Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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606 FXUS64 KBRO 290556 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1256 AM CDT Wed May 29 2024 ...New AVIATION... .SHORT TERM... (Tonight through Wednesday night) Issued at 255 PM CDT Tue May 28 2024 Key Messages: - Heat Advisory in effect through 8 PM. - Slight risk (level 2 of 5) for severe thunderstorms late this evening and tonight. The influence of the mid/upper level ridge will still be present through the short term period, but won`t be quite as strong as it was over the weekend. This will place Deep South Texas in a more favorable region for unsettled weather (as we saw with last night`s storms) through tomorrow as a shortwave tracks over South Texas. The latest radar and satellite imagery depict partly to mostly sunny skies and rain-free conditions across all of Deep South Texas this afternoon. Meanwhile, an MCS continues to track into Southeast Texas after barreling across North Texas early this morning, sending an outflow boundary toward South Texas. A few showers and thunderstorms have developed off of the boundary, but there should be an uptick in coverage as the boundary translates south and encounters a favorable environment for convective initiation. In the meantime, hot and humid conditions will persist across Deep South Texas, with heat indices approaching 111-115 degrees through the early evening hours. In addition to monitoring any convective development along/ahead of the aforementioned outflow boundary, we`ll also need to keep an eye on convection developing along the Sierra Madre late this afternoon into the early evening hours. Well established low level southerly flow has maintained high precipitable water values across the region, with BRO`s 12Z sounding observing a PWAT of 1.75 inches. Similarly, high res guidance maintains similar or slightly higher values tonight into tomorrow. Forecast model soundings indicate the presence of 7-8 C/km mid level lapse rates, MUCAPE values around 2000-3500 J/kg, and bulk shear values around 30-40 knots. All in all, a favorable environment that would support the development of severe thunderstorms with a threat for large hail and damaging winds late this evening and overnight. Initial thoughts are that any convection will reach the Rio Grande Plains after 9-11PM, and track further east toward the I-69 corridor closer to 2-4AM. There is still some uncertainty on the development of any severe thunderstorms tonight, mainly across areas closer to the coast as the environment is slightly less favorable. This will result in a weakening trend as the convection tracks closer to the Gulf waters. Most of the high res guidance is favoring a solution with convection developing off of the Sierra Madre rather than any convection along the outflow boundary, but it is still something to keep an eye on in the evening hours. Low precipitation chances (around 20%) will exist on Wednesday as the shortwave continues to track toward the Mid Texas Coast. Otherwise, another warm day with highs in the upper 90s to around 100 degrees with heat indices ranging from around 105 to 114 degrees during the afternoon hours. A Heat Advisory may be needed for portions of the region, but the potential for isolated to scattered showers and thunderstorms may keep temperatures lower than forecast. Otherwise, low in the mid 70s to low 80s are expected tonight and Wednesday night. && .LONG TERM... (Thursday through next Tuesday) Issued at 255 PM CDT Tue May 28 2024 Key Messages: -Above normal high and low temperatures -Very little rain chances The mid-level ridge continues to be the driving force for the weather for Deep South Texas and the Rio Grande Valley. While the center of the ridge will shift between south of the Baja Peninsula to Central Mexico. This pattern will put the region into a hot and mostly rain free pattern. Temperatures are expected to be above normal with Heat Advisories being needed for almost every day during the long term forecast period. While the heat indices are expected to be in the range of 105 to 114 through the long term forecast period. Friday seems to be a very borderline day on if a Heat Advisory will be needed. Will need to further shifts to continue to monitor how the models handle the heat indices leading up to Friday. Otherwise, Heat Advisories are likely for the inland counties within the CWA. As for the rain chances, while some convection is likely to develop along the Sierra Madre, the questions remains on if those showers and thunderstorms will be able to make into Deep South Texas and the Rio Grande Valley. Models continue to show that the middle and upper levels of the atmosphere are expected to be dry. Along with the mid- level ridge, the atmosphere does not appear to be very favorable for showers and thunderstorms. However, cannot rule out a rouge isolated shower or thunderstorm making its way into the region. Finally, an enhanced pressure gradient will see the surface winds pick up over the region that could result in a Wind Advisory for Cameron, Willacy, and Kenedy counties possibly Saturday through Monday. && .AVIATION... (06Z TAFS) Issued at 1247 AM CDT Wed May 29 2024 A mix of VFR/MVFR conditions and light to moderate east to southeast winds prevail across Deep South Texas early this morning. However, ongoing convection is leading to locally higher wind gusts and lower visibilities. BRO radar shows a line of convection from near Baffin Bay southwestward to near MFE. The movement to this activity was generally to the east. Will mention TEMPO wording for all RGV aerodromes due to the ongoing convection and outflow boundaries. TSRA is expected to end over the next several hours leading to generally VFR conditions. Light east to southeast winds early this morning will increase and become southeast later this morning into the afternoon. && .MARINE... Issued at 255 PM CDT Tue May 28 2024 Now through Wednesday night...Generally favorable marine conditions are expected as light to moderate southeast winds and low to moderate seas prevail. There may be a brief period of Small Craft Exercise Caution conditions Wednesday afternoon, mainly along the Laguna Madre, due to occasional higher wind gusts. Low rain chances will exist tonight and tomorrow. Thursday through Next Tuesday...Moderate southeasterly winds and moderate seas are likely through next Tuesday. With a thermal low over Mexico and high pressure over the Gulf of Mexico, the pressure gradient is going to be enhanced, which will result in Small Craft Exercise Caution. Small Craft Advisories become more likely by Friday and last through the rest of the period. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 81 95 82 95 / 10 10 0 0 HARLINGEN 79 98 79 97 / 10 10 0 0 MCALLEN 80 100 82 99 / 10 10 0 0 RIO GRANDE CITY 79 101 79 100 / 20 10 10 10 SOUTH PADRE ISLAND 82 87 82 88 / 10 10 0 0 BAYVIEW/PORT ISABEL 80 93 81 93 / 10 10 0 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...22-Garcia LONG TERM....64-Katz AVIATION...63-KC