From Jeff Linder - doesn't sound promising
***Significant flash flood and river flood threat across TX***
***Potentially dangerous flash flood event for TX next several days***
Hydro situation across this state is dire and additional potentially excessive rainfall is going to push area river systems and lakes to beyond their breaking point. The systems are just overloaded and given what has transpired this afternoon across the Hill Country (4-6 inches of rainfall) flooding is almost ineveitable across this state over the next 5 days.
I am extremely concerned with the potential of this system to drop copious rainfall leading to devastating flooding.
Discussion:
Upper level system will move into TX on Wednesday and park over the state for the next 5 days. Very high tropical moisture levels will surround this upper level feature and there is the increasing potential for this system to begin to take on tropical warm core charateristics which is deeply concerning. Such slow moving systems in the past across this state in the warm season summer months have produced devastating flood events even with dry conditions before onset. Warm core systems generally like to focus extreme rainfall near their circulation cores during the overnight hours and these rains can be extraordinaryTS AllisonTS CharleyTS Frances. Such systems have produced some of the greatest floods this state has ever experienced.
Expect numerous rounds of thunderstorms to onset by Wednesday afternoon. Storm motions really begin to slow down into Wednesday night through Friday with less than 20kts of forward motion. 850mb inflow of 20-30kts is really favorable for providing a rich low level flow of moisturecombine that with strong and near continuous upper level divergence and you have another classic flash flood setup over this state.
Will go with widespread rainfall amounts of 2-4 inches through Fridaybut am almost certain there is going to be significantly higher amounts. Confidence is poor to where these large totals may occurbut right now will favor areas W of I-45 and N of I-10, or the area that has been devastated over the last 6 weeks with flooding. This also highly impacts the Brazos and Colorado basins which are already dealing with devastating flooding. Think storm totals of 10-15 inches are certainly possible in isolated locations especially over our western counties into central TX. Where such rainfall occurs on already very saturated grounds will result in catastrophic flooding. There is just no skill at this range of predicting where these really big totals may occur.
Residents across the entire region should be prepared for significant flash flooding and watershed flooding over the next 5 days. React immediately to rising water and expect flooded roadways. Never drive into high waterlet me say this again NEVER DRIVE INTO HIGH WATER!!!
Brazos River:
Brazos River has risen past the expected forecast today of 53.5 ft and is currently at 54.3 ft this evening and still rising which is smashing the old 1994 record. Flooding across Fort Bend into Brazoria County is devastating. Water is against all the levees in Fort Bend County and back water flooding is starting to cut-off some subdivisions. Large sections of Fort Bend County are flooded with water in parts of Rosenberg and Valley Lodge many feet deep in homes. The river is across the basin divide into Oyster Creek. This situation is Fort Bend and Brazoria Counties moving forward is dire with additional heavy rainfall forecast. Levee protected subdivisions will have to pump additional rainfall as gravity flow into the river is not possible at this time due to the very high levels which could lead to flooding within these subdivisions if rainfall rates exceed to pumping capabilities.