TABLE OFCONTENTS Page
Table of contents 2
Editorial 3
Preface 4
1.0 Synoptic Review 4
1.1 The Inter-Tropical Discontinuity (ITD) 4
1.2 July 5
1.3 August 6
1.3.1 Quarterly Rainfall distribution 6
1.3.2 Maximum temperature maps 7
1.4 September 7
1.4.1 Minimum temperature maps 8
2.0 Seas Surface Temperature Analysis 8
2.1 Maps of Sea Surface Temperature 9
3.0 Sample of Daily Marine Weather Forecast 11-14
EDITORIAL
The quarterly marine meteorological bulletin is published by NiMet every quarter of the year namely January – March, April – June, July – September, and October – December. The bulletin provides useful weather and climate information for coastal dwellers as well as users within the maritime/ oil and gas sector of the Nigerian economy.
Publisher
Prof. Sani Abubakar Mashi
Director- General/CEO
Nigerian Meteorological Agency (NiMet)
Chief Editor
Mr. Joseph. E. Alozie
Ag. Director/ Applied Meteorological Services
Associate Editor
Mrs. Glory Onyegbule (Asst. General Manager/ Marinemet Services)
Contributing Authors
Mr. Sunday Aribisala - Senior Met/Marinemet services
Mrs. Wahidat Mustapha Met I/Hydromet services
Cover pictures Ship, buoy & map of the coastal part of Nigeria
Corporate Address
The Director General / CEO
Nigerian Meteorological Agency (NiMet)
National Weather Forecasting & Climate Research Centre
Nnamdi Azikiwe International Airport
Abuja Nigeria
Email:
Website: www.nimet.gov.ng
No part of this publication may be reproduced by any means without written permission from the publisher.
Preface
The coastal area of Nigeria is one of the areas worst hit by the vagaries of weather as well as host to the revenue base of the country- the oil and gas industry. There is therefore need for in-depth analysis of the weather and climate of the marine environment to service the user community including the maritime, oil and gas, coastal recreation, fishermen, the academia, and the general public. The quarterly marine met bulletin meets this need.
The Nigerian Meteorological Agency (NiMet) has produced this third edition of the 2016 Quarterly Marine Meteorological Bulletin (July – September, 2016)in line with the Agency’s mandate to provide marine weather services for the maritime sector with a view to improving efficiency and safety of operations in and near the Nigerian coast. The marine weather stations from which the bulletin source its data are located at East mole Lagos, Nigerian Institute of Oceanography and Marine Research (NIOMR) Lagos, Eket in Akwa Ibom State, Koko in Delta State, Aiyetoro in Ondo State, Onne Port in Rivers State, and Calabar marine station in Cross- River State. The bulletin details marine meteorological and oceanographic information such as the synoptic review comprising the ITD, and the marine weather features during July, August, and September, 2016. It also contains information on the temperature trend as well as the sea-state forecasts for marine users both at sea and along the coast. They also serve as useful guides for enhanced productivity in the maritime industry.
1.0 Synoptic Review
The Nigerian coastline lies between Latitude4° 10’ to 6° 2’ N and Longitude 2° 45’ to 8° 35’ E spanning about 853km of low-lying coast. The coast is bordered by a narrow continental shelf of the Gulf of Guinea, shelf widths range from 15km in the West to about 67km in the Niger Delta and about 87km off the Cross River estuary in the East. The Nigerian coastal zone comprises of Lagos, Ondo, Delta, Rivers, Bayelsa, Akwa Ibom and Cross River States and parts of Edo State where an estimated 25 percent of the population of the country live. There are high economic activities within Ports, harbor and major maritime and oil and gas industries in the coastal area. This section discusses the ITD and key marine synoptic features during the period under review.
1.1 The Inter-Tropical Discontinuity (ITD)
Figure 1 shows the variation of the Inter-Tropical Discontinuity (ITD) during the 3rdquarter of 2016. As expected, the ITD continued in its northward movement, with a peak value of 23.50N in the 3rd dekad of July. Its position ranged from 16.7 – 20.90N and 13.9 – 18.5 0N in August and September respectively. By this position, the coastal zone of the country came under zone D weather condition giving rise to rainfall of continuous nature. The monthly details of the synoptic situation during the 3rd quarter of the year are given below.
1.2 July
In July, the Inter-Tropical Discontinuity (ITD) position fluctuated between latitudes16.0°N and 23.5°N, and indeed reached its northernmost position of 23.50N on July 18 2016 (fig. 1). The ITD actually commenced its southward movement thereafter, indicating that the peak of the ITD was reached earlier than normal by one month in 2016.The winds were predominantly southwesterly, occasionally backing southeasterly with speed ranging from 5 - 15kts, occasionally reaching a high of18kts. The mean daily maximum temperatures ranged from 24.6°C - 31.9°Cwhile the mean minimum temperatures ranged from15.00C- 27.80C. The average Sea Surface Temperature (SST)was between23.9°C and 28.90C.The coastal Mean Sea Level Pressure (MSLP) values fluctuated between 1010 - 1013hPa, occasionally filling up to 1015hPawhile the center value of St. Helena high pressure was between1022hPa and1038hPa during the month.
