Overview

The Antecedent Precipitation Tool (APT) helps determine whether precipitation conditions at a site were drier than normal, normal, or wetter than normal prior to a field observation date.

Ecobot automates the collection and analysis of NOAA weather station data using the Antecedent Precipitation Tool methodology. This analysis helps environmental professionals document site conditions for wetland delineations, permit applications, jurisdictional determinations, and other regulatory reports.

The generated analysis includes a downloadable PDF report that can be attached to project deliverables and regulatory submissions.

*Note: Learn more about the federal Antecedent Precipitation Tool methodology from EPA and the U.S. Army Corps of Engineers: https://www.epa.gov/wotus/antecedent-precipitation-tool-apt
 

Accessing APT Analysis

From within a Survey, select APT Analysis from the left navigation menu.

Caption: The APT Analysis Configure & Run page displays available sample points, observation dates, coordinates, and analysis settings.

The Configure & Run page displays:

- Available sample points
- Observation dates
- Point coordinates
- Point types (Wetland/Upland)
- Analysis scope settings

Running an Analysis

Step 1: Select Points

Select one or more points using the checkboxes.

Ecobot calculates analyses based on:

- Point location
- Observation date
- Selected analysis scope

Step 2: Choose an Analysis Scope

Use the Analysis Scope dropdown.

Available options include:

Single Point (Default)

Each point is analyzed independently using:

- The point's coordinates
- The point's observation date

This option provides the most detailed point-specific results.

Centroid

Uses:

- The centroid of all selected points
- Each point's observation date

This option can reduce the number of weather station lookups when evaluating larger sites.

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Step 3: Run APT

Select Run APT.

A confirmation dialog summarizes the request before processing.

Review:

- Points selected
- Unique observation dates
- Analysis scope
- Data source
- Estimated processing time

Click Run Analyses to begin processing.

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Monitoring Analysis Progress

After submission, Ecobot automatically switches to the Job Status tab.

The Job Status page displays:

- Pending analyses
- In-progress analyses
- Completed analyses
- Batch progress

Analysis Complete

Completed analyses include:

- Antecedent Score
- Condition
- PDSI Classification
- Season
- Analysis Scope

Reviewing Results

Select the Results tab to review completed analyses.

The Results page provides:

Summary Metrics

- Average score
- Number of Drier than Normal analyses
- Number of Normal analyses
- Number of Wetter than Normal analyses

Point-Level Results

Each completed analysis includes:

- Antecedent Score
- Hydrologic Condition
- PDSI Drought Index
- Seasonal Classification
- Data Source

Downloading the PDF Report

Each completed analysis includes a View PDF Report option.

The generated PDF includes:

- Observation date
- Site coordinates
- Elevation
- Weather station information
- Antecedent precipitation graph
- 30-year precipitation comparison
- Palmer Drought Severity Index (PDSI)
- Seasonal water balance information
- Final antecedent score and condition

Example report outputs include NOAA precipitation comparisons, weather station selection details, and final scoring. The report can be included as supporting documentation in wetland delineation reports and permit submissions.

*Best Practice: Include the APT PDF report as an appendix in wetland delineation reports, jurisdictional determinations, and permit application packages.

Understanding APT Results

APT evaluates precipitation conditions across three rolling 30-day periods prior to the observation date.

Each period receives a classification value:

These values are weighted and combined to calculate a final antecedent score.

Result classifications generally fall into the following categories:

These classifications provide context for hydrology observations and help support wetland determinations.

Troubleshooting

Analysis Remains Pending

If an analysis remains pending longer than expected:

1. Refresh the page.
2. Check the Job Status tab.
3. Retry the analysis.

If the issue persists, contact Ecobot Support.

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NOAA Services Are Unavailable

APT relies on external NOAA weather and climate datasets.

Occasionally NOAA services may:

- Experience outages
- Become temporarily unavailable
- Return incomplete data
- Time out during processing

When this occurs:

- Analyses may take longer than expected
- Requests may remain pending
- Processing may fail
- Results may not be returned

Resolution

1. Wait several minutes.
2. Refresh the Job Status page.
3. Retry the analysis.
4. If NOAA services remain unavailable, try again later.

*Warning: NOAA outages and weather service interruptions are external dependencies and may impact APT processing availability. These interruptions are outside of Ecobot's control.

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No Nearby Weather Station Found

Ecobot automatically selects the most appropriate weather station using:

- Distance from the site
- Elevation similarity
- Data completeness

In rare situations, insufficient weather station data may prevent an analysis from completing successfully. If this occurs, retry the analysis later or contact Ecobot Support.

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Submit Feedback

APT Analysis is currently in Beta.

Use the feedback form to share:

- Feature requests
- Workflow improvements
- Processing concerns
- Data quality feedback

Your feedback helps improve future releases.