textproduct: Houston/Galveston

KEY MESSAGES

- Multiple rounds of showers and thunderstorms are expected through Mother's Day weekend, including after midnight tonight into early Saturday morning and likely after sunset on Sunday.

- Additional rainfall totals of at least 0.5 to 1.5 inches (with locally higher amounts) are likely through the end of the day on Sunday.

- Mostly drier and warmer weather is expected through next week.

DISCUSSION

Issued at 1221 AM CDT Sat May 9 2026

The atmosphere over southeast Texas remains persistently moist thanks to mid-level troughing that continues eastward, funneling/injecting more vorticity into southwesterly flow as anticipated on satellite imagery across West Texas. This is evident from nearby 00Z soundings with PWAT values ranging well above the 75th percentile at 1.75-2 inches. While the lift to instigate more convection remains more scarce across southeast Texas (especially compared to north Texas), a new round of convection developing over the Red River Valley is expected to proceed southward and introduce a chance of precipitation across Piney Woods zones in the early morning hours on Saturday. Forecast uncertainty has been elevated in this synoptic pattern thanks to the mesoscale nature of disturbances and weaker forcing. Drier antecedent soils and somewhat drier precipitation trends will boost 1 and 3-hour flash flood guidance thresholds, leaving the best chances of any flash flooding further east of the I-45 corridor through the day on Saturday. Additional parameters still favor the chance of severe thunderstorm development (mainly elevated mid-level lapse rates near 7 J/kg) for a threat of large hail with any convection that can become robust enough.

Sunday's frontal boundary will provide the long-missing lift necessary for another round of convection (some of which could be severe) carrying the potential for damaging winds and large hail. This round of stronger storms is expected to enter southeast Texas later on Mother's Day (well after sunset) and clear the area by Monday morning, leaving a lower chance of rain for any daytime plans. By the beginning of next workweek, a reprieve arrives in the form of cooler temperature maximums/minimums (upper 80s/mid 60s, respectively). Medium-range guidance suggests ridging gradually displacing northwesterly flow aloft through the week as it exits the Intermountain West, keeping mostly dry conditions in place areawide. Temperatures will respond in kind by the end of the week, nearing the 90-degree mark in some areas.

Cassel

AVIATION

(12Z TAF Issuance) Issued at 612 AM CDT Sat May 9 2026

Mix of LIFR to MVFR conditions for much of SE Texas this morning due to lower cigs and areas of patchy to dense fog reducing vis. Fog will burn off and cigs will gradually lift after 15Z, scattering out in the afternoon. IAH and sites northward could see some iso showers for the rest of the morning, although impacts should be minimal. A larger area of showers is currently moving into the Matagorda Bay region and could affect sites in and south of HOU through the mid morning hours. Another round of showers and storms are possible during the late afternoon to early evening hours.

Winds will remain light and variable for much of the day, becoming SE at 5-10 KTS later in the afternoon. Model guidance is suggesting MVFR cigs returning during the overnight to early Sun morning hours, along with areas of patchy fog.

Cotto

MARINE

Issued at 1221 AM CDT Sat May 9 2026

With a warm front remaining just offshore, a 30-50% chance of thunderstorm development will continue through the next 48 hours carrying the threat of locally strong downdrafts. By Sunday night into early Monday morning, another round of thunderstorms will carry an additional chance of strong winds offshore. Post-frontal northerly winds will remain elevated offshore through Monday before returning back onshore by Wednesday. These post-frontal winds are expected to remain below the threshold requiring issuance of a Small Craft Advisory at this time.

Cassel

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 84 69 86 67 / 20 0 0 80 Houston (IAH) 85 72 88 71 / 30 0 10 70 Galveston (GLS) 82 76 83 74 / 30 0 0 50

HGX WATCHES/WARNINGS/ADVISORIES

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