FFMP

This lesson presents information on the Flash Flood Monitoring and Prediction (FFMP) application. This includes a synopsis of the High-resolution Precipitation Estimator (HPE) and the High-resolution Precipitation Nowcaster (HPN). While this lesson presents the basics, more detailed tasks and examples are included in WES Exercise #7(Flash Flood Monitoring and Prediction) on your local WES-2 Bridge machine. RAC will also provide substantial training on FFMP and its inputs, and this lesson is intended to cover the basic procedural knowledge to interrogate precipitation estimates with FFMP.

Required WES Exercise #7 (Flash Flood Monitoring and Prediction (FFMP))

About FFMP

The Flash Flood Monitoring and Prediction (FFMP) system allows you to interrogate radar precipitation estimates and compare to flash flood guidance (FFG) and average recurrence interval (ARI) data on a user-specified duration in support of flash flood warning operations. River Forecast Center FFG is the amount of precipitation required for a given duration to cause flash flooding (e.g. 2.5" in 1 hr). ARIs are the recurrence intervals in years for a given precipitation amount over a given duration based off climatology (e.g. a 4.2" accumulation in 3hrs occurs every 10 years). FFMP conducts its precipitation analysis on a basin-scale, meaning that all of the calculations are done over the area of a drainage basin or larger areas of basin aggregations called Hydrologic Unit Cycle (HUC) layers. 

Starting FFMP Table

All of the FFMP product suite products are available underneath the SCAN menu in the D-2D perspective of CAVE. The FFMP products are grouped together in the “FFMP” section and they are grouped together by quantitative precipitation estimate (QPE) input source. FFMP is configured to use any of your WFOs dedicated radars’ DHR and DPR data as a QPE source, and it is configured for displaying the High-resolution Precipitation Estimator (HPE) and Bias High-resolution Precipitation Estimator (BHPE). The Multi-Radar Multi-Sensor (MRMS) is another QPE source that uses the Surface Precipitation Rate (SPR) products.

FFMP can display Quantitative Precipitation Forecast (QPF) data under the QPF menu which are all 1hr forecasts by default. While QPF data is difficult to use because of its accuracy (note: MRMS QPF doesn't exist and the menu should not be there), the best QPF source is the HPE Nowcast which uses a sophisticated precip tracking and extrapolation scheme. Under the Guidance menu, the RFC FFG for a given day can be loaded as well as the static ARI precipitation values for different intervals (e.g. ARIFFG100->FFMP ktlx ARIFFG100 3.0 HR Display will load the precipitation map for a 100-year precipitation recurrence interval for a 3hr duration). 

After selecting a FFMP Table/Basins Display product to load, FFMP displays a GUI, called the FFMP Basin Table, and an interactive image in the main display panel of the D-2D perspective.

The FFMP Basin Table

The FFMP Basin Table contains comprehensive data on all the drainage basins in your CWA at multiple spatial scales (uses FFMP Basins->FFMP Small Stream Basins and FFMP Small Stream Basins Links maps visible under the Maps menu).

The GUI is divided into five different sections, each discussed below.

Menu bar

The Menu bar (referred to by label "i" in the FFMP GUI image) contains numerous menu buttons that allow users to access many functions and features in FFMP. Many of the menus are not routinely used, but some are used more than others:

• File - Used primarily to save or retrieve FFMP configuration settings.
• Config - Allows users to change the FFMP configuration settings for Link to Frame (i.e., time matching between FFMP Basin Table and main display), Worst Case (aggregate FFMP data will show worst case data vs. average), and Auto-Refresh.
• D2D (commonly used)- Changes what attribute is used to fill county and basin level plots in the main display (typically change between QPE, ratio, and diff to analyze flash flood threat for different durations).
• Layer (commonly used once)- Allows users to change how FFMP Basin Table and FFMP editor display aggregate (i.e., average) data (typically use All & Only Small Basins for primary analysis and County aggregation when identifying individual basin names).
• Zoom - Changes settings for how FFMP Basin Table and FFMP editor display behave when a user selects a county in the Basin Table.
• CWA - Allows users to trim the Basin Table and FFMP editor display down to only counties and basins in a particular CWA.
• Click (commonly used)- Configures the function of the right click in the FFMP editor display (display upstream and/or downstream basin trace or display basin trend graph).

Utility bar

The Utility bar (referred to by label "ii" in the FFMP GUI image) contains three buttons (“Refresh D2D,” “Config Summary,” and “Clear Trace”) and the date/time for the currently displayed data. These buttons are infrequently used. “Refresh D2D” will update the Color Image in the main display panel of the D-2D perspective if you turn off the Auto Refresh. Selecting the “Config Summary” button will display a pop-up window with the current settings for several of the FFMP configuration properties. “Clear Trace” clears the basin trace in the display if you generate one.

