Flash Flood Watch has been extended to include Fort Bend and Colorado Counties through Friday evening.
Widespread rains…some heavy…likely over the next 24-36 hours.
Large upper level storm system over northern MX will move eastward into Texas today and exit the state late Friday/early Saturday. Ahead of this system copious Gulf moisture has surged northward resulting in widespread showers and a few thunderstorms over the area. Thus far the heaviest of the storms and rainfall has remained around Matagorda Bay and points southwest with favorable low level convergence is in place. Going forward high resolution guidance is all over the place with placement of the heaviest rainfall and any potential severe weather. There are differences between each of the models on storm organization, mode, and speed which creates a low confidence forecast on where additional heavy rainfall. Much of this is due to the mesoscale nature of the activity with storm clusters and complexes altering the local air mass. For example, a large thunderstorm complex currently moving off the lower Texas coast is generally producing some sinking air and “robbing” low level moisture for additional activity to develop across the Rio Grande plains. The more activity across the lower and mid TX coast and the western Gulf will prevent as much moisture from working into more inland areas thus cutting back on rainfall totals and thunderstorm chances. With that said, there are some guidance members that show significant development of thunderstorms on Friday further northward over SE TX which would bring the threat of heavy rainfall to areas north of I-10. Hence forecast confidence on heavy rainfall, position, and amounts is low.
Additional Rainfall:
Widespread additional amounts of 1-2 inches can be expected over much of the area with lower totals toward the north and higher totals toward the south. Areas within the flash flood watch and south of I-10 could see amounts of 3-5 inches with isolated totals of 8-9 inches through late Friday. Again this is highly dependent on where storm clusters/complexes evolve and any periods of sustained cell training. If deeper convection can become established rainfall rates could approach 2-3 inches per hour…this has been noted this morning north of BRO where over 3.5 inches was recorded in 1-hr…so this air mass is very much capable of some intense short term rainfall rates. Any low level boundaries that form from thunderstorms could become the focus for more sustained heavy rainfall…so trends will need to be watched over the next 24-hrs.
As for any severe threat…the overall threat looks low, but not zero. If a thunderstorm complex is able to evolve over the coastal bend later tonight this could bow out over portions of our coastal areas into Friday morning…some of the 00Z and early 12Z high resolution guidance show this, but not all and I would not say there is a strong signal for such an episode…but should it happen damaging winds will be possible with a bowing line or bowing line segments.
Severe Weather Outlook (Thursday 3-27-25)
