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Please consider this to be a VERY developmental product.
Due to the increased relative importance of the eastern
region, the calculated rain line location plot for November-March
will summarize the line from 10W-35E.
The Intertropical Discontinuity/Intertropical Front
From the African Desk, Climate Prediction Center, NOAA
October 21-31 2004 - During the current period, the overall longitude averaged ITCZ was located near 11.8 degrees north latitude compared to the long term mean of 12.6N and a previous location of near 12.4N. This marks another consecutive period that the overall position has exhibited a southward bias compared to normal. Examining the west from 10W-10E, the recent ITCZ position was located near 12.4N compared with the 1988-2003 average of 13.2N. The east (from 20E-35E longitude) saw an ITCZ placed at around 11.6N, collocated with the long term mean position. Overall, the largest southward bias continues to be seen near the Senegal/Mali border region, though continued light showers have been seen throughout the area during the past month.
October 11-20 2004 - The African ITCZ continued its southward progression toward the equator, with the only stationary movement near the Senegal/Mali region. This period, virtually the entire Africa region of the ITCZ was located south of its climatological position, with the current location collocated well with the northern extent of ten-day precipitation. For the record, the latest analysis places the average 15W-25E ITCZ near 12.4 degrees north latitude, compared to last period's location near 14.0N and the long term mean position of around 14.0N. From period to period, the average ITCZ during this time of year progresses around 1.2 degrees south, while the recent movement was closer to 1.6 degrees southward. Examining precipitation, dryness continued to set in throughout much of the Sahel, except near southern Mali which experienced light to moderate showers. The ITCZ in this region (10W-10E) is currently located near 13.0N, compared with the long term average of 14.7N. In the east, while northern Somalia dried out, significant precipitation was seen in much of southern Ethiopia, southern Somalia, and eastern Kenya, with localized flooding reported. The ITCZ from 20-35E is currently located near 12.0N compared with the climatological position of around 13.1N.
October 1-10 2004 - The African portion of the Intertropical Convergence Zone was located near 14.0 degrees north latitude, compared with the 1988-2003 mean location of 15.2N. This current location is around a degree southward from the position during late September and also around a degree south of the October 1-10 2003 average position. Compared to last period, rainfall increased in much of Guinea Bissau, coastal Gulf of Guinea, Cameroon, Gabon, and eastern Ethiopia. Precipitation decreased in parts of northern Senegal, southern Mali, southern Sudan, and western Kenya. The current western (10W-10E) ITCZ location (14.6N) is around 1.3 degrees south of normal. The ITCZ in this area has been retreating southward at a near climatological rate since the end of August. In the east, from 20E-35E, the current location (13.7N) is around 0.4 degrees south of the 1988-2003 mean.
September 21-30 2004 - The African portion of the Intertropical Convergence Zone was located near 15.0 degrees north latitude, compared with the 1988-2003 long term mean of 16.0N and last period's position near 15.2N. Overall, the ITCZ moved very little from mid-month, though it did recess in southern Mauritania and eastern Senegal. Rains were generally near normal during the period, though some extreme amounts were seen near the southern Nigeria/Cameroon border region. The western portion of the ITCZ, seen in figure 2, is located near 15.8N compared with the long term mean position of 16.7N. The eastern region is closer to normal and is currently located near 14.2N.
September 11-20 2004 - The African region of the Intertropical Convergence Zone was located near 15.2 degrees north latitude, compared with the 1988-2003 mean of 17.0N and a previous position of near 16.3N. The current ITCZ location is very close to the maximum northward extent of current rainfall. The entire longitude of ITCZ is currently southward of its normal position, though areas to the west appear slightly more displaced than in eastern areas. Examining the west averaged from 10W-10E, the ITCZ is currently located near 16.2N, compared to last period's 17.6N and the normal of 17.8N. The east (20-35E) is currently located near 14.1N, while the normal location is 15.6N and last period saw the average near 14.9N. The ITCZ is now progressing to the south at a near normal rate, though the actual location is south of normal, especially near Chad and Sudan.