Fig 1: Analysis of ITD position in the 3rd quarter of 2016
Most parts of the coastal area experienced intense rainfall activities as the period marked the peak of the rainy season especially around the coastal area of Nigeria. Rainfall amounts recorded in the various stations were 77.1 mm at Calabar, 199.9mm at Eket, 87mm at East mole, 91.2mm at Koko, 82.2mm at Onne, and 62.8mm at Aiyetoro station. There were no records of disruption of activities due to adverse weather at the ports and coastal areas in July. Minimum (night time temperature) was coldest around Aiyetoro -Ondo State with a value of 15.00C while the maximum (day-time temperature) was warmest around Calabar – Cross River State with a value of 31.90C.
1.3 August
In August, the ITD continued on a movement, fluctuating between latitudes 20.90N and 16.70N.South Westerly winds continued to dominate the coast with average speed of between5-15kts, occasionally reaching17kts.The St. Helena high pressure cell fluctuated between1021hPa -1035hPa. The highest maximum temperature was (33.40C) over the southeast coast of Onne while the lowest was at East Mole, Lagos (280C). However, the average daily mean maximum and minimum temperatures ranged between 27.0°C -29.3°C and 17.5°C- 24.3°C respectively around the coastal belt. Highest day time temperature for the month was observed over Onne in Rivers State (33.40C) with the least minimum temperature recorded over NIOMR Lagos State (24.40C).
Observed average Sea Surface Temperature (SST)over Eket, East mole, and Koko were 26.6°C, 26.1°C and 27.00Crespectively. Monthly rainfall amounts recorded over Calabar, Eket, East Mole, NIOMR, Koko, Aiyetoro and Onne stood at 364.6mm, 629.8mm, 241.7mm,241.7mm, 221.1mm, 163.0mm, and 475.0mm of rainfall respectively. The relatively lower rainfall amount in the south west was as a result of the pronounced Little Dry Season (LDS) experienced over the area during the month of August. The sea state remained slight to moderate with occasional rough condition.
1.3.1
S/N / Station / Rainfall amount(mm)July / August / September
1. / Calabar Marine / 77.1 / 364.6 / 345.3
2. / Eket / 199.9 / 629.8 / 738.1
3. / East Mole / 87 / 241.7 / 210.6
4. / NIOMR / 87 / 241.7 / 210.6
5. / Koko / 91.2 / 221.1 / 531.7
6. / Aiyetoro / 62.8 / 163.0 / 585.5
7. / Onne / 82.2 / 475.0 / 233.8
Table 1: Rainfall distribution along the coast in the 3rd quarter of 2016
Fig 2a– 2d: Map showing the mean maximum temperatures over the coast during the third quarter 2016.
1.4 September
In September, the Inter Tropical Discontinuity (ITD) line continued its northward incursion and gradually began a southward descent, fluctuating between Lat. 13.9°N, and18.5°N with a mean position of 16.4°Nleading to a remarkable increase in moisture influx, especially around the south eastern coast. Generally, the winds were South Westerly backing southerly, with speed ranging 5-18knots. There was a slight increase in mean daily maximum and minimum temperature along the coast line of Nigeria as compared with the month of August with observed mean values between 27.20C-29.70Cand 17.4oC-24.60C respectively. Daily mean Sea Surface Temperature (SST) dipped remarkably over Eket, East mole and Koko with mean values of 26.9oC, 27.30C and 27.5oC respectively. The month also witnessed further intensification of the St. Helena high pressure system from1025hPa to 1044hPa bringing in more moisture into the country leading to increased rainfall amounts recorded for most parts of the coast during the period.
There was a marked increase in rainfall amount in the month of September over the south west part of the coast as the month marked the second peak of the season for that region. Eket recorded the highest amount of about738.1mm while Aiyetoro, Koko, East mole, NIOMR, Onne, and Calabar recorded 585.5mm, 531.7mm, 210.6mm, 217.8, 233.8mm and 345.3mm of rainfall respectively. The sea state was predominantly slight to moderate. The highest maximum temperature was observed at NIOMR Lagos State with a value of 33.2oC while the lowest minimum of 24.7oCoccurred at Aiyetoro in September, 2016.There were reports of disruption of activities due to coastal flooding along the coast of Lagos, Rivers, and Akwa Ibom States in the months of August and September.
Fig 3a – 3d: Map showing mean minimum temperatures over the coast during the third quarter of2016.
