Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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240 FXUS64 KBRO 142243 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 543 PM CDT Sat Sep 14 2024 ...New AVIATION... .SHORT TERM... (Tonight through Sunday night) Issued at 218 PM CDT Sat Sep 14 2024 Upper level ridging is expected to hold through the short term, which, combined with moist onshore southeasterly flow, has resulted in an increase in temperatures, relative humidity and heat indices, or the `real feel` temperature. This has resulted in a Heat Advisory today for Brooks and Hidalgo counties as well as Inland Cameron, Inland Willacy and Inland Kenedy counties, effective till 5 PM this afternoon as temperatures are forecast to exceed 111 F for at least 2 hours and potentially reaching as high as 114 F degrees. Overnight, remnant moisture from Tropical Storm Ileana, located over the southern Gulf of California and off the western Mexico coastline, will be carried by mid-to-upper level winds over Deep South Texas, bringing scattered to overcast skies. Convection over the Sierra Madre Mountains may spill over the western portions of the County Warning Area (CWA) this evening and into the overnight hours, bringing a 15 to 30% chance of showers and thunderstorms to the upper RGV as well as Jim Hogg and Zapata counties. By the predawn hours and into Sunday morning, vorticity associated with a mid-level shortwave trough, is anticipated to increase over the CWA in a west-to-east fashion, providing a mid-level lifting mechanism for low-level moisture to generate a 40% chance of showers and thunderstorms across Deep South Texas tomorrow morning. By the afternoon, continued vorticity advection is expected to result in numerous showers and thunderstorms, some of which may contain brief and heavy downpours, especially across the Rio Grande Plains and all of the RGV, where POPs could range between 50% to 70% into the early evening hours. WPC QPF totals indicate the potential for 0.25 to 0.75 of an inch of rain across the mid-upper RGV and Rio Grande Plains. However, a few inches of rain is possible within heavier and longer-lasting downpours. WPC has not included any of the CWA within an Excessive Rainfall Outlook, but heavy rain may lead to nuisance flooding in some locations. Overnight, POP`s decrease across most of Deep South Texas, but an isolated chance of showers and thunderstorms remains across the RGV closer to the border. Overnight lows tonight will range from the upper 70s with lower 80s across the RGV and the barrier islands. Temperatures tomorrow will reach into the upper 80s for barrier islands and lower to mid 90s for inland Deep South Texas. Tomorrow night`s lows will keep mostly in the upper 70s with lower 80s along the Gulf coastline. && .LONG TERM... (Monday through next Saturday) Issued at 218 PM CDT Sat Sep 14 2024 Rain chances trend downward but do not go away completely through the long-term. 250-500mb ridge builds and becomes anchored over Texas as large scale mid-upper level troughs set up over the western and eastern portions of the country. A few perturbations in the southwest flow aloft and remnant moisture from Pacific Tropical Storm Ileana should be sufficient to squeeze out a few showers or thunderstorms Monday. Beyond Monday, surface southeast flow maintains seasonal moisture levels providing a slight chance of daily sea breeze showers or isolated thunderstorms. Probability coverage will only be in the 10-20 percent range at best and with the ridge building and more subsidence than lift the sea breeze will have a tough time organizing which will limit convection beyond the coastal counties Wednesday-Friday. Seasonal to slightly above normal temperatures continue to supported by model output with heat indices on the high end but just below heat advisory criteria at this time. Maximums to reach upper 80s at the beach, 90s inland to near 100 for the Rio Grande Plains with 70s to near 80 at the coast should suffice for low temperatures. && .AVIATION... (00Z TAFS) Issued at 539 PM CDT Sat Sep 14 2024 VFR is generally anticipated at the aerodromes through the next 24 hours. A prevailing SHRA has been included in the TAFs for Sunday afternoon, as a disturbance in the middle layers of the atmosphere generates widespread convection. && .MARINE... Issued at 218 PM CDT Sat Sep 14 2024 Tonight through tomorrow night...Ideal marine conditions are anticipated with light to gentle southeasterly winds and low seas. Isolated showers and thunderstorms are possible Sunday morning becoming scattered in the afternoon, lasting into the evening hours followed by a slight chance of showers and thunderstorms. Lightning and enhanced winds and seas are possible within thunderstorms. Monday-Friday...Gentle to light onshore breezes coupled with low seas are expected to persist along the lower Texas coastal waters Monday and Tuesday. Surface pressure gradient remains relaxed with mid-level high pressure build over Texas and surface ridge remaining weak across the Gulf of Mexico. As heat builds inland through the week a moderate onshore flow develops Wednesday-Friday each afternoon impacting mainly the Laguna Madre. Probability for Exercise Caution statement remains below 20 percent Monday and Tuesday, with increasing chances over 50 percent mid to late in the week. Small Craft Advisories probability remains below 10 percent. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 80 90 78 90 / 20 60 40 50 HARLINGEN 77 91 75 91 / 10 60 20 50 MCALLEN 80 94 79 95 / 20 70 30 50 RIO GRANDE CITY 79 91 76 92 / 30 70 40 50 SOUTH PADRE ISLAND 82 87 81 87 / 20 50 40 40 BAYVIEW/PORT ISABEL 78 89 77 89 / 20 50 30 40 && .BRO WATCHES/WARNINGS/ADVISORIES...None. && $$