September 1-10 2004 - The African region of the Intertropical Convergence Zone was located near 16.3 degrees north latitude when averaged from 15W-35E. Virtually the entire ITCZ is currently south of the long term mean position and the western region moved significantly southward from the previous period. In fact, the movement in the 10W-10E region was around 1.6 degrees south during the period, while the east from 20-35E moved very little during the past ten days. For the 2004 season, it is apparent that the maximum northward location of the ITCZ in the west occurred about twenty days early during the last ten days of July, while the west saw a temporally normal but northward biased peak during mid August.
August 21-31 2004 - The African portion of the ITCZ moved dramatically to the south in the eastern half of the continent as the eastern region of the ITCZ moved from around 19N to around 15N. This contrasts the movement in the west, where the ITCZ moved relatively little from last period and is located very close to the 1988-2003 climatological mean. The longitude-averaged location during the recent period was near 17.4N compared to the normal of near 18.2N and last period of near 19.2N. The ITCZ should be and appears to be retrograding to the south, as the normal northward peak occurs during mid August.
August 11-20 2004 - The longitude-averaged African portion of the ITCZ was located near 19.2 degrees north latitude, compared to last period's position of 17.6 degrees north latitude and the 1988-2003 mean position of 18.5 degrees north latitude. The ITCZ reaches its climatological northern-most position during the August 11-20 period. Weak low pressure areas over central Mauritainia and central Mali helped to lift the ITCZ northward over the western Sahel, while southerly winds helped to push the ITCZ northward over Sudan and Chad.
August 1-10 2004 - The longitude-averaged African portion of the ITCZ was located near 17.6 degrees north latitude, compared to last period's position of 18.5 degrees north latitude and the 1988-2003 mean position of 18.4 degrees north latitude. Northerly winds blew across Mauritainia and northern Mali, pushing the ITCZ southward in the western Sahel. These winds resulted in a dramatic southward shift of the ITCZ of 3 to 4 degrees latitude over Mauritainia and central Mali. Further east, southerly winds helped to lift the ITCZ northward to more seasonable latitudes across Chad and Sudan. The average position of the ITCZ over central Niger was more or less unchanged and remains close to its climatological position.
July 21-31 2004 - The longitude-averaged African portion of the ITCZ was located near 18.5 degrees north latitude, compared to last period's position of 18.3 and the 1988-2003 mean of 18.3N. Again nearly stationary compared to the previous period, the ITCZ was influenced by a strong low pressure system located over the western Sahara Desert. This brought strong southerly winds and increased moisture to areas east of Mali and somewhat stronger than normal northerly winds westward to the Atlantic coast. Much of the period saw unusually strong northerly winds blowing dry air and warmer temperatures from The Mediterranean through eastern Libya and Egypt into Chad and Sudan. The western area of the ITCZ continued moving north during the period and was located near 20.7N compared to a normal position of 19.3N. Also unusual were conditions in the east. From the eastern analysis, it is seen that the current ITCZ position was near 15.5N, compared to normal of 16.7N. The ITCZ actually moved 1.3 degrees south from the previous period!
July 11-20 2004 - The African ITCZ moved northward at a near climatological rate in the east, while the west was nearly stationary. Overall from 20W-35E, the latest ITCZ position was approximately 18.3N compared to a 1988-2003 normal of 17.4N and a 2003 location of near 18.5N. The longitude-averaged location moved around a half degree north from its position during the first ten days of July. Associated with the current position, precipitation increased throughout much of southern and central Mali, central Niger, central Sudan, and much of Uganda. Alternatively, rainfall decreased near Lake Volta, much of CAR, and in southern Ethiopia. In the west (10W-10E), the current ITCZ was located near 19.7N, a meager 0.3N from last period, and 1.3N of its climatologically-normal position. The east (20E-35E) saw much more normal progression northward (around 0.9 degrees north from last period), and the region's ITCZ was located around 0.8 degrees north of normal. Influencing the ITCZ during the recent period was a particularly strong surface low pressure region in eastern Mali on July 14th which brought increased rains to central Niger and correspondingly increased northerly winds (and a suppressed ITCZ) to the west. A strong easterly wave pushed into Mali on the 17th, influencing the ITCZ in the area.
