Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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052 FXUS64 KBRO 061753 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1253 PM CDT Thu Jun 6 2024 ...New AVIATION... .SHORT TERM... (Today through Friday) Issued at 332 AM CDT Thu Jun 6 2024 Key Messages: * Continued Hot Today and Friday with Record to Near Record-Breaking Temperatures Developing This Afternoon * Heat Advisory in effect from 1PM-8PM CDT today for All of Deep South Texas and the Rio Grande Valley with the exception of the island counties * Major HeatRisk (level 3 of 4) continues * Marine Conditions become More Favorable Tonight into Friday along with Very Low Rain Chances The main weather headline through the short term forecast period will continue to be the heat. According to the latest large-scale 500 mb upper air analysis, the local forecast area is on the eastern edge a heatwave taking place over the western U.S. as a massive and anomalously strong 591 dam heat dome is situated over the Desert Southwest. Deterministic forecast models/ensembles show this heat dome shifting eastward over Texas on Friday, however, in a somewhat weaker state as the heatwave/500 mb pattern out West breaks down slightly thanks to periods of shortwave energies/impulses helping to compromise the pattern a bit. That said, strong differential surface heating with a strong ridge overhead will increase dewpoint depression and allow for any low level clouds to scour out by this afternoon. With 850 mb temperatures sampled between 23-26C, 1.5 to 2.5 STDEVs above normal, sfc temperatures will have no trouble climbing once again into the upper 90s to lower 100s across Deep South Texas and the Rio Grande Valley this afternoon. Marry this with dewpoint (Td) temperatures in the mid to upper 70s, and heat indices will range from 109-116F this today. Given the situation, a Heat Advisory has been issued for all of Deep South Texas and the Rio Grande Valley with the exception of the island counties of Cameron, Willacy, and Kenedy from 1PM-8PM CDT today. Inland Cameron, Willacy, Kenedy, Counties along with Brooks, Hidalgo, and Starr Counties are areas that are expected to see the highest heat indices. Lastly, the expected high temperatures later this afternoon are expected to be record or near record-breaking. Brownsville and Harlingen have the best chances for either tying or setting a new record today (see Climate Section below). Tonight will feature another warm and muggy night with overnight low temperatures in the mid 70s to near 80F degrees. Narrowing dewpoint depressions given the copious amounts of low level moisture tonight, will allow for low level clouds to increase in coverage once again. Friday will feature another very warm to hot day, though not as hot as today given that the aforementioned heat dome/500 mb pattern weakens some (as highlighted above earlier). Humidity levels are not expected to be as strong as today neither. That said, max heat indices will be weaker on Friday than today with values ranging from 103-111F. && .LONG TERM... (Friday Night through Wednesday) Issued at 332 AM CDT Thu Jun 6 2024 The center of broad 500 mb high pressure will migrate from the Lone Star State, to the north-central Gulf of Mexico, and then to northwest Mexico, but will remain the dominant weather feature over the BRO CWFA. Although dry weather will prevail through a majority of the period, isolated convection is possible Monday and Tuesday, but confidence in this occurring is not high at this time. Temperature-wise, well above normal daytime highs will continue to be the norm. However, slightly cooler values, when compared to recent trends, will result in a HEAT ADVISORY not anticipated each day, with heat indices more likely to be discussed in a daily SPECIAL WEATHER STATEMENT. && .AVIATION... (18Z TAFS) Issued at 1243 PM CDT Thu Jun 6 2024 Persistent smoke/soot from the last of agricultural burning in southeast Mexico...as well as Central American wildfires...combined with increasing low level inversion(s) and lighter winds associated with surface high pressure ridge settling over the Valley have brought back visibility-reducing haze/smog that was fairly thick this morning as pockets of IFR visibility developed. That, along with potential for IFR ceilings...is the primary concern for the overnight. Persistence, therefore, is the best option for the overnight and early Friday morning forecast. After the usual brief uptick in easterly winds late this afternoon/early this evening, which should keep haze at bay, expect haze to return as winds lay down soon after sunrise. Despite a bit more easterly component aloft (as well as across the smokier areas to our south), stagnant air is still here (note another day of "Unhealthy" air quality) so have lowered visibility to the edge of IFR (3 statute miles) especially for the Lower Valley terminals, mainly after 1 AM. Ceilings will form up as well but there is some uncertainty on the duration of such...and exactly how low they drop to. High IFR/low MVFR seems the best bet (900 to 1500 feet) which should continue through 8 or 9 AM...then lift to high MVFR/low VFR to close out the forecast window. Winds will increase a little but still remain below 10 knots through late morning. This should be enough to improve visibility but not by too much...and would not surprise to see 6 miles continue through lunchtime. && .MARINE... (Today through Friday) Issued at 332 AM CDT Thu Jun 6 2024 With the aforementioned 591 dam sub-tropical ridge moving overhead, marine conditions are expected to become more favorable tonight and Friday. Light to moderate winds and seas today will give way to light seas tonight into Friday. A moderate risk for rip currents is expected today. However, the risk becomes a low risk for rip currents tonight and on Friday. (Friday Night through Wednesday) Light to moderate winds and low to moderate seas will occur along the Lower Texas Coast through the period with high pressure in control over the western Gulf of Mexico. Neither Small Craft Should Exercise Caution nor Small Craft Advisory are anticipated to be needed. && .CLIMATE... Issued at 332 AM CDT Thu Jun 6 2024 Record Highs for today June 6, 2024 Brownsville 98F in 2018 (Forecast High is 99F) Harlingen 100F in 2019 (Forecast High is 100F) McAllen 103F in 2018 (Forecast High is 101F) && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 98 79 97 79 / 10 0 10 0 HARLINGEN 100 76 99 75 / 10 0 10 0 MCALLEN 101 79 101 78 / 20 0 10 0 RIO GRANDE CITY 100 78 101 76 / 10 10 0 0 SOUTH PADRE ISLAND 88 81 88 81 / 10 0 10 10 BAYVIEW/PORT ISABEL 94 79 93 78 / 10 0 10 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Heat Advisory until 8 PM CDT this evening for TXZ248>255-351- 353>355. GM...None. && $$ AVIATION...52-Goldsmith