Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
225 FXUS64 KHGX 172327 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 627 PM CDT Thu Jul 17 2025 ...New AVIATION... .KEY MESSAGES... Issued at 1258 PM CDT Thu Jul 17 2025 - NHC continues to monitor a disturbance moving over Southeast LA, giving it a 10% chance of development into a tropical system within the next 2 days. - Increasing tropical moisture associated to the disturbance will lead to increased coverage of showers and thunderstorms late tonight through Friday with locally heavy rainfall possible. - Hot and dry weather is expected Sunday through at least mid-week next week. && .DISCUSSION... Issued at 1258 PM CDT Thu Jul 17 2025 Based on the Total Precipitation Water imagery, we are starting to see the western periphery of a warm moist airmass associated to the disturbance (currently located over southeastern LA) move closer to Southeast TX. This airmass is expected to continue to move into our local area during the nighttime and early morning hours with the bulk of its moisture expanding over much of Southeast TX sometime during the mid morning hours. We will first see showers and isolated thunderstorms move into our coastal waters and Galveston Bay region this evening and will expand east northeastward during the overnight to mid morning hours. By early afternoon, the local PWs are expected to rise to 2.1" and 2.4" for much of the area and this is when we should be seeing an increase in shower and thunderstorm coverage. Given how much moisture will be in place from surface to mid level, we may see some pockets of moderate to heavy rainfall, which could lead to ponding of water along roadways and areas of poor drainage. This could affect your commute, thus, make sure to check the latest weather update, the radar feed, as well as the local traffic conditions before departing to your destination. Due to the increase in cloud coverage and rain, our high temperatures on Friday look to be in the upper 80s to lower 90s. PWs will decrease Friday night into Saturday morning as drier air pushes in from the Gulf waters and the bulk of the moisture moves to the north northeast of the Piney Woods region. Some short bursts of slightly higher moisture may be seen during the day on Saturday, and could allow for isolated to scattered showers and isolated thunderstorms to develop during the day. Drier air will move back in on Sunday, leading to lower rain chances, and this dry trend is expected to continue into the mid-week period. Conditions will also gradually warm up Sunday into Wednesday, with high temperatures possibly in the mid to upper 90s for many locations by Tuesday. For more information regarding the tropical disturbance, please refer to the Tropical Discussion below. Cotto && .AVIATION... (00Z TAF Issuance) Issued at 621 PM CDT Thu Jul 17 2025 VFR conditions and light southerly winds will dominate throughout most of the TAF period, though patchy fog could briefly bring MVFR conditions during the early morning hours of Friday. Showers and isolated thunderstorms will be possible on Friday, mainly during the late morning through the afternoon. Shower/storm coverage should be greatest in areas generally east/southeast of Houston with activity tapering off into Friday evening. 03 && .MARINE... Issued at 1258 PM CDT Thu Jul 17 2025 Light to occasionally moderate onshore winds and seas of 2 to 3 feet will persist through the next several days. Seas may increase to around 4 feet late Friday night into Saturday. Rain chances will be on the rise this evening into Friday as a warm moist airmass associated to a tropical disturbance over SE LA, moves into SE TX. There is higher confidence in that the disturbance may not be able to develop into a Tropical Depression, given that it is already moving inland. Thus, NHC has lowered the chance of formation to 10% on the 2PM EDT Tropical Weather Outlook. Although the potential is much lower than yesterday, please continue to monitor the upcoming forecasts, in case of any changes on this systems track and intensity forecast. Drier and warmer conditions are expected to begin Sunday and continue into the mid-week period. Cotto && .TROPICAL... Issued at 1258 PM CDT Thu Jul 17 2025 The disturbance is currently moving inland over Southeast LA while the bulk of the shower and thunderstorm activity remains displaced to the west-southwest of its center. There is more certainty that the disturbance will not be able to develop into a tropical depression, thus, NHC has decreased the chance of formation to 10% on the 2PM EDT Tropical Weather Outlook. Although chances are low, it is still non-zero. Please continue to monitor the latest forecasts in case of any changes to the track and intensity of this system. Regardless of formation, the system could bring periods of moderate to heavy rainfall over portions of Southeast TX from late tonight into late Friday. Cotto && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 73 91 75 92 / 0 20 10 10 Houston (IAH) 78 88 77 92 / 20 60 20 30 Galveston (GLS) 80 88 82 90 / 50 60 20 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ DISCUSSION...Cotto AVIATION...03 MARINE...Cotto