The forecast has been rather uncertain so far with this rain event impacting parts of Texas and Louisiana. The ultimate driver of this rainstorm is an upper-level low situated over the eastern Rio Grande River Valley. Upper-level lows are often unpredictable and difficult to forecast, and this most recent event proves out point. The model guidance had a difficult time pinning down where the heaviest of rain will fall on Monday, suggesting that a long-lasting band of rain would impact Houston, but instead it struck the Beaumont-Port Arthur area. It ended up being the fourth wettest June day in Beaumont, Texas on record with a total of 5.89 inches of rain. This was the wettest day since 1959. Houston still received significant rainfall. Monday was the wettest day in the city since Hurricane Harvey, with 2.1 inches.
Then on Tuesday, the forecast remained a struggle in some areas. While Corpus Christi and other towns received a heavy rain through much of the day, promoting Flash Flood Warnings for the same areas multiple times, eastern Houston ended up being dry all day long. Father east, the Beaumont area received additional rain. They have now received 11.2 inches of rainfall since the event first began on Sunday, making it the wettest 3-day period in June.
On Wednesday, disorganized scattered showers and thunderstorms, some of which will be heavy will continue across the same areas of Texas. Lighter rain showers will also stream into the ArkLaTex and Mid-Mississippi River Valley as the moisture gets picked up by the stationary front. Localized flooding will remain a concern, especially at the coast, although the risk for heavy rain will be lower than on Tuesday.
Beginning Wednesday night, the rain will become more isolated as the upper-level disturbance dissipates. This loss in a storm system will prevent a widespread, heavy rain from occurring. Therefore, other than widely scattered showers and storms across eastern Texas and the Gulf Coast states, many areas may actually be dry.
A few more scattered thunderstorm will remain possible across similar areas on Thursday, but by this point in time the main driver of the storms will be the heat and humidity. These storms will then collapse and dissipate overnight. Starting on Friday, the chance for rain will drop down to 10-20% chance as the risk for heavy rain and flooding drops to near-zero.
Rainfall will be heavy, especially through Wednesday. Some locations may receive over half a foot of additional rainfall while a widespread 1 to 2 inches remains forecast.