July 1-10 2004 - The African portion of the ITCZ continued to move significantly northward from its position during the final ten days of June. For the period, the average location was near 17.8N, compared to last period's position near 16.3N, last year's position of 17.9N and the 1988-2003 climatological normal of 16.5N. Contributing to the strong northward bias in the west was a stronger-than-normal surface low pressure area near northern Mali and Western Mauritania which brought moderate southerly winds into the region and pushed the ITCZ northward. Northerly winds on the western side of the low were checked in that they influenced the ITCZ somewhat less than normal. Examining the western region from 10W-10E, the average position moved more than two degrees north from the previous period and is located near 19.4N. In the east from 20-35E, the ITCZ moved little from last period and is located near 15.9N.
June 21-30 2004 - The overall longitude-averaged position of the Africa ITCZ surged northward, especially in the east, and was located near 16.3 north latitude. The latest position is around 1.4 degrees north from its location during the second ten days of June, though the 2003 position during the current period was closer to 16.9N. This strong northward movement is not normally seen during the north-to-south progression of the ITCZ, though it resembles its retreat in September or October. The contribution of this northward jump was mainly from the east as opposed to western longitudes. For the record, the western (10W-10E) area of the ITCZ was located near 17.0N as opposed to the climatological mean of 16.8N. The eastern (20-35N) area's current and mean positions were 15.9 and 14.2 north, respectively. Associated with the latest movement, increased rains were seen in southern Senegal, central Mali, and southern Chad during the last period, while dryness was seen along parts of Côte d'Ivoire.
June 11-20 2004 - The African portion of the ITCZ moved around 0.3 degrees north from the average position during the first ten days of June. This places the longitude-averaged location near 14.9N compared to the 1988-2003 mean of 15.2N and the 2003 value of 15.3N. Significant factors contributing to the mean position were a strong cold front passing through northern Algeria on June 14-17, generally normal easterly wave movement throughout the period, a weak MJO pattern, and strong northerly winds blowing through Mauritania into Senegal and western Mali. In the central and eastern regions, the current position is very close to the long term normal, though a southern bias exists in the extreme west and a northern bias is seen over eastern Mali and western Niger. Precipitation during the period was overall less than normal in the west except in and around Burkina, and substantial relative dryness was seen in eastern Sudan and western Ethiopia. The past year's progression of the ITCZ in the west and east, respectively show that each zone continues to see a near normal ITCZ position (west:16.3N current; 16.2N mean) (east:13.7N current; 13.9 mean) and movement northward continues at a steady rate.
June 1-10 2004 - The African ITCZ moved about half a degree north from the previous period, and was located near 14.6 degrees north latitude compared to a 1988-2003 normal location of around 14.8 north. Overall since the beginning of April, the ITCZ has been very near its climatological position and has only deviated on a daily time scale. Compared to 2003, this overall longitude-averaged ITCZ is currently located about 0.6 degrees south of its position last year, and it has seen a much more constant rate of northward movement. Compared to the last ten days of May, precipitation increased throughout much of western Africa, but especially along coastal Gulf of Guinea areas, southern Mali, and Burkina. From 10W-10E longitude, the ITCZ moved strongly northward from 5 degrees E to the coast of Senegal. This would partially explain the increased moisture throughout this area. In the east, the ITCZ moved very little when averaged throughout the period.
May 21-31 2004 - The African portion of the ITCZ moved approximately 0.6 degrees northward and was located near 14.1 degrees north latitude. This overall position from 15W-35E is very close to the 1988-2003 climatological mean. Throughout the period, strong northerly winds from northern Africa kept the ITCZ in check over the Senegal area, though regional pressure influences allowed the convergence zone to creep more northward than has occurred during the past few months. The effects of this northward movement could be seen where an area of precipitation was observed over southern Senegal for the first time this season. This rainfall may be associated with lesser precipitation to the south along coastal Liberia and Côte d'Ivoire. From 10W-10E and the eastern region from 20-35E, the ITCZ is steadily moving northward and is very close to the long-term mean position.
