Updated Cyclone Monitoring
As we enter the new cyclone season for the South Indian Ocean, we takethis opportunity to announce that we are in the final stages of developing an improved warning dissemination system. Over the past several years our focus has, essentially, been on retransmitting the official text warnings issued from Reunion Island and the Joint Typhoon Warning Center (JTWC). For non-meteorologists these bulletins can bemore confusing than illuminating with considerable jargon included. For this season we are initiating a daily graphic based on the JTWC information. This graphic will depict previous path, strength and forecasts for cyclones that pass 90E. This will be done once-per-dayand will portray all active systems in a color-coded strength. If landfall over Africa is predicted then the frequency of issuance will be increased. As this information is coupled with the available NOAA 20 km resolution forecast model data and the USGS hydrological models, we should achieve a considerable increase in our capability to predict possible impacts.
With respect to the general weather over Africa, with the continued southward migration of the ITCZ, heavy rainfall fell over the region from western Liberia eastward to Cameroon with rainfall amounts exceeding 75 mm in some areas. This rainfall extended into Equatorial Guinea, Gabon, northern Congo, central Democratic Republic of the Congo and central to eastern Central African republic. The heavy rain along the Cameroon-Nigerian border continues the flooding region depicted during the past several hazard periods.
In southern Africa, local rainfall amounts up to 75 mm were around observed over northern Angola. Lesser amounts of up to 15 mm were observed over central Namibia, South Africa and Lesotho.
Finally, in northern Africa, rains up to about 20 mm, locally, fell inMorocco with lesser amounts in Algeria and Tunisia.
AFRICA WEATHER HAZARDS ASSESSMENT EXPLANATION
VALID October 9-15, 2003
1) Heavy rains fell over portions of southern Nigeria and western Cameroon during the last week, with 7-day accumulations exceeding 150 mm locally. This trend is forecast to continue thru the next period, though heavy rainfall is normal at this time and these locations. Flooding remains a concern though due to saturated soils and high river levels, especially along stream banks and in urban centers that experience heavier storms during the period.
2) Long term drought continues in parts of northern Somalia, including the towns of Garoowe, Qardho, and Laas Dawaco. September saw virtually no rainfall in the area, and October remains dry as well, though October should normally yield from 10-50 mm of rainfall for the month. Precipitation forecasts do not show any rainfall accumulations in the area during the next week.
3) Much of the area in southern Ethiopia experiencing dry conditions for the year received from 25-100 mm rainfall during the month of September, though normal totals should be closer to 50-200 mm. Weekly rainfall totals from the past 7-days reached 20 mm in the region, and similar rains are likely during the next week. These lighter than normal rainfall amounts do not spell an end to the dryness in the near future.
4) Local flooding concerns continue in parts of western Kenya in the region adjacent to northeastern Lake Victoria. Although widespread flooding is not likely, locally heavy thunderstorms during the next week may produce sufficient rainfall to cause some problems. Rains have generally been heavier than normal since early September.
5) The coastal region extending from southeastern Kenya near the city of Malindi to northeastern Tanzania near Dar es Salaam has received much less than normal rainfall since September, and short term dryness is becoming a concern. Though little to no rain fell during September, monthly totals should have been on the order of around 20-60 mm. Current atmospheric conditions to not bode well for the formation of accumulating rainfall during the next week, and thus the area should remain dry.
6) Though much of the drought affected area of southern Mozambique and eastern South Africa received little to no precipitation during the last week, an area of rainfall with 7-day totals near 40 mm was seen near Swaziland. Additional relief is probable during the next week, as a cold frontal system should bring moderately heavy rains to much of the area, especially near the coast.
7) Seasonal dryness currently in and around Lesotho did not receive much relief during the past week, though light to moderate rains may fall in the region during the next week. Conditions seem to be improving somewhat in the area and the current weather pattern is trending toward a wet next few weeks.
8) A Strong spring cold front may bring severe weather, heavy rains, and mountain snows to part of southeastern South Africa, mainly from October 11-14. While rains may benefit some areas experiencing seasonal dryness, other areas may see some local flooding and possibly heavy snowfall if the system intensifies as forecast. Colder than normal temperatures may set into the area after the front passes through, further causing problems.
Timothy B. Love