![]() ![]() ![]() The departure from the normal rainfall varies widely across northern Arizona, with many places reporting between a half-inch to 2 inches more rain than usual.īut the rainfall totals in a few places including Bellemont, the Heber Ranger Station, Prescott's Sundog Water Plant as well as Sunset Crater and Walnut Canyon national monuments recorded over 3 inches more rainfall than they typically receive at this point in the season. "So that's just going to add on to these totals and maybe even get farther above normal over the next couple weeks," he said. "The next one to two weeks also seem like they're going to be pretty active and wet in a lot of the area," said Justin Johndrow, a weather service meteorologist. The correlations between the forecast and the observed 7-day series were positive, but low.Almost every location recording rainfall totals across northern Arizona reported measurements far above what they would have normally experienced by this point in the summer monsoon season, according to data from the National Weather Service. Some parameters, such as the mean and the standard deviation of the 7-day total precipitation, were comparable to observations. Weekly precipitation totals were evaluated for the São Francisco Basin. The frontal timing was no longer captured by the model but some indication of the frequency and of the northward movement was given by the model forecast. Transient variability was evaluated by tracking the frontal passages along the eastern coast. Comparison of the Eta Model seasonal forecasts against climatology showed that in general the model produced additional useful information over the climatology. Both driver model and Eta Model forecasts showed some internal variability in the SACZ and over the Andes regions. Five-member ensemble runs were produced for the NDJF rainy season. Comparisons with the CPTEC GCM forecasts showed that the Eta improved considerably the forecasts from the driver model. The evaluation of the precipitation forecast range showed that at the fourth month the forecast skill was still comparable to the first month of integration. The equitable threat score and the bias score showed that the Eta Model forecasts had higher precipitation predictability over the Amazon Region and lower over Northeast Brazil. The monthly precipitation totals indicated that the intra-seasonal variability, such as the monsoonal onset, was reasonably captured by the model. ![]() The major error areas were located along the northern and northeastern coast and over the Andes. In general, the largest precipitation errors were found in ASON season and the smallest in FMAM. The season total precipitation forecasts from the driver model exhibited large overestimate. The total amounts were comparable to observations. The Eta seasonal forecasts represented reasonably well the large scale precipitation systems over South America such as the Intertropical Convergence Zone and the South Atlantic Convergence Zone. The total time integration length was 4.5 months. The sea surface temperature was updated daily with persisted anomaly during the integrations. The lateral boundary conditions were taken from CPTEC GCM forecasts at T62L28. The model domain was configured over most of South America in 40km horizontal resolution and 38 layers. Abstract : Seasonal forecasts run by the Eta Model over South America were evaluated with respect to precipitation predictability at different time scales, seasonal, monthly and weekly for one-year period runs. ![]()
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