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NOAA’s National Weather Service Guide to Hydrologic Information on the Web Prediction Services

Your gateway to web resources provided through NOAA’s Advanced Hydrologic Prediction Service begins here: water.weather.gov

U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Weather Service September 2015

NOAA/PA 200850 National Map

This web page shows the status at all National Weather Service forecast locations.

Clicking on this tab Click this button to have the Click this button to bookmark Top row shows options Bottom row shows shows locations where map automatically update or share your view. available on the NWS options available under observations are color- every 5 minutes. home page. the “Water” category. coded according to their current flood status. Clicking on any location brings up a regional map showing a NWS Clicking on this tab shows Weather Forecast Office (WFO) locations that are color-coded Hydrologic Service Area (HSA) according to the maximum containing that location. forecast flood category through the entire period. Because the Use drop-down menus to show period for which a forecast is locations across different regions, prepared varies from RFC to including states, NWS WFO HSAs, RFC, the entire period generally NWS River Forecast Center (RFC) varies from 2 to 10 days. areas of responsibility, and USGS water resource regions. Drop-down menu allows users to display all locations, only locations, Click here to only display locations hydrograph/probability forecast currently in flood. locations, inundation mapping locations, near or above locations, and at or below NWS river forecasts and Color-coding is used on map Hover over this box to learn more low water threshold locations. flood products are critically locations to indicate flood status. about UTC time. dependent on the USGS Click on a colored box and only gaging network. points in that flood category are displayed. Regional Map This web page shows the flood status of river forecast locations in the selected region. Selecting a specific river/stream location provides access to localized information. Clicking on this tab Color of icon indicates shows locations where category of flooding. observations are color- coded according to their Extensive inundation of current flood status. structures and roads. Significant evacuations of people and property. Clicking on this tab shows locations that Squares Some inundation of are color-coded indicate structures and roads according to the highest locations where near stream – some forecast flood category short-term evacuations of people through the entire forecasts are and property. period. Use the forecast available. Minimal or no property timeline slider at the top damage, but possibly of the map to adjust the some public threat. forecast period. For Circles indicate River or stream level example, clicking on the locations where approaching flood stage. Day 1 tick mark shows short-term and probabilistic locations that are color- River or stream level forecasts are coded according to the below flood stage. highest forecast flood available. category through Day 1. Observations are not current. River or is not operating. Flood category has not been defined. Navigation arrows allow Diamonds indicate Use checkboxes to turn users to move to locations where only overlays off and on and slider River or stream level at neighboring WFO observations are bars to adjust the or below low water HSAs. available. transparency of the overlays. threshold.

Hydrograph

Mouse over a specific river/stream location on a regional map to display the location’s five-character identifier, name, and hydrograph. Click on the river/stream location to go to the main hydrograph page. The hydrograph provides recent observations and for many points a forecast for the next few days. Tabs at the top of the hydrograph allow a user to display other graphical information for the river/steam location.

Latest observed stage Coordinated Universal Time with time and date. (UTC) scale. Flood stage is included if available. Color-coded flood categories for location being viewed, with stage where Peak observed and each category starts. Flood forecast stages during severity color scheme is time period covered by consistent throughout these graph. web pages.

Scale for indicating Scale for indicating water water level in terms of level in terms of flow in stage in feet (ft). thousands of cubic feet per second (kcfs) or cubic feet per second (cfs) if available. Observed trace – indicates water level trends over past Forecast trace – shows several days. expected water level trend over next few days.

Vertical line marks the Local time scale. current viewing time. Weekly Chance of Exceeding Levels This graphic provides the probability of exceeding various river/stream levels during the next three months given the weather patterns in past years and the best available long-term forecasts. Hover over this tab to select the type of Lines for flood category probability information you wish to view. levels use the same color scheme shown on the flood hydrograph and other web pages.

Each colored section of vertical represents a range of probabilities On the web, click on “About (e.g., 10% to 25% for this graph” for description of the yellow bars). Range this plot. of stages corresponding to those probabilities Example: For week of 9/13 can be found on the left to 9/20, the bottom of the scale of the graph (see yellow bar shows there is a example). 25% chance the stage will exceed about 7.7 feet and the top shows there is a 10% chance the stage will exceed Bars are shown in about 8.5 feet. weekly increments. Allows user to display probabilities in terms of Provides explanation of stage, , or weekly the graph. flow volume. Precipitation

This web page shows the digital precipitation estimates used in National Weather Service river forecast models.

