FXUS64 KBRO 211145 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 645 AM CDT Wed May 21 2025 ...New AVIATION... .SHORT TERM... (Today through Thursday) Issued at 350 AM CDT Wed May 21 2025 A weak frontal boundary stalled across northern ranchlands early this morning will move northward as a warm front later this morning. Latest surface observations indicate some patchy fog has developed across portions of the area, but the fog is expected to dissipate by the mid morning. The combination of the weak frontal boundary to the north, a mid- level short wave approaching from the west, and abundant moisture (PWATs around 2 inches) will support a low to medium (20 to 40 percent) chance of showers and thunderstorms this afternoon into tonight. However, there is a low (20 percent or less) chance of rain this morning with the increased moisture content and the frontal boundary across the region. The latest CAMs/guidance suggest that some convection will develop over the Sierra Madre this afternoon and move northeast to east towards the Rio Grande River. The thunderstorms that do develop this afternoon into tonight could have the potential to become severe, with the main threats being damaging wind gusts and hail. SPC has most of Deep South Texas in a Marginal Risk of severe weather for today into tonight. WPC has painted the western portions of the CWA, including Zapata, Starr, Jim Hogg and portions of Brooks and Hidalgo counties, in a marginal risk (level 1 of 4) of excessive rainfall for today and tonight. Rain chances end from west to east late tonight into Thursday morning as the upper level disturbance swings eastward. Otherwise, increase cloud cover should keep temperatures slightly lower today (near normal) with highs in the low to mid 90s, except for the 80s at the beaches. Cloudy and mild tonight with lows in the mid to upper 70s. Highs on Thursday will be a degree or two higher than today. There is a Moderate Heat Risk (Level 2 of 4) for all of Deep South Texas today and Thursday. There is a Moderate Risk of rip currents at local beaches today decreasing to a Low Risk tonight and Thursday. && .LONG TERM... (Thursday night through Tuesday) Issued at 350 AM CDT Wed May 21 2025 Upper-level ridging looks to set up over the Central US Friday and continue through the weekend. This pattern will support generally rain free conditions and a gradual warming trend through the weekend. An upper-level trough looks to work it’s way across the Central Plains early next week, which could drive a cold front south, approaching the area late Monday or Tuesday. With the front pushing south, rain chances and cloud cover look to increase early next week, which could support slightly cooler temperatures early next week. High temperatures look to return to the upper 90s to low 100s over the weekend, before falling to the upper 80s to low 90s early next week. Heat indices look to remain just below Heat Advisory criteria this weekend. && .AVIATION... (12Z TAFS) Issued at 636 AM CDT Wed May 21 2025 A mix of IFR/MVFR ceilings with light northeast to east winds prevail across Deep South Texas early this morning. Will mention a TEMPO until 14Z for IFR ceilings and patchy fog. Ceilings are expected to gradually lift to VFR levels later this morning into the afternoon. There is a medium chance for some convection to move into portions of the area later this afternoon into this evening, especially at MFE. Confidence remains low for convection impacting HRL/BRO at this time. && .MARINE... Issued at 350 AM CDT Wed May 21 2025 Today through Thursday...Buoy020 reported southeast winds around 6 knots with gust of 8 knots and seas near 3.9 feet early this morning. Favorable conditions will prevail along the lower Texas coast through the period with light to moderate east to southeast winds and low to moderate seas. Some patchy fog may develop early this morning over the Gulf waters and Laguna Madre, but will dissipate later this morning. There is a low chance (20 percent) of showers and thunderstorms today and tonight. Thursday night through next Tuesday...Generally favorable marine conditions are expected at the start of the period. Pressure gradients along the Lower Texas Coast are expected to increase over the weekend, supporting stronger winds and seas across the coastal waters. Small Craft Should Exercise Caution headlines may be needed Saturday and Sunday. Light to moderate onshore winds and slight to moderate sea look to return by Monday, with generally favorable conditions continuing through the remainder of the period. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 91 78 92 78 / 20 20 10 0 HARLINGEN 92 75 92 75 / 30 20 10 0 MCALLEN 95 77 96 78 / 30 30 10 10 RIO GRANDE CITY 95 74 96 76 / 40 40 20 10 SOUTH PADRE ISLAND 84 79 85 79 / 20 10 10 0 BAYVIEW/PORT ISABEL 87 76 89 77 / 20 20 10 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...63-KC LONG TERM....60-BE AVIATION...63-KC