(DJF) is usually characterized as  a cool and rainy period.The months which make up  the trimester(DJF)are often referred to as "transition months." The passage of cold fronts across the country becomes more frequent.When these fronts become stationary,they often produce quite an excess of rainfall.

Climate model forecasts from the International Research Institute(IRI) have  indicated the persistence of a "weak to moderate" La Niña phase.The La Nina has been prevailing since early August.  Probability forecasts for the persistence of La Niña conditions during the trimester October-November-December(OND) and December-January-February(DJF)  range between 69-74%.For the trimester January-February-March(JFM) the probabilities will range near 62%.

Analogous years and number of cold fronts  for  the quatrimester December-March 2011-2012

Seasonal Forecast for Belize(December-March,2011-2012)

Weather systems which can impact on the rainfall for the Caribbean and Central America include upper level troughs or (lows) and cold fronts.The seasonal forecast for Belize and coastal waters is suggesting rainfall will range near normal(denoted in yellow) for  the central and mountainous parts of the country.For coastal areas and the cayes rainfall  amountswill range near normal to above normal.The rainfall distribution will increase gradually from the north to the south.Rainfall amounts will range between  50 to 500m with a mean near 190mm in the north.For central and western Belize rainfall amounts will range between 130 to 750mm with a mean near 370mm.For coastal Belize rainfall amounts will range between 140 to 800mm with a mean near 450mm.For southern Belize rainfall amounts will range between 120  to 1200mm with a mean near 530mm.

Precipitation

The rainfall maps(see below)are an update to the seasonal forecast(for January-February-March 2012) prepared for Belize based on the most recent sea surface temperature(SST) anomalies for October-November-December(OND).These forecasts  indicate  coastal and northern locations for Belize(namely,the International Airport,Melinda,Tower hill and Libertad) will have above normal rainfall.Savannah and Belmopan representing the central and south-central part of Belize will receive near normal rainfall.The remainder of the country(i.e.,the west and south) will likely experience below normal rainfall.)

Prepared by: This e-mail address is being protected from spambots. You need JavaScript enabled to view it . (weather forecaster)