Spectral Budget Analysis of the Short-Range Forecast Error of the NMC Medium-Range Forecast Model

This paper identifies fundamental issues which prevent the effective uptake of climate information services in Nigeria. We propose solutions which involve the extension of short-range (1 to 5 days) forecasts beyond that of medium-range (7 to 15 days) timescales through the operational use of current forecast data as well as improve collaboration and communication with forecast users. Using newly available data to provide seamless operational forecasts from short-term to sub-seasonal timescales, we examine evidence to determine if effective demand-led sub-seasonal-to-seasonal (S2S) climate forecasts can be co-produced. This evidence involves: itemization of forecast products delivered to stakeholders, with their development methodology; enumeration of inferences of forecast products and their influences on decisions taken by stakeholders; user-focused discussions of improvements on co-produced products; and the methods of evaluating the performance of the forecast products.We find that extending the production pipeline of short-range forecast timescales beyond the medium-range, such that the medium-range forecast timescales can be fed into existing tools for applying short-range forecasts, assisted in mitigating the risks of sub-seasonal climate variability on socio-economic activities in Nigeria. We also find that enhancing of collaboration and communication channels between the producers and the forecast product users helps to: enhance the development of user-tailored impact-based forecasts; increases users' trusts in the forecasts; and, seamlessly improves forecast evaluations. In general, these measures lead to more smooth delivery and increase in uptake of climate information services in Nigeria.

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The role of arctic forecast errors in the evolution of northern extra-tropical forecast skill

10.5194/egusphere-egu2020-3606 ◽

2020 ◽

Author(s):

Thomas Haiden

Keyword(s):

Forecast Error ◽

Weather Prediction ◽

Polar Vortex ◽

Forecast Skill ◽

The Arctic ◽

Forecast Errors ◽

Ensemble Forecasts ◽

Medium Range Forecast ◽

Medium Range

<p><br>Increases in extra-tropical numerical weather prediction (NWP) skill over the last decades have been well documented. The role of the Arctic, defined here as the area north of 60N, in driving (or slowing) this improvement has however not been systematically assessed. To investigate this question, spatial patterns of changes in medium-range forecast error of ECMWF&#8217;s Integrated Forecast System (IFS) are analysed both for deterministic and ensemble forecasts. The robustness of these patterns is evaluated by comparing results for different parameters and levels, and by comparing them with the respective changes in ERA5 forecasts, which are based on a &#8216;frozen&#8217; model version. In this way the effect of different atmospheric variability on the estimation of skill improvement can be minimized. It is shown to what extent the strength of the polar vortex as measured by the Arctic and North-Atlantic Oscillation (AO, NAO) influences the magnitude of forecast errors. Results may indicate whether recent and future changes in these indices, possibly driven in part by sea-ice decline, could systematically affect the longer-term evolution of medium-range forecast skill.</p>

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A Sea-Ice Albedo Experiment with the NMC Medium Range Forecast Model

Weather and Forecasting ◽

10.1175/1520-0434(1994)009<0453:asiaew>2.0.co;2 ◽

1994 ◽

Vol 9 (3) ◽

pp. 453-456 ◽

Cited By ~ 4

Author(s):

Robert W. Grumbine

Keyword(s):

Sea Ice ◽

Forecast Model ◽

Medium Range Forecast ◽

Medium Range

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Diagnosis of the Source and Evolution of Medium-Range Forecast Errors for Extratropical Cyclone Joachim

Weather and Forecasting ◽

10.1175/waf-d-16-0026.1 ◽

2016 ◽

Vol 31 (4) ◽

pp. 1197-1214 ◽

Cited By ~ 7

Author(s):

William S. Lamberson ◽

Ryan D. Torn ◽

Lance F. Bosart ◽

Linus Magnusson

Keyword(s):

Western Europe ◽

Forecast Error ◽

Extratropical Cyclone ◽

Ensemble Prediction ◽

Forecast Errors ◽

Ensemble Prediction System ◽

Medium Range Forecast ◽

Medium Range ◽

The Difference ◽

Range Forecasts

Abstract Medium-range forecasts for Cyclone Joachim, an extratropical cyclone that impacted western Europe on 16 December 2011, consistently predicted a high-impact intense cyclone; however, these forecasts failed to verify. The potential source and propagation of forecast errors for this case are diagnosed from the 51-member European Centre for Medium-Range Forecasts Ensemble Prediction System initialized 5 days prior to the cyclone’s landfall. Ensemble members are subdivided into two groups: one that contained the eight members that had the most accurate forecast of Joachim and, the other, the eight members that predicted the most intense cyclone. Composite differences between these two subgroups indicate that the difference between these forecasts originate in tropopause-based subsynoptic waves along a deep trough in the eastern Pacific. These errors move eastward over a northern stream ridge centered on the west coast of North America and modulate the evolution of a trough that dives equatorward out of Canada and is associated with the development of Joachim. Forecast error calculations and relaxation experiments indicate that reducing forecast errors associated with these subsynoptic features leads to more accurate forecasts. These results present further evidence that subsynoptic errors, especially those originating in the warm sector of a cyclone, can be a significant source of downstream forecast errors.

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