May 11-20 2004 - The African ITCZ from 15W-35E was located near 13.5 degrees north latitude when averaged over the period. This was very close to its long term mean position and much (~1.3degrees) to the north from the previous period. The largest northward movement occurred near Niger and Burkina. Rainfall associated with this bulge was seen to fall along and south of the area. Elsewhere, rainfall was heavier than last period in much of the western Sahel, CAR, Chad, and Sudan. In the west from 10W-10E, the average position of the ITCZ was near 15 degrees north, compared to a mean of 14.7N and 13.3N last period. The current position is and has been close to the long term mean. In the east from 20-35E, the latest ITCZ average position was near 12.1N, also very close to the long term mean.
May 1-10 2004 - The African portion of the Intertropical Convergence Zone was located near 12.2 degrees north when averaged from 15W-35E and over the ten day period. The overall position moved very little, though the long-term mean is now located near 12.7N. During the period, the ITCZ moved north in the area near Mali, Burkina Faso, and western Niger, though a southward progression was noted over eastern Nigeria, Chad, and western Sudan. These contradictory movements resulted in little overall movement from the previous period. Though rains increased in parts of Nigeria, Cameroon, southwestern Ethiopia, and western Kenya during the period, upper level dynamic conditions led to decreased precipitation throughout much of the remainder of the area. The current ITCZ position from 10W-10E is now slightly south of normal and is located near 13.3N compared to the 1988-2003 mean of 13.9N. The eastern region (20-35E) ITCZ is now very close to the normal position of near 11.3 degrees north. As a note, during the past four periods, it has been seen that the ITCZ has been markedly south of normal in extreme western regions near Senegal and Guinea, while the extreme eastern zone in eastern Sudan has been north of normal during each period.
April 21-30 2004 - The ITCZ over Africa moved, on average, nearly 1.4 degrees northward from its position during the second ten days of the month. Moving northward much more quickly than normal, this placed the ITCZ very close to its overall longitude-averaged 1988-2003 position of 12.1N. The recent movement northward, when averaged over the ten day period, was very consistent throughout the entire area, and the leading northward portion of monsoonal rainfall corresponded fairly well to the analysis. Compared to the previous period, rainfall increased throughout much of the ITCZ region, especially near the Nigeria / Cameroon border where over 200 mm of precipitation was seen. Examining the western ITCZ region from 10W-10E, the current average position is near 13.8N, while the long term mean is around 13.4N. The ITCZ in the region moved around 1.1 degrees north from last period. The current position of the eastern ITCZ region from 20-35E (11.1N) is very close to the long term mean. Thanks to stronger southerly winds in the areas near Cameroon, CAR, and Sudan, the strong southward bias seen during the previous period has greatly diminished during the final ten days of April 2004.
April 11-20 2004> - The African portion of the Intertropical Convergence Zone remained nearly stationary when averaged longitudally from 15W-35E, though regionally varied movement was seen. Overall, the average position of the ITCZ was near 10.7N, compared to the 1988-2003 mean of 11.4N during the period and last period's average of 10.6N. This southward deviation from normal arose from displacement near Sudan, CAR, Chad, and near the Atlantic coastal region. Precipitation corresponds well with the ITCZ position this period, and compared to the previous period, rainfall increased in parts of northern Togo and Benin, but generally decreased elsewhere. Zooming in on the west from 10W-10E, the current average position was near 12.7N, compared to the climatological mean of 12.6N and last period's 11.7N. The northward progression is on track for the year. In the east from 20-35E, the average location of the ITCZ moved to the south from the previous period (9.7N) and was located near 9.3N. The latest average is around half a degree south of normal.
April 1-10 2004 - The longitude-averaged position of the ITCZ was near 10.6 degrees north, compared with the 16 year mean of 10.3 north. Healthy rainfall occurred in eastern areas of the continent, including much of Ethiopia, western Somalia, Kenya, Uganda, and southern Sudan. While near normal rains fell in central areas, rainfall was somewhat erratic and lighter than normal in the western countries of Ghana, Côte d'Ivoire, Liberia, and Sierra Leone. Examining regions individually, the ITCZ from 10W-10E averaged near 11.7 degrees north, very close to the mean position for the period. An observed southward dip near extreme western areas does not figure into the regional calculation. In the east from 20-35E, a northward push of winds during the currentperiod helped to move the ITCZ to the north of its long term mean. The current position is near 9.7N, while the long term mean is closer to 8.7 degrees north.
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