VIIRS flood observations along the Arkansas River

Heavy rain fell in Kansas, Oklahoma and Arkansas the past few weeks, causing major flooding along portions of the Arkansas River. In the RealEarth image below (i.e. 1930Z on 27 May 2019), major flooding is indicated in orange and red colors and extends from Fort Gibson in northeast Oklahoma to New Blaine in northwest Arkansas.

In the example above, satellite observations are employed to identify the inundated areas, where the Visible Infrared Imaging Radiometer Suite (VIIRS) Flood Areal Extent is utilized. Product is at 375-m spatial resolution and is available for forecasters via Local Data Manager (LDM).

A VIIRS Flood Areal Extent animation is also provided (see below) from 23-28 May 2019, highlighting the flooding along the Arkansas River. The VIIRS Flood Areal Extent discriminates between different scene types (i.e. MS = missing data (black), LD = land (brown), SI = supra-snow ice (mixed ice and water, or water over ice denoted in purple), SN = snow (white), IC = ice (aqua), Cl = clouds (grey), CS = cloud shadows (dark grey), WA = open water (blue)). The product also calculates the floodwater fraction percentage of a pixel (e.g. the product determines if a pixel is 20%, 40%, 100% flooded). The floodwater fraction percentage is from 0-100% and ranges from green-to-red colors. Notice in the animation, the evolution of the flooding along the Arkansas River and the increased flooding near Fort Smith, AR.

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=training/visit/JT_loops/Arkansas_River_Flooding/

For additional perspective on how much rain accumulated over the area, Advanced Hydrologic Prediction Service (AHPS) 7-day and 14-day observed and normal (i.e. average) precipitation images are shown below at 12Z on 30 May 2019. Observed precipitation is expressed as gridded data with a spatial resolution of 4 kilometers, where precipitation is represented in inches. Notice the high precipitation amounts scattered throughout northeastern Oklahoma and northwest Arkansas over the 7-day and 14-day periods, and how observed precipitation values are significantly higher than their respective 7-day and 14-day normal precipitation values. Maximum 7-day and 14-day observed precipitation reached ~5-6 inches and 10+ inches respectively. The 30-day observed and normal precipitation values (not pictured here) also inferred that soils were saturated, suggesting a conducive environment for flooding as well.

7-Day Observed (left) and Normal (right) Precipitation Values

14-Day Observed (left) and Normal (right) Precipitation Values

More flooding along the Arkansas River is expected throughout the next week, where the latest flooding updates can be accessed via the following National Weather Service (NWS) link.

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