Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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009 FXUS64 KBRO 241748 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1248 PM CDT Tue Sep 24 2024 ...New AVIATION... .SHORT TERM... (Today through Wednesday) Issued at 346 AM CDT Tue Sep 24 2024 An elongated mid-level ridge is expected to remain in place over Deep South Texas and the Rio Grande Valley today. A 500mb trough/low will dig southward into the Middle Mississippi River Valley on Wednesday and push the associated cold front into south Texas. In addition, Potential Tropical Cyclone Nine should strengthen to a tropical depression or storm as it enters the eastern Gulf of Mexico. Above normal temperatures will continue through the short term. Highs today and Wednesday are expected to be in the low to mid 90s, except for the 80s along the coast. Heat indices should range between 100 to 107. This is still below the criteria for a Special Weather Statement for elevated heat indices and Heat Advisory. The low temperatures for tonight will fall into the 70s, except around 80 for the beaches. Lastly, while the rip current risk is low today through Wednesday. Wave run up along the beaches could reduce the available beach space down. While not expecting to need Coastal Flood Advisory at this point. A Coastal Flood Statement may be needed around high tide, which is at 2:03 AM Wednesday. && .LONG TERM... (Wednesday night through Monday) Issued at 346 AM CDT Tue Sep 24 2024 By Wednesday night, the NHC forecasts PTC 9 to have strengthened to a hurricane and entered the Eastern Gulf. As the tropical system approaches Florida, it will interact with an upper-level closed low over the Southeastern US. This interaction will shift the closed low to the southwest, into the ArkLaTex region. At the surface, a cold front associated with this system will drop south, moving through the CWA Wednesday night into Thursday morning. PWAT values between 1.5 and 2 inches and CAPE values around 1000 J/kg ahead of the front could support some isolated to scattered showers and thunderstorms Wednesday night and early Thursday morning. Behind the front, a drier airmass and northwesterly flow to westerly flow aloft will keep rain chances near zero through the remainder of the period. High temperatures behind the front arent expected to change much. The highs will be slightly lower Thursday afternoon, topping out in the upper 80s to low 90s, then quickly returning to the low to mid 90s over the weekend. Low temperatures will fall into the mid to upper 60s Thursday night, then gradually return to the low to mid 70s over the weekend. The combination of the frontal passage and the arrival of long period swell from the tropical system in the Eastern Gulf will result in increased wave heights and adverse beach conditions Thursday and Friday. Enhanced rip current risk and minor coastal flooding will be possible at beaches along the Lower Texas Coast. && .AVIATION... (18Z TAFS) Issued at 1248 PM CDT Tue Sep 24 2024 Scattered showers have prevailed across the Lower Texas Gulf waters, but the typical "jump" along the sea breeze has been slow to go. Convective-allowing models as well as global models have been rather bearish for this afternoon...and with limited forcing underneath the upper level ridge this makes sense. So...given low confidence have elected to roll a VCSH for all terminals until the sea breeze passes and stabilizes things. This would be around 2-3 PM in Brownsville and by 4 PM in Harlingen. Added to McAllen as well and maintained through sunset. Otherwise...light winds becoming east around 10 knots post-sea breeze this afternoon before laying to to near calm by mid evening, with skies clearing except for few-scattered MVFR cumulus near Brownsville. As for Wednesday...incoming models are also more bearish on rain chances even though energy arrives from the north via an upper- level trough dipping into the lower/mid Mississippi Valley with associated shear axis running from Louisiana through south Texas by midday. This, combined with any early morning showers sneaking onshore, may be enough to trigger isolated activity for Brownsville/Harlngen after 9 or 10 AM. For now, called it VCSH with periodic MVFR ceilings through 1 PM., with McAllen scattered for now. && .MARINE... Issued at 346 AM CDT Tue Sep 24 2024 Today through Wednesday...Favorable conditions are expected to prevail along the Lower Texas Coast through the period. A weak pressure gradient will support light to moderate onshore flow and low to moderate seas. Isolated showers and thunderstorms are possible through the period and could result in locally elevated winds and seas. Wednesday night through Monday...The NHC forecasts PTC 9 to strengthen to a hurricane as it enters the Eastern Gulf by Wednesday night. Swell from this system will likely arrive Thursday, and combined with the passage of a cold front Wednesday night, this will lead to enhanced seas. Small Craft Should Exercise Caution headlines or Small Craft Advisories may be needed for the Gulf waters Thursday and Friday as wave heights look to reach 6-7 feet. Seas are expected to subside over the weekend, with favorable marine conditions prevailing through the remainder of the period. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 91 77 91 74 / 40 20 40 20 HARLINGEN 91 74 91 72 / 40 10 40 10 MCALLEN 95 78 95 74 / 30 10 30 20 RIO GRANDE CITY 94 76 94 73 / 20 10 30 20 SOUTH PADRE ISLAND 88 81 87 79 / 40 20 40 30 BAYVIEW/PORT ISABEL 89 76 89 74 / 40 40 30 20 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ AVIATION Update...52-Goldsmith