WFP FbF Ethiopia 2022 Trigger Monitoring
Last Updated: 21 September, 2022
0. Introduction
This document presents monitoring of the WFP Forecast-Based Anticipatory Action Plan for the 2022 October-November-December (OND) rainfall season in Somali region.
Section 1 of the document describes the rule for triggering action based on forecasts, which was decided in discussion with the FbF Technical Working Group (TWG).
Section 2 of the document presents tables which summarise the forecast information and current weather conditions during each forecast issue month (July, August, September), and whether the forecast would have triggered in that month.
Section 3 relates the triggered forecasts to the Anticipatory Action Plan, and describes which actions have triggered by the most recent season based on the forecast information to date.
This document pulls its data from the IRI Forecast Maptool for Somali Region:
http://iridl.ldeo.columbia.edu/fbfmaproom2/ethiopia-ond
This Maptool was also used by the TWG to determine the specific criteria for anticipatory action described below.
1. Forecast Trigger Rule
The Forecast-Based Anticipatory Action Plan is triggered according to the following rule.
The TWG designates a historical Frequency with which anticipatory action is intended to trigger. For this project, actions associated with a “Moderate” severity drought are meant to trigger in 30% of years, and actions associated with a “Severe” drought are meant to trigger in only 20% of years.
For each year, 1991-present, the IRI map tool retrieves the forecasted probability of non-exceedence associated with the chosen Frequency. For example, the forecast probability at 20% frequency indicates the likelihood during a given year that cumulative OND precipitation will be at least as dry as the 20th percentile in the historical record, or roughly a 1/5 year drought.
The IRI map tool calculates the Threshold for triggering action. This is also based on the Frequency; for example, at the 20% frequency, the threshold is set such that the most probable 1/5th of forecasts in the historical record would have triggered action.
To account for the fact that consecutive seasons of drought can have compounding affects in arid areas like Somali Region, two adjustments are made to the forecast threshold.
If the previous MAM’s season’s rainfall (as measured by the Standardized Precipitation Index, SPI) was below its long-term average, 3.5 percentage points are subtracted from the forecast threshold.
If the most recent monthly measurement of MODIS NDVI (for example, June for the July issue forecast) is below its long-term average, 1.5 percentage points are subtracted from the forecast threshold.
The forecast probability for a given year is compared against the adjusted Threshold. If it is equal to or higher than the Threshold, anticipatory action is triggered for that month. If it is less than the Threshold, no action is taken that month.
This process is followed for each forecast issue month - July, August and September.
This trigger rule is based on the average forecast over Somali region. However, the tables in this document also present information on the forecast measured at the Woreda level, to assist in the targeting of anticipatory action programs within the region.
2. Triggered Forecasts
The following tables list the forecast and pre-season observational data for the 2022 OND season, and whether anticipatory action would have triggered according to the trigger rule described in Section 1.
The tables are organized by forecast issue month. We present results spatially averaged at the region level (which is the basis for triggering action) as well as the woreda level (to assist in beneficiary targeting). In addition, we present the specific anticipatory actions that triggered in that month according to the AAP provided by the TWG.
2.1 July Issue
2.1.1 Region Level
2.1.2 Woreda Level
2.2 August Issue
2.2.1 Region Level
2.2.2 Woreda Level
2.3 September Issue
The September issue forecast for the OND season has not been posted yet. Please check back after the 18th of September.
2.3.1 Region Level
2.3.2 Woreda Level
3. Anticipatory Actions
The specific anticipatory actions to be taken depend on the amount of lead time before the season, and which forecasts have triggered at that time. The following table summarizes the protocol, with the current status highlighted:
3.1 Anticipatory Action Protocol Status
This table summarizes the details of the specific actions to be taken: