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Heavy Rainfall Across the Southwest, Mid-Atlantic and Florida; Fire Weather Concerns in the Northwest and Alaska

Heavy to excessive rainfall may bring flooding to parts of Arizona, New Mexico, Florida, North Carolina, and Virginia today. Recently burned areas will be particularly vulnerable to flash flooding. Gusty winds and low humidity will bring elevated to critical fire weather conditions to parts of the Northwest U.S. and central Alaska today. Read More >

Lower Mississippi RFC

River Forecast Center

Flash Flood Guidance

Weather.gov > Lower Mississippi RFC > Flash Flood Guidance

Gridded Flash Flood Guidance (GFFG) provides a general indication of the amount of rainfall necessary to cause small streams to overflow their natural banks. During heavy rainfall, usage of this guidance must involve combination of rainfall that has already occurred plus any additional rainfall that is expected to fall over the same location, not to exceed the guidance duration (example: 1-hr or 3-hr). It should be noted that these GFFG values are based upon estimates of average soil moisture and stream flow conditions over 4km x 4km grids. GFFG values also assume that the rainfall event will be evenly distributed over the guidance duration. Flooding may occur with less rainfall than indicated in areas of very high rainfall intensities, impervious surfaces (urban areas), or steep slopes.

The 1, 3, and 6 Hourly Gridded Flash Flood Guidance is also viewable on NOAAs GIS Integrated Dissemination Program (IDP) web services. Metadata and additional information on the gridded flash flood guidance and other GIS Web Services can be found at the National Weather Service Data as OGC Web Services site .  Flash flood guidance on a national scale, can be found here.

 

National Precipitation Totals and Flash Flood Guidance