Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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607 FXUS64 KBRO 101641 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1141 AM CDT Mon Jun 10 2024 ...New AVIATION... .SHORT TERM... (Today through Tuesday) Issued at 319 AM CDT Mon Jun 10 2024 Key Messages: * Still very warm and humid, but cooler and near seasonable today and Tuesday as Deep South Texas and the RGV get a reprieve from the most intense heat * Moderate to pockets of major HeatRisk today; Moderate with pockets of minor Heat Risk Tuesday * Day-to-day chances for an isolated thunderstorm or two today and Tuesday; 20-40% chance today and 20-30% chance on Tuesday * Outside of thunderstorm chances, favorable marine conditions will continue through Tuesday with light winds yielding light seas The main weather concerns during the short term forecast period will continue to focus on the very warm to hot and humid conditions as well as day-to-day chances for an afternoon/evening thunderstorm or two. Global deterministic forecast models and their ensembles continue to depict the southward advancement of a sfc cold front sagging into central Texas through today. Meanwhile, the 500 mb Sonoran heat ridge which briefly weakened over the weekend, will begin to strengthen/re-emerge over the northwestern parts of Mexico into the 4-Corners region through Tuesday. Given the large-scale setup, our local forecast area will be placed east of the ridge axis and on the leeward side of the strengthening 500 mb ridge. This will result in slightly cooler temperatures (near normal levels) through the short term forecast period as the core of the hottest temperatures (most intense heat) will be located across parts of the western U.S. Despite it still will being very warm and humid across Deep South Texas and the Rio Grande Valley through Tuesday, the slight cool down to more seasonable levels and reprieve from the heat serves as good news for the region. H850 temps sampled between 19-22C will translate to sfc daytime highs in the mid to upper 90s. This coupled with dewpoints (Td) in the mid to upper 70s will result in peak heat indices ranging between 107-113F degrees before a potential sea breeze kicks in later this afternoon. Given that these level temperatures will not persist for more than two hours, a Heat Advisory is not needed. However, a Special Weather Statement (SPS) may be needed for Inland Cameron, Hidalgo, Starr, Inland Willacy, Inland Kenedy, and Brooks Counties today. So slightly cooler than Sunday and cloud coverage will also be key in addition to the timing of the potential sea breeze. The other concern for today is convection potential. Multiple CAMs, global deterministic models and ensembles are signaling for the potential for some isolated showers and thunderstorms developing late this afternoon into this evening. Despite not having a strong shortwave overhead, precipitable water (PWAT) values approaching 2 inches combined with the possibility of a sea breeze developing as winds shift more out of the east could create enough surface convergence in a buoyant environment to break the cap and ignite showers and thunderstorms. Have 20-40% Pops across the region for later this afternoon and evening. The Storm Prediction Center (SPC) has placed the entire area under a General Risk for thunderstorms today. The best timing for any thunderstorms will be between 4-9 PM CDT. Otherwise, expect for rain-free conditions to continue with ideal weather, especially for the beachgoers. Tonight, any left over storms should be winding down giving way to another warm and muggy night. Overnight lows are progged to be in the mid 70s to near 80F. Tuesday will feature a similar setup to today. Still on the leeward side of the aforementioned 594 dam sub-tropical Sonoran heat dome and ridge axis, temperatures will remain closer to seasonable levels. That said, daytime highs are expected to be in the mid to upper 90s. Heat indices are expected to be slightly cooler than today given that dewpoint temperatures (Td) will be slightly lower (under Heat Advisory and SPS criteria). Once again there are some indications amongst computer models that suggest the potential for additional isolated afternoon and evening showers and thunderstorms. PWAT values remain elevated between 1.5 to 2 inches. This coupled with the potential for another sea breeze developing could help to ignite showers and thunderstorms Tuesday afternoon/evening. For now, have 20-30% PoPs for the eastern half of the area (that is Brooks and Hidalgo Counties and points east). The Storm Prediction Center (SPC) has the entire area outlooked once again under a General Risk for thunderstorms on Tuesday. Will continue to monitor trends. Otherwise, expect for rain-free conditions to continue with ideal weather, especially for the beachgoers. && .LONG TERM... (Tuesday night through Sunday) Issued at 319 AM CDT Mon Jun 10 2024 The persistent mid-level ridge returns across Texas through the remainder of the long term period, while broad low pressure settles across the Central Gulf. Most model guidance brings a 500mb low and shortwave around the ridge from the panhandle to the Gulf during the week, and generally keep Deep South Texas to the west of the feature, but do increase moisture through the long term with a weak pressure gradient. Robust PWATs between 1.8 and 2 inches begin rolling in each afternoon, generally near to slightly above the 90th percentile for PWATs in mid June. In a light wind regime with increased Gulf moisture, expect the sea breeze to develop every day, clipping highs across coastal counties a little and limiting peak Heat Indices. Highs still reach 95-102 east to west, with lows generally 74-79. Have blended the NBM with NBM50 Thursday into Monday, which keeps highs more in line with recent MOS trends and plays off the easterly to perhaps ENE flow Thursday through Saturday. The only day at the moment to potentially briefly creep back toward Heat Advisory criteria is Monday afternoon across the coastal counties. Overall, the pattern looks very summer-like, with the chance of streamer showers offshore toward the coast each morning and isolated convection along the sea breeze each afternoon. NBM has caught on to the streamer showers maybe a little too well, but not as bullish on the sea breeze. Have nudged offshore and coastal POPs down a little for streamers and bumped inland POPs up each afternoon with the sea breeze, but kept it isolated until confidence improves. && .AVIATION... (18Z TAFS) Issued at 1125 AM CDT Mon Jun 10 2024 An outflow boundary is moving through the CWA from north to south. It should pass to the south in another two to three hours. There has been some convection over northeast Kenedy County and the adjacent coast already, and isolated convection is becoming evident south of the RG. Interaction with the sea breeze is a bit of a wild card right now, but that could also contribute to some storms around the TAF terminals this afternoon. Drier air behind the boundary is clearing things out, which should happen later today after the local convection ends. Other than low clouds thickening ahead of the boundary and supporting MVFR ceilings, VFR will otherwise be expected. There could be some cloud to ground lighting within these afternoon storms. && .MARINE... Issued at 319 AM CDT Mon Jun 10 2024 Now through Tuesday...High pressure and a weak pressure gradient will result in favorable marine conditions today through Tuesday. Light east-southeasterly winds will result in light seas. There is a chance of an isolated shower or thunderstorm developing on during the afternoon/evening hours on both Monday and Tuesday. Tuesday Night through Sunday...A weak pressure gradient maintains generally light southeasterly to easterly flow through the long term period resulting in seas of 2 to 3 feet. Broad low pressure gradually builds across the Central Gulf, increasing the chance of streamer showers and isolated convection through the weekend. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 95 79 95 78 / 30 10 30 0 HARLINGEN 96 76 96 75 / 30 10 20 10 MCALLEN 98 79 99 78 / 40 30 20 10 RIO GRANDE CITY 98 78 98 77 / 20 30 10 10 SOUTH PADRE ISLAND 87 82 86 81 / 30 10 30 10 BAYVIEW/PORT ISABEL 92 79 91 78 / 30 10 30 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...54-BHM LONG TERM....52-Goldsmith AVIATION...54-BHM