Time Duration

The Time Duration section of the FFMP Basin Table GUI (referred to by label "iii" in the FFMP GUI image) allows users to configure the duration of the precip accumulations and flash flood guidance (FFG) displayed in the table and in D2D (e.g. 1hr accumulations, 2.5hr accumulations). The “Gap” value indicates the cumulative amount of time (in hours) that data are not available for the specified duration window. The “Rate” button toggles on/off the display of instantaneous precipitation rate information (i.e., changes Time Duration to 0 hrs) in the FFMP editor display (Note: The Table Body in the FFMP Basin Table will be void of any data when the “Rate” feature is activated).

Attribute Column Titles and Buttons

The attribute column titles (referred to by label "iv" in the FFMP GUI image) are the labels designating which attributes are displayed in the table body. Selecting the title of an attribute sorts the data in the table body by that column. You can select which attributes (e.g. ARIs) you want to display in the table body by selecting the “Attributes...” button.  From the "Thresholds" button you can select the coloring of the cells in the table for each attribute and what gets filtered from the display (requires clear and reload FFMP table to fully apply):

If the data for the attribute falls below the predefined “Filter” value (see above image), that county or basin will not be displayed in the Table Body (except when sorted by Name, then all counties/basins will display in the table). The defaults for attribute coloring and filtering are typically pretty good, so this is not routinely changed.

The Table Body

The FFMP Table can be configured to display the precipitation (QPE, RATE, and QPF) and guidance data (FFG or ARI) in the Table Body. If there is no rainfall over all the geographic entities for the specified precipitation data source and time duration, the table indicates “NA”. The main display is linked to the table. After pressing the Left-Mouse Button on an identifier in the “Name” column of the Table Body, the main display panel zooms and re-centers on that particular county or basin and places an “X” at the centroid of that geographic region. The D-2D display can be sampled, and it will match the contents of the table when they are linked (controlled by Config->Link to Frame option).

FFMP Basin Trend Graphs

One of the more complex and useful analysis tools of FFMP is the basin trend graph. The basin trend graph allows you to view a time trend of rainfall rates, accumulations, and other attributes. The GUI is divided into three different sections, which will be discussed below.

Trend Graph

The trend graph (referred to by label "i" in the FFMP Basin Trend image) plots the time (hours; x-axis) vs. the rainfall rate (inches per hour; y-axis left side) and accumulation (inches; unlabeled y-axis right side which is the same as left-side axis). The default basin trend graph plots the instantaneous rainfall rate (blue line) and the running QPE accumulation (black line with color fill) with respect to time. The default time axis starts with Time = 0.0 hours on the left and scrolls over to Time = -24.0 hours on the right (with “All hr.” selected). The x-axis can also be reversed using the “Reverse X-axis” button in the lower-right portion of the GUI. The time axis has a few different meanings depending on which attribute you are analyzing:

• For Rainfall Rate: Each instantaneous precipitation rate (inches/hr) is plotted with a blue dot in hours before the current time identified on the bottom of the basin trend. As time becomes more negative, the data is farther in the past. For example, if the rainfall rate is 4.09" at Time = -2.0, then that means it rained two hours ago (note that 4.09" inches/hr is the max instantaneous precip rate using the default hail cap at the RPG).
• For QPE: When analyzing the QPE product, time represents the accumulation period for each product. Each black dot represents the accumulation relative to now. For example, if the QPE is 2.5 inches at Time = -3.0, then that means the three hour precipitation accumulation is 2.5 inches.
• For QPF: When analyzing the 1hr QPF products, time represents the accumulation period for each product valid 1hr from now. For example, if the forecast is for 1” of rain in the next hour, and 3.5 inches is plotted at Time = -3.0, then this means the three-hour precipitation accumulation one hour from now is 3.5 inches. QPF is not routinely used on this graph because meaningful QPF is challenging.
• For GUID: When analyzing RFC FFG products, time represents the duration required to trigger flash flooding. If the FFG is 2 inches at Time = -3.0, then than means the 3hr FFG is 2 inches, and if the 3hr QPE is > 2 inches, then flash flooding is possible.

The y-axis scale is fixed, while the radio buttons right above the trend graph allows you to toggle the scale of the x-axis between 1, 3, 6, 12, and 24 hours (note that “All hr.” = 24 hours). The fixed hour graphs (e.g. 6hr) start accumulating on the left axis and can only be compared to FFG at the current time

Plots

This section of the basin trend graph (referred to by label "ii" in the FFMP Basin Trend image) allows you to toggle on/off the different products (particularly toggling on the RFCFFG and ARIs guidance under "GUID") and underlay color shading within the trend graph. The radio buttons in the underlay (“ul”) column allows you to choose which product (“rate,” “qpe,” “ratio,” and “diff”) you want to have color shading (colors come from FFMP table; not frequently used).