The National Water Model (NWM) forecasts streamflow over the entire continental United States. It is a hydrologic model that predicts the flow in over 2.7 million stream reaches of the National Hydrography Dataset Plus, mathematically modeling physical processes such as snowmelt, infiltration, and the movement of water through soil layers in order to determine how much of the NWS precipitation forecast becomes runoff, then routing that runoff through the river network.
View monthly maps showing the probability for precipitation ranking in the top, middle, or bottom third of historical observations. Outlooks that favor drier or wetter periods can raise awareness of the potential for changing conditions.
The National Hurricane Center monitors marine weather and indicates the chance that disturbances will develop into tropical storms. For storms that do develop, the site shows predicted paths and storm status. Monitor this site to be aware of the potential for tropical storms and/or hurricanes.
Check the probability that cumulative rainfall will exceed user-defined thresholds within the next three days during 6- to 24-hour intervals. This forecast can serve as an early alert for potential flooding.
This interactive map shows regions where the risk of having a seasonal extreme in temperature or precipitation is elevated during El Niño or La Niña conditions. Decision makers can identify areas that have an increased or decreased risk of extreme warm/cold (or dry/wet) seasons, and plan accordingly.