Allows download of digital data in Third row shows shapefile or netCDF format. options available under “Precipitation” category.

Feedback from users is Description of precipitation display highly valued. and its features.

Precipitation depth in selected units. Provides list of links to other precipitation-related web pages. User-selectable overlays.

Select units for display.

Selectable timeframe: archived yearly, archived monthly, or archived daily data. Area covered: River Forecast Center (RFC) area of responsibility, state, full CONUS + Puerto Rico, Weather User can select year and month Forecast Office (WFO), or or year, month, and day USGS water resource depending on archive timeframe region (defaults to full chosen. CONUS + Puerto Rico). Interactive Snow Information This web page (www.nohrsc.nws.gov/interactive/) provides an interface to remotely sensed snow information.

Control map by zooming Latitude and longitude in or out. of cursor location. User can enter coordinates When box is red, clicking to recenter map. and dragging while holding down mouse button and then releasing zooms in on Map shows portion of created rectangle area. U.S. currently being displayed. Select type of data to display – e.g., snow water equivalent, snow depth, or snow water equivalent change. Key to information being qqq displayed. Select date and time to display.

Select geographic features to display. Elevation key for base map. Select display units (U.S., metric).

Miscellaneous display Directions for use of control features. interactive features. Flood Inundation Map

This interactive web page shows the spatial extent of possible or expected flooding in a given area. It can be used to show if roadways and structures will be impacted by floodwaters. At the limited number of forecast locations where inundation maps are currently available, this web page is accessed by clicking on the inundation mapping tab on the hydrograph web page. In collaboration with partners, this product will be expanded to new locations.

Set display: inundation Select levels, flood categories, background: or current forecast. imagery, street, topographic, USGS topographic, and light grey canvas maps.

Color scale for depth of Flood category display inundation.

Flood inundation at stage = 18.5 ft is shown on map. Current forecast display Download data and links to supporting documents. Menu for inundation levels shown on map: stage = 18.5 feet is highlighted in yellow. Link to user guide video on YouTube. Clicking anywhere on map displays a red marker. Water depth, risk area latitude, longitude, and and nearest geo-located structures overlays address is provided for are displayed that location. when flood inundation map is viewed for the first Slider for adjusting time. transparency of overlay.

Latest stage observation. Use tear-away to move map overlay controls. Stage at inundation level currently shown on map.

Describes stage where each flood category begins.

List of historical flood crests. Experimental Long-Range River Flood Risk Map

This interactive web page shows the long-range (3-month) risk of minor, moderate and major river flooding at locations where probabilistic forecasts are produced. The risk information is based on NWS Ensemble (ESP) forecasts which are generated for thousands of river and stream forecast locations across the nation.

Clicking on this Click on the map tab shows to display a locations where regional map of there is a the WFO HSA greater than containing that 50% chance of location. exceeding minor, Use the moderate, and dropdown menus major flooding. to view four types of regional maps, Allows user to including state, choose values WFO HSA, NWS of greater than RFC area of 5, 10, 25, 50, responsibility, or 75, 90, or 95% USGS water chance of resource region. exceeding river flood levels On a regional during a 3- map, click on a month period. point to view the Chance of Exceeding Allows user to select the 3-month period of interest. Through the 28th day of the current month, Levels During the 3-month period defaults to the current month, current month + 1 month, current month + 2 Entire Period months. After the 28th day of the current month, the 3-month period defaults to the current month graphic for that + 1 month, current month + 2 months, current month + 3 months. location.

The Advanced Hydrologic Prediction Service, or AHPS, is a program in NOAA’s National Weather Service designed to provide improved river and and water information. AHPS provides a suite of graphical and numeric products over the Internet to assist community leaders and emergency managers in making better life- and cost-saving decisions about evacuations and movement of property before flooding occurs.

To access the water information in this brochure, see: water.weather.gov

Feedback on these web pages is welcome at: weather.gov/contact

NOAA/PA 200850