Increasing rain chances mid week into the weekend.
Cold high pressure that has been over the southern plains the last few days is starting to move eastward while another surge of cold Canadian air is moving across the Midwest toward the SE US this morning. This secondary surge of high pressure will bring a glancing blow of cooler and drier air into SE TX today into Tuesday. At the surface, a trough of low pressure has formed over the western Gulf of Mexico and this trough will tighten and slowly move northward toward the TX coast over the next 36-48 hours. Initially dry air over the region will preclude any clouds and rainfall today into Tuesday, but moisture begins to approach form the southwest late Tuesday with a warm front as the coastal trough drifts northward. Additionally upper level disturbances will begin to impact the region from the southwest adding additional lift. The coastal trough will favor northeast surface winds through early Wednesday as the warm front lifts northward over the coastal waters and then inland over the region on Wednesday.
With expanding lift and deepening moisture Wednesday widespread showers and thunderstorms will likely result. Warm front will act as a surface focus for enhanced lift while slowly moving northward over the region. Moisture profiles on Wednesday show a significant increase in moisture availability along with saturation throughout the air mass so heavy rainfall looks to be on the table. Nothing is screaming flash flooding with this setup, but slow moving warm fronts always have to be watched for excessive rainfall given the parameters in play. Showers and thunderstorms likely to carry over into at least early Thursday before being pushed toward the coast or offshore Thursday afternoon into Friday as a front approaches from the north. Main question is does this front push offshore and limit rain chances late Thursday into Friday or stall inland keep rain chances going. Regardless, any drying trend will be brief as an upper level storm system will approach Texas from the west this weekend. Old stalled front somewhere over or offshore of the area will return northward with a warm and humid air mass in place. Upper level system looks to eject across the southern plains late in the weekend (maybe Sunday) with a line of showers and thunderstorms. Pattern looks to quickly reload with another system approaching early next week.
Rainfall amounts Wednesday and Thursday of 1-2 inches is likely with isolated higher amounts. These higher totals would be under any areas of cell training from southwest to northwest along the warm front that will be pushing slowly inland. While much of this rainfall will be welcomed to keep drought conditions at bay, there could be periods of heavy rainfall that cause some street flooding in isolated areas.