2.0 The Sea Surface Temperature (SST) Analysis
The variation of Sea Surface Temperature (SST) over Eket, East Mole and Koko is shown in Figures 4a, 4b and 4c for the third quarter of 2016. There was a decreasing trend in Sea Surface Temperature during the quarter under review. However, the coastal waters were warmer during the first 10 days of July
Fig 4a: Variation of SST over Eket(July – September, 2016)
Fig 4b: Variation of SST over East Mole, Victoria Island, Lagos (July – September, 2016)
Fig 4c: Variation of SST over Koko (July – September, 2016)
3.0
SAMPLE DAILY MARINE FORECAST DURING THE QUARTER
NIGERIAN METEOROLOGICAL AGENCY (NIMET),
NATIONAL WEATHER FORECASTING AND CLIMATE RESEARCH CENTRE,
NNAMDI AZIKWE INTERNATIONAL AIRPORT, P.M.B. 615, GARKI, ABUJA, NIGERIA
FORECAST FOR INSHORE WATERS OF NIGERIA up to 20km offshore (60 13'N, 2054'E to 40 32'N, 80 23'E)
at 1500 UTC Wed. 29th June, 2016.
Period of Forecast: 1800 UTC Tue. 6th to 1800 UTC Wed., 7th Sept., 2016.
WARNING: Nil
General Situation: Over the forecast area an influence of a low pressure system is expected to remain and fluctuating between values 1013 - 1014hPa at about 1800 UTC. It is expected to give way to a ridging effect and fill up to 1015 – 1016hPa from about 2100 UTC, thereafter weaken to its initial values at about 1500 UTC and remains quasi stationary till the end of forecast period. Convective activities are expected with light to moderate occasionally fresh breeze.
Calabar, Eket and Port Harcourt coastal waters
24 Hour forecast
Wind: South westerly veering westerly, 5 – 10kts occasionally 16kts.
Sea state: Small waves, becoming longer; fairly frequent white horses (Moderate)
Tide: Cal – high: 2.8m (0835 UTC), low: 0.8m (0240 & 1515 UTC)
PHC–high: 2.2m (0900 UTC), low: 0.4m (0210 & 1450 UTC)
Weather: Chances of rain/thunderstorm.
Visibility: Moderate (4 -10km).
Outlook for the following 24hrs:
Wind: South westerly, 5 – 10kts occasionally 18kts
Sea State: Small waves, becoming longer; fairly frequent white horses(Moderate)
Weather: Rain, chances of thunderstorm.
Visibility: Moderate (4 -10km).
Warri, Koko and Aiyetoro coastal waters
24 Hour forecast
Wind: South westerly, 5 – 10kts occasionally 15kts
Sea State: Small waves, becoming longer; fairly frequent white horses (Moderate)
Tide: Warri – high: 1.7m (1105 UTC), low: 0.7m (0425 & 1700 UTC)
Weather: Fair, chances of rain later.
Visibility: Moderate (4 -10km).
Outlook for the following 24hrs
Wind: South westerly, 5 -10kts occasionally 16kts.
Sea State: Small waves, becoming longer; fairly frequent white horses(Moderate)
Weather: Fair, rain/thunderstorm later.
Visibility: Moderate (4 -10km).
Lagos Coastal Waters
24 Hour forecast:
Wind: South westerly veering westerly, 5 – 12kts
Sea State: Small waves, becoming longer; fairly frequent white horses (Moderate)
Tide: High: 0.8m (0715 UTC), low: 0.1m (0055 & 1335 UTC)
Weather: Fair, chances of isolated rain later.
Visibility: Moderate (4 -10km).
Outlook for the following 24hrs
Wind: South westerly, 5- 10kts occasionally 15kts.
Sea State: Small waves, becoming longer; fairly frequent white horses(Moderate)
Weather: Fair, rain with chances of thunderstorm later.
Visibility: Moderate (4 -10km).
End.
SHIPPING FORECAST TO 650KM OFFSHORE (60 13'N, 20 54'E - 40 32'N, 8023'E to equator)
ISSUED BY NIGERIAN METEOROLOGICAL AGENCY (NIMET),
at 1500 UTC on Tue. 6th Sept., 2016
VALID FOR: 1800 UTC on Tue. 6thto 1800 UTC Wed. 7th Sept., 2016.
WARNING: NIL
GENERAL SYNOPSIS: St Helena’s high pressure system is expected to weaken from 1035hPa where it was yesterday to 1030hPa at about 1800 UTC and expected to remain quasi stationary till the end of forecast period. The offshore area is expected to experience a low pressure system ranging from 1014 - 1015hPa. At about 2100 UTC it is expected fill up and gives way to a ridge of 1016 - 1018hPa. The system is expected to relax and deepen to its initial values at about 1500 UTC and remain till the end of forecast period. Light to moderate breeze are expected.
THE AREA FORECAST FOR THE NEXT 24 HOURS
WIND: South westerly, 05– 10kts occasionally 16kts
SEA STATE: Small waves, becoming longer; fairly frequent white horses (Moderate)
WEATHER: Fair, chances of rain later.
Visibility: Moderate (4 -10km).
END.
Graphics on wave heights or sea state
The graphics below are the base and projections of the wave height for 00hr, 12hr, 24hr, 36hr during the forecast period.
NiMet
Headquarters Abuja
Date: November, 2016.
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