National Water Model (Hourly Anomaly Forecast)

<p><span style='color:#b22222;'><strong>Retirement Notice:</strong></span><strong>&nbsp;This item is in </strong><a target='_blank' href='https://goto.arcgis.com/lifecycle/content' rel='nofollow ugc noopener noreferrer'><strong>mature support</strong></a><strong> as of November 2024 and will be retired in December 2026. A&nbsp;</strong><a target='_blank' href='https://www.arcgis.com/home/item.html?id=cadb9f7713ad443f85aa34a01ddb7785' rel='nofollow ugc noopener noreferrer'><strong>new version of this item</strong></a><strong>&nbsp;is available for your use. </strong>Esri recommends updating your maps and apps to use the new version.</p><div><p><span>The&nbsp;</span><a target='_blank' href='https://water.noaa.gov/about/nwm' rel='nofollow ugc noopener noreferrer'>National Water Model</a><span>&nbsp;(NWM) is a new product from the National Weather Service that forecasts streamflow volume and velocity&nbsp;over the entire continental United States. It is a hydrologic model that predicts the flow in every river reach of the&nbsp;</span><a target='_blank' href='https://www.arcgis.com/home/item.html?id=5600cf6b463043ec97b764fb258997be' rel='nofollow ugc noopener noreferrer'>National Hydrography Dataset</a><span>,&nbsp;mathematically&nbsp;modeling physical processes like&nbsp;snowmelt, infiltration and the movement of water through soil layers in order to determine how much of the&nbsp;</span><a target='_blank' href='https://www.arcgis.com/home/item.html?id=b3ae384875284b8891196a2f132deb81' rel='nofollow ugc noopener noreferrer'>NWS precipitation forecast</a><span>&nbsp;becomes runoff, then routing that runoff through the river network.&nbsp;This is the short term forecast, which is run every hour, predicting streamflow over the next eighteen hours at one hour intervals.&nbsp;Rivers are symbolized according to how the streamflow differs from the monthly normal.</span></p><div><div><div><strong>What Can You Do With This Layer?</strong></div><div>This map service is designed for fast data visualization. Identify features by clicking on the map to reveal the pre-configured pop-ups. View forecast&nbsp; data sequentially using the time slider, which is set to one hour intervals by default, by Enabling Time Animation. This layer type is not recommended for use in analysis.</div><div>&nbsp;</div><div><div><span style='font-size:x-large;'>Revisions</span></div><ul><li><strong>Sep 23, 2020</strong>: Updated '<strong>qout</strong>' field values for Water Bodies. Null values are now being replaced with '-9999' in order to correct an identify issue at small scales. Also updated Pop-Up to reflect that the '<strong>qout</strong>' value is Not Available (N/A).</li><li><strong>Nov 18, 2021</strong>: Updated Feature set to v2.1 of the NWM data. Added '<strong>qnormal</strong>' field to provide expected monthly flow for given forecast.</li></ul></div></div></div></div>