On the heals of several other heavy rainfall events throughout Texas and other areas of the southeast, the region comprising northeast Texas and southwest Arkansas saw a major precipitation event that brought widespread flooding, tornadoes, property damage, and even fatalities from April 29th to the early morning on April 30th. The rainstorms initiated ahead of an area of cyclogenesis in central to northern Texas and tracked towards the northeast as the day progressed. These storms were being fed by warm and very humid air originating off of the Gulf of Mexico, as shown in the NOAA surface analysis plotted below.
With plenty of moisture on-hand and a driving force of instability aloft in the form of a shortwave trough passing through the region, large storms were able to initiate and grow rapidly. This also allowed for consistent storm development throughout the day and into the evening/early morning hours of April 30th.
A MetStorm analysis performed for this event shows periods of very high precipitation during multiple time frames within our analysis window. Two time periods of note are 12 and 14 UTC, in which high radar-estimated hourly rainfall on the order of 3 and 5 inches per hour, respectively. Also plotted below is the radar reflectivity at roughly 12 UTC to illustrate how widespread the thunderstorms became.
A MetStorm analysis is advantageous in deciphering how major this storm event was because of its calculation of the Average Recurrence Interval (ARI), or the expected likelihood of a rainfall event over a bounded region and time frame. Below is the maximum ARI calculated across a 6-hour period during the rainfall event for the Texas-Arkansas-Oklahoma region hardest hit by these storms. The darker the shading, the rarer (more extreme) the amount of rain that fell over that 6-hour window. One area in particular (along the Oklahoma and Arkansas border) experienced an exceptionally rare rainfall event, one that likely occurs once every 500-1000 years, and within that an area with an estimate of over 1000 years. The rainfall in northeast Texas was quite exceptional as well.
Compare these areas of large ARIs to the MetStorm rainfall totals recorded across the area using a combination of rain gauge, radar, and satellite retrieval estimates. Close to 16 inches of rainfall fell in the area along the Oklahoma-Arkansas border for the 48-hour window that our MetStorm analysis took place. And again, in Texas, large areas received close to 10 inches of total rainfall. These heavy precipitation bands led to major flooding for large portions of the analysis region.
Please note that the maps presented here are preliminary and will be updated when new data become available. If you are interested in this product, or any other product from our MetStorm Precipitation Analysis tool, please email us or send us a message though our contacts page here.