086 FXUS64 KBRO 232330 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 630 PM CDT Fri Sep 23 2022 ...New AVIATION... .SHORT TERM... (Tonight through Saturday night) Issued at 236 PM CDT Fri Sep 23 2022 Mid-level ridging centered over Texas will provide large scale subsidence across much of Texas. However, the northern tip of a 500mb inverted trough, also evident at 700mb, moving from east to west over the Southwest Gulf of Mexico will cut under the ridge as it heads toward the Northeast Mexican Coast. The trough, along with enhanced moisture over the Gulf, will support an increase in local convection during the short term. This may result in a slightly enhanced sea breeze on Saturday. In essence, deeper moisture will surge into the region tonight and Saturday with PWATs between 1.5 and up to 2.0 inches in the more aggressive models. Isolated to scattered showers and thunderstorms will develop across the Gulf waters tonight and try to push inland on Saturday, but there will still be a mix of clouds and sun for the day. Forecast QPF amounts are looking rather unimpressive, with some coastal areas of Kenedy and Willacy Counties mustering a couple tenths of an inch of rain accumulation in any given six hours, but most areas will see less. At the surface, broad high pressure across the Gulf of Mexico will maintain light to moderate east to southeast winds. Temperatures overall will trend slightly above normal in the short term with a mix of clouds and sun. High temps on Saturday will range from the 80s at the beaches, the lower 90s near the coast, and the mid to upper 90s farther inland. Overnight low temps will generally decrease into the 70s, except around 80 at the beaches. Patchy shallow ground fog will be possible around daybreak Saturday, especially inland and across the Northern Ranchlands. In the short term, rip current risk will remain low, and there will be no heat or fire weather concerns. && .LONG TERM... (Sunday through next Friday) Issued at 236 PM CDT Fri Sep 23 2022 A Weakening inverted trough over northeast Mexico and limited moisture values with light east-south flow to support a continued chance of showers and thunderstorms Sunday. This weakness aloft pretty much dissipates Monday leaving us to look upstream for our next potential for rainfall. Strong mid-upper trough moving into the Great Lakes and Ohio Valley early next week will send the first cold front of Fall season to south Texas, albeit not very strong. A pre-frontal low pressure trough in advance of the front Monday and the cold front itself Tuesday to trigger isolated to scattered showers and thunderstorms as moisture charts show a deepening of moisture, especially near the coast. Much drier air filters into the region in wake of the front cutting off our chances for rain the latter half of next week. As for the Tropical Depression 9, the upper trough to our north and the cold front passage is likely to protect the western Gulf and the RGV from any significant direct impacts. Minor coastal impacts of coastal flooding coinciding with astronomical high tides next Tuesday through Thursday and some higher swells over the Gulf waters is all that we anticipate from this system. For sensible weather, the circulation of the tropical cyclone looks to combine with the surface high building in behind the front to enhance the dry air intrusion as northeast flow strengthens. Models are suggesting dew points dipping into the 40s and 50s by mid-week which will make these humid days as of late a thing of the past. Temperatures and humidity will be elevated Sunday through Monday with lows in the 70s and highs in the 90s. Heat indices still pushing the lower 100s. In wake of the front high temperatures are not expected to be that much cooler with upper 80s to lower 90s but as mentioned daytime humidity will be much lower in the 20-40 percent range Wednesday and Thursday. Low temperatures will be the most noticeable as dew points fall minimums are shown to bottom out in the low to mid 60s, but would not be surprised to see some upper 50s inland over the open ranchlands Thursday and and Friday mornings. && .AVIATION... (00Z TAFS) Issued at 621 PM CDT Fri Sep 23 2022 VFR conditions are expected to persist through the next 24 hours. Moderate east-southeasterly winds will become light and variable overnight before strengthening to become moderate again by midday Saturday. Isolated to scattered showers and thunderstorms will be possible on Saturday, especially along the sea breeze, but due to the limited coverage and low confidence in the timing, have left out any mention of rain or thunder in the TAFs for now. && .MARINE... Issued at 236 PM CDT Fri Sep 23 2022 Now through Saturday Night...Light to moderate onshore winds and low to moderate seas will prevail through the short term. Swell period will center around 5 seconds. Shower and thunderstorm chances will trend higher as tropical moisture returns and the northern tip of an inverted trough aloft moves overhead. Sunday through Wednesday: Fair marine conditions are forecast through at least Monday, outside of any isolated thunderstorms. Weak high pressure over the northern Gulf of Mexico supports a slack pressure gradient with a continuation of light winds and slight seas. An approaching cold front Monday night with a weak passage Tuesday morning turns the winds northeast at moderate speeds. Tropical Depression 9, currently over the Central Caribbean, is forecast to enter the Southeastern Gulf early Tuesday as a strengthening Tropical Cyclone and is likely to track over the Eastern Gulf of Mexico Tuesday and Wednesday. Although no direct impacts are expected along the lower Texas coast, a moderate to higher swell train, potentially as high as 7 feet or better, may move into the coastal waters and Tuesday and Wednesday and possibly lingering Thursday. Northeast winds may also be enhanced later Tuesday and Wednesday and looks to reach the higher end of exercise caution levels with some gusts exceeding 20 knots. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 76 93 77 93 / 20 30 20 30 HARLINGEN 73 92 74 92 / 10 30 10 30 MCALLEN 74 95 76 95 / 0 20 10 40 RIO GRANDE CITY 72 96 74 96 / 0 10 0 20 SOUTH PADRE ISLAND 80 88 80 87 / 30 20 20 20 BAYVIEW/PORT ISABEL 76 91 76 90 / 30 20 20 20 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...54-BHM LONG TERM....59-GB AVIATION...69-Farris