Flood Forecast Tool

6-hour and 24-hour QPF Tool       

(Updated: 2018-05-01 - version now in file name)


We have created, and regularly update, a QPF spreadsheet tool that gathers data from National Weather Service (NWS) forecast web pages into excel worksheets and present the 6-hour and 24-hour QPF for three to four days in the future. It also gathers our Rain Gauge Page data for side-by-side analysis with the NWS forecasts. It can be used with the 7-5-3-2 protocols to assess the likelihood of flooding.

The tool is an excel workbook developed in Microsoft Excel 2010. It will also open and function in earlier Excel versions though some of the colors and functionality may be different. Tabs with text explaining the The Purpose and Use as well as Instructions are included on separate worksheets in the workbook.

On occasion, the NWS will change the web pages that this tool reference and the tool will have errors. We use the tool frequently and fix it so it works correctly and upload it again as soon as possible. We have no control over the NWS website and so can only react and correct our tool when we notice the problems.


QPF Tool Spreadsheet


QPF Tool for General County Locations (1.74 MB .zip file)
This tool uses five general locations throughout the county. It is adequate for looking at the QPF for those locations. It contains a "dash board" that displays the five locations QPF forecast data as well as data measured by the FC District's rain gauges data.

Contra Costa Rain Gauges Spreadsheet


CCGauges spreadsheet (0.54 MB)
This spreadsheet reference the Flood Control District Rain gauge RainTable. It does not include the locations used in the above mentioned QPF Tool for General Locations to show the 2-hour forecast. This spreadsheet is simpler and lighter. It does calculate the Year to Date (YTD) percent normal rainfall for the county rain gauge locations.

When to consider taking action.

Contra Costa County is susceptible to flash flooding. If you live in a flood prone area, you should have a personal evacuation plan and keep an eye on the weather and the antecedent conditions.

As the storm progresses, the following approximate trigger intensities historically have produced local flooding:

In WEST OR CENTRAL COUNTY


1.00" in a 2-hour period, 0.70" or more in a 1-hour period 

In EAST COUNTY


0.60 to 0.70 in a 2-hour period, or 0.40" or more in a 1-hour period.

See instructions on accessing the National Weather Service web sites below. You should review your personal evacuation plan and take precautions to protect personal property if you sense flooding may occur. 

Other Factors


In addition to antecedent rainfall conditions, several other factors can also contribute to flooding. These factors include
  • debris blockage of drainage infrastructure and
  • sudden localized downpours that are not detected by rain gauges.
This antecedent conditions information should be used in conjunction with small stream advisory warnings broadcast/posted by the National Weather Service as well as common sense.

Disclaimer
The Contra Costa County Flood Control & Water Conservation District (FC District) is not responsible for predicting flooding, warning property owners of eminent flooding, or ordering evacuations. The above information is presented to provide an indication of potential for flooding based on experience and review of limited historic rainfall data. The FC District does not warranty, guarantee, or certify the accuracy of the rainfall data. The data accuracy and availability can be compromised due to equipment failure, power loss, equipment defects, loss of calibration, or Internet/radio communication equipment failure of equipment provided by others.