Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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869 FXUS64 KBRO 181126 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 626 AM CDT Sat May 18 2024 ...New AVIATION... .SHORT TERM... (Today through Sunday) Issued at 325 AM CDT Sat May 18 2024 The short-term forecast period starts today and will mark the onset of another stretch of very warm to hot, humid, hazy, and dry conditions. Latest LAPS/MSAS surface analysis depicts a sfc high pressure system building into the area in the wake of a departed frontal boundary and shortwave. This sfc feature will result in increased subsidence over the region which will yield dry and tranquil weather conditions. As far as the warmth/heat, forecast models and ensembles continue to depict 500 mb geopotential heights rising to between 591-591 dam as a broad, elongated sub-tropical heat dome stretching from the eastern Pacific to the Caribbeans strengthen. 1000-500 mb thicknesses are expected to increase to about 582 dam today and 585 dam on Sunday. With 850 mb temperatures expected to climb to between 22-24C on both days, high temperatures will range from the low/mid 90s to near 100F both today and Sunday. With dewpoints in the 70s, heat indices are expected to range from 100-110F. While heat indices look to fall just below Heat Advisory criteria, the NWS HeatRisk tool suggest that any heat related impacts will be confined to most individuals sensitive to heat. Warm and muggy conditions will continue Saturday night with overnight lows in the mid 70s to near 80F with similar dewpoint values. Some patchy mist/fog is possible along with haze as light winds and copious amounts of low level moisture will result in narrow dewpoint depressions. && .LONG TERM... (Sunday night through Friday) Issued at 325 AM CDT Sat May 18 2024 Mid-level ridging will build over Texas through the period leading to warming temperatures through the period. At the surface, steady southeast winds, breezy at times, will allow for plenty of low-level moisture flow to move into the region and thus keeping the air very humid. The combination of lack of deep moisture and subsidence will maintain rain-free conditions across Deep South Texas through the long term. Temperatures are expected in the triple digits across the Rio Grande Plains Monday afternoon with mid to upper 90s across the rest of the area, except for the 80s near the coast. The triple digits will expand eastward through the week, reaching the I-69c/US 77 corridor on Tuesday. High humidity combined with the hot surface temperatures will lead to "feels like" temperatures exceeding 110 degrees in several locations and Heat Advisories may be needed on Monday. However, Heat Advisories will be more likely Tuesday through next Saturday as the heat indices over 111 degrees are more widespread on those days. The latest NBM suggests that the max heat index at 116 degrees for a few locations Friday and next Saturday afternoon. Thus, a possible Excessive Heat Warnings and Watches might be needed during that time. Overnight temperatures each night will remain warm with lows falling into the upper 70s to low 80s. There is a Moderate to Major risk of heat-related impacts for anyone without effective cooling and/or adequate hydration with heat indices ranging up to around 111 degrees for Monday and Tuesday. By midweek, appears to pose an Extreme heat risk with heat indices 111- 116 degrees across much of Deep South Texas. This level of rare and/or long-duration extreme heat with little to no overnight relief affects anyone without effective cooling and/or adequate hydration. && .AVIATION... (12Z TAFS) Issued at 625 AM CDT Sat May 18 2024 Through 12z Sunday.....Latest surface analysis and satellite imagery reveals clearing skies overhead and to our west as a frontal boundary continues to shift southeast and in its wake a sfc high builds into the region. Latest obs at the terminals indicate mainly VFR conditions with the exception of KHRL (IFR due to ceilings of 800 feet AGL). Through this morning, expect for mainly VFR conditions to take place, though there could be instances of MVFR to IFR conditions. As we shift into this afternoon, expect for VFR conditions to be the dominant/main flight category over the terminals. Later tonight, expect for MVFR conditions to return to the terminals. Light and variable winds this morning will become more east- northeast at 5-10 kts later this morning and afternoon. Later this evening/tonight, expect for winds to trend towards light and variable to calm. && .MARINE... Issued at 325 AM CDT Sat May 18 2024 Today through Sunday: Light to moderate winds will yield low to moderate seas today through Sunday. While marine conditions are mainly favorable through Sunday, there remains a "Moderate Risk" for rip currents along the are beaches through Sunday. Sunday night through Wednesday: Weak to moderate onshore flow with moderate seas of generally 3 to 4 ft will persist through Monday. A locally enhanced pressure gradient could lead to Small Craft Caution conditions on the Laguna Madre and the nearshore Gulf waters each afternoon into the early evening hours, Tuesday through late week. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 92 79 94 79 / 10 0 0 0 HARLINGEN 93 75 95 75 / 0 0 0 0 MCALLEN 97 77 99 78 / 0 0 0 0 RIO GRANDE CITY 98 77 98 77 / 0 0 0 0 SOUTH PADRE ISLAND 85 80 84 80 / 10 0 0 0 BAYVIEW/PORT ISABEL 89 77 89 77 / 0 0 0 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...23-Evbuoma LONG TERM....63-KC AVIATION...23-Evbuoma