textproduct: Houston/Galveston

KEY MESSAGES

Issued at 1237 PM CDT Sat Jul 5 2025

- Scattered showers with a few thunderstorms will continue to today, mostly west of I-45.

- The next best chance for rain and storms returns Monday and Tuesday with the arrival of a disturbance from the east.

- Temperatures are forecast to trend upward towards the second half of the week. But some uncertainty exists with the forecast beyond Wednesday.

DISCUSSION

Issued at 1136 AM CDT Sat Jul 5 2025

The quasi-stationary mid-level disturbance that has brought very heavy rainfall to portions of Central Texas continues to have an effect on our local atmosphere today. Scattered showers and isolated thunderstorms have already developed across our western counties, producing locally heavy downpours in the Brazos Valley. Shower and thunderstorm coverage is expected to expand eastward as daytime heating provides added instability. Not everyone will receive rain. But some communities are likely to experience heavy downpours along with some thunder and lighting. Best chance of showers and thunderstorms will be west of I-45. But isolated activity to the east of I-45 is possible as well. These showers and storms are expected to decrease in coverage as we lose daytime heating this evening. The aforementioned system is drifting slowly southward and is expected to be far enough away from the area to not enhance atmospheric lift by Sunday. In addition, lower PWATs are expected to filter into the area from the east. Therefore, the chance / coverage of showers and thunderstorms is expected to be lower. That being said, day time heating coupled with the sea breeze and sufficient moisture could still spark off isolated showers and thunderstorms.

Our attention will turn east as we finally get rid of the current system over Central Texas. Middle and upper level water vapor imagery coupled with the current 500MB RAP analysis show a clear mid/upper trough over the eastern Gulf. This trough will drift westward over the next couple of days, influencing the SE Texas atmosphere by Monday and Tuesday. The added lift on top of the typically high July PWATs would tend to enhance the convective initiation potential from the sea breeze / bay breeze as well as other mesoscale processes that interact with the heating of the day. Model guidance isn't very consistent regarding rainfall coverage. But a mid/upper low moving into Texas from the Gulf is usually, at a minimum, an enhancer of the summertime diurnal convective cycle. The best chance of showers and thunderstorms on Monday and Tuesday is across our southern and eastern counties.

Beyond Tuesday, computer models continue to insist on a hotter and less rainy pattern. Increasingly robust and suppressive ridging is pretty normal as we head deeper into July. Our forecast for Wednesday-Friday features hotter temperatures and lower PoPs. But we are keeping a daily risk of showers and thunderstorms through the end of the week. This is in part due to the fact that long term guidance has had a recent dry bias. In addition, there are already some signals in the guidance showing how the forecast could become wetter later in the wake. Despite the general increase in ridging, global models are hinting at a potential weakness in the ridge sneaking its way southwest from the Midwest to the Arklatex region on Thursday and Friday. Current Thursday/Friday PoPs are low. But those PoPs will have to increase if the trough can extend a little farther south and west. And even if it doesn't, enhanced convection to our north and east can sometimes have a mesoscale ripple effect that can turn a dry forecast into a wet one.

Temperature wise, we expect highs to average in the low/mid 90s through Wednesday, then mid/upper 90s by Thursday and Friday. But those hotter temperatures will be dependent on whether or not ridging continues to build or not. The humidity will remain quite fierce. So peak daily heat index values are likely to remain in the triple digits. Drink your water y'all!

AVIATION

(18Z TAF Issuance) Issued at 1136 AM CDT Sat Jul 5 2025

Scattered shra and isolated tsra likely to continues west of I-45 this afternoon. Confidence is lower regarding shra coverage for areas near and to the east of I-45. Therefore, we cannot rule out shra/tsra as far east as IAH. But the best chance of shra/tsra will be over the Brazos Valley region (CLL). Any shra/tsra should diminish this evening. Localized areas of MVFR conditions possible late overnight into the morning hours.

MARINE

Issued at 1136 AM CDT Sat Jul 5 2025

Light to moderate onshore flow along with generally low seas expected through the forecast period. We will also keep a daily risk of isolated to scattered showers and thunderstorms in the forecast through the end of the week. Beyond today, the best chance of showers and storms will be on Monday and Tuesday as a mid/upper disturbance approaches from the east.

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 73 92 72 93 / 10 10 0 10 Houston (IAH) 75 94 75 93 / 10 20 10 40 Galveston (GLS) 81 90 81 90 / 10 10 10 30

HGX WATCHES/WARNINGS/ADVISORIES

TX...None. GM...None.