Seasonal forecasting in the Caribbean the process Cedric
Seasonal forecasting in the Caribbean – the process Cedric J. VAN MEERBEECK The Caribbean Institute for Meteorology and Hydrology Cari. COF Forum May, 27 th 2013 Capital Plaza Hotel, Port-of-Spain, Trinidad and Tobago, W. I. 22 -25 May, 2013
RCOFs around the world and the Caribbean Climate Outlook Forum (Cari. COF) Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 2
Climate Prediction (credits: Dr. R. K. Kolli, WMO) Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 3
Cari. COF – time line I • May 1998 – CARICOF meeting – formulate & communicate seasonal rainfall outlook for Caribbean – identify gaps in information & technical capability – facilitate research cooperation & data exchange within/between regions – Improve coordination within climate forecasting community – HOWEVER: outlooks soon left to CIMH… Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 4
Cari. COF – time line I • May 1998 – CARICOF meeting – – – formulate & communicate seasonal rainfall outlook for Caribbean identify gaps in information & technical capability facilitate research cooperation & data exchange within/between regions Improve coordination within climate forecasting community HOWEVER: outlooks soon left to CIMH… • June 2010 – reestablishment of CARICOF – produce a reliable network for provision of consensus rainfall outlooks – train personnel at CIMH and national services in art of seasonal forecasting – enhance relationships with US research institutions in are of seasonal forecasting Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 5
Cari. COF – time line II • February 2012 – Seasonal forecasting workshop – IRI, CIMH & NOAA-NCEP provided 3 -day forecasting training in Barbados to NWS across Caribbean in production of seasonal climate outlooks – technical training in the use of CPT statistical forecasting tool to predict seasonal rainfall – training on exchange of observed rainfall data between national services and CIMH • March 2012 – CARICOF meeting – Consolidation of CARICOF & presentation of actors and stakeholders – presentation of March-April-May CARICOF consensus rainfall outlook – Panel discussions on inclusion of socio-economic sectors in communication of impacts of expected seasonal rainfall Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 6
Cari. COF – successes I • March 2012 - May 2013 – progress in seasonal forecasting – rainfall observation data shared by increasing amount of territories, growing to 23 countries/territories or 132 reliable and representative weather stations – improving familiarity of national weather services with seasonal climate forecasting methods, culminating in 13 territories providing national seasonal outlooks feeding into consensus CARICOF outlook for Sep-Oct-Nov 2012. – active online discussion on improving forecasting methodology to attain international standards, involving 20 territories – since summer, development and roll-out of basic seasonal outlook verification method, with participation increasing from 2 to 9 territories between June and May. – active online discussion arising on further steps and consistent delivery. Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 7
Cari. COF – successes II • Social successes of CARICOF – activation and stimulation of systematic collaboration between national weather services across the English, Spanish, Dutch and French speaking Caribbean territories. – promotion of seasonal climate variability and related possible hazards to national and regional stakeholders. – catalysation of collaborative work and generation of funds towards international collaboration on preparedness through technical training and general assembly. – through collaboration with Central American COF, certain processes were identified to initiate and sustain a workable method for climate impacts reporting. Furthermore, as CARICOF grows to maturity, C A COF and CARICOF will work towards synergetic integration. • NOTE: Status quo = loss of interest only remain successes if momentum is sustained and continuous improvement sought. Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 8
Temperature and rainfall variability in the Caribbean • Temperature and rainfall variability = temporary deviations (or anomalies) from the long-term climatological means. • Seasonal to interannual climate variability tends to be driven by much slower processes than the passage of transient weather systems. Rather, sea surface temperatures (SSTs) exert a significant influence on the state of the atmosphere – especially in the tropics. • SST anomalies at certain locations may alter the seasonal rainfall both in nearby locations as at distant places. • A well known example is El Niño/La Niña, where SST anomalies in the eastern equatorial Pacific profoundly alter convective rainfall locally. However, these anomalies also tend to alter the path of the NH subtropical Jet, the strength of vertical wind shear over the Caribbean and tropical Atlantic SSTs, etc. • Several of the known oscillations – such as Atlantic tropical SSTs, ENSO and NAO – show a certain degree of predictability on seasonal to interannual time scale. Hence, knowing their state may offer usable predictive skill in forecasting air temperature and rainfall sums over the Caribbean. Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 9
Forecast warm North Atlantic and Caribbean Sea SSTs led to forecast of likely normal or above normal MJJ 2013 rainfall for the Lesser Antilles. El Niño region Caribbean & tropical Atlantic
During El Niño, autumn and winter rainfall are usually enhanced over the Bahamas, but reduced over the Lesser Antilles and the Guianas. La Niña tends to result in the opposite rainfall gradient. E. Caribbean: ’ 09 -’ 10 El Niño - record dry; ‘ 10 -’ 11 La Niña - record wet. NOAA CPC – ENSO monitoring EL NINO LA NINA
NOAA CPC – NAO monitoring March to half-April were particularly dry in the Lesser Antilles, exacerbating drought conditions in the region. Recent research suggests that transitions from a positive to a negative North Atlantic Oscillation (NAO) phase may be accompanied by enhanced forecasting skill of seasonal rainfall in the Caribbean (Bedward and Van Meerbeeck, 2013). è NAO conditions incorporated in Cari. COF rainfall outlooks since March 2013.
Cari. COF consensus seasonal climate outlooks Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 13
How do we do it? – general methodology I Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 14
How do we do it? – general methodology II Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 15
How do we do it? – general methodology III Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 16
Cari. COF CPT output (black) and National/sub-regional MJJ rainfall outlooks (gray) May – June – July 2013
How do we do it? – general methodology IV Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 18
How do we do it? – Seasonal rainfall outlook maps • The Cari. COF seasonal rainfall outlook maps present three-monthly tercile probability forecasts generalised over areas within the Caribbean. • The forecast terciles: – above normal rainfall (A) – predicted seasonal rainfall sum will fall within the (wet) category of the top 33% highest sums from all years in the climate record; – normal rainfall (N) – predicted seasonal rainfall sum will not fall within ( the category of either the top 33% highest or lowest sums from all years in the climate record; – below normal rainfall (B) – predicted seasonal rainfall sum will fall within the (dry) category of the top 33% lowest sums from all years in the climate record. Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 19
How do we do it? – Seasonal rainfall outlook maps Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 20
The Cari. COF JJA climate outlook EGU GA 2013 - Vienna Austria 21
Cari. COF – what lies ahead? • Further training of forecasters is required for the Cari. COF forecasting process to attain maturity: – technical training on verification of forecasts last week; – technical training on forecasting methods (e. g. composite analysis, analogues) 2014/2015; – technical training on forecast applications to specific situations (e. g. SPI forecasting for drought/excessive rainfall) 2013/2014; – training on efficient communication of forecasts to stakeholders this week, 2013/2014/2015; – training on the use of media to effectively communicate forecasts this week, 2013/2014/2015. • Note that training should be an iterative process. A tool once learned will only be used in case of frequent practice, and forecasting skills will only improve through regular communication on methods and updates. Cari. COF seasonal forecast verification training workshop – Trinidad 22 -05 -2013 22
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