FXUS64 KBRO 191755 AAC AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1255 PM CDT Tue Aug 19 2025 ...New AVIATION, MARINE... .DISCUSSION... Issued at 1040 PM CDT Mon Aug 18 2025 The mid-level ridge continues to retreat into the Four Corners by late week, as Hurricane Erin swings by the US East Coast. This leaves weaker pressure at 500mb along the western Gulf. Moisture builds through the weekend into early next week as a weak coastal low and trough persist along the lower Texas coast. This helps set up multiple rounds of beneficial rainfall each day through the forecast period, especially Wednesday through Sunday. Overall, there does not appear to be much flow at the surface, leaving the sea breeze to be the main catalyst for initial convection and meandering or colliding outflow boundaries helping to spread the coverage. Slower moving storms with abundant moisture also increases the flooding rain threat. At the moment, WPC has kept a Marginal Risk (level 1 of 4) of excessive rainfall mainly north of the CWA Thursday and Friday, barely reaching into Zapata County. Several CAMs were hinting at strong thunderstorms working southwest across the ranchlands and into the brush country or upper valley late Tuesday afternoon into Tuesday evening. The guidance has diminished the threat some this evening, but would be something to monitor. As the week progresses, abundant cloud cover and better rain chances limit peak heating and stifle instability. Temperatures remain near normal and hot Tuesday, with highs gradually dropping a degree or two each day through the forecast period and lows remaining warm. Expect a Moderate (level 2 of 4) Heat Risk each day. Patchy shallow fog or field fog may develop each night and early morning, especially across the eastern ranchlands and coastal counties. && .AVIATION... (18Z TAFS) Issued at 1236 PM CDT Tue Aug 19 2025 VFR conditions and southerly to easterly flow will prevail outside of a few notable mentions. Showers and thunderstorms continue to be possible along the sea breeze boundary this afternoon/early evening. Isolated convection is possible and may bring brief heavy downpours, gusty winds, and lightning to any sites that find themselves under a shower. Alongside sea breeze showers, an MCS over southern TX is making its way southwestward, bringing a further chance of convection to the region. Confidence is low with this system and not mentioned in TAFs as it is expected to stay further west than sites, but showers/storms at MFE cannot be ruled out. Tomorrow morning, further isolated to scattered showers and storms are possible over the area, moving inland through the day. && .MARINE... Issued at 1236 PM CDT Tue Aug 19 2025 A meek pressure gradient will allow for slight seas and gentle winds out of the south-southeast, becoming moderate in the afternoons and evenings with land-sea breeze. There is a chance of isolated to scattered showers and thunderstorms every day through the weekend, primarily Wednesday through Sunday. Conditions will be degraded in any storms over the waters, with gusty winds, lightning, and heavy rainfall. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 96 79 94 78 / 20 20 30 10 HARLINGEN 97 74 96 73 / 20 20 30 10 MCALLEN 101 78 99 77 / 30 20 40 10 RIO GRANDE CITY 102 77 99 75 / 30 30 40 20 SOUTH PADRE ISLAND 88 80 88 80 / 10 20 20 10 BAYVIEW/PORT ISABEL 92 77 91 76 / 20 20 30 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...56 LONG TERM....56 AVIATION...69-HEK