####018007218#### FXUS64 KBRO 140010 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 710 PM CDT Mon May 13 2024 ...New UPDATE, AVIATION, MARINE... .UPDATE... Issued at 650 PM CDT Mon May 13 2024 Severe Thunderstorm Watch 238 has been expanded to cover all of Deep South Texas including Hidalgo and Cameron and Willacy Counties. Also, South Padre Island and the adjacent coastal waters are within the Severe Watch Box. The storms are propogating east and will be approaching the Mid and Lower RGV between 6:15 and 8 PM. && .SHORT TERM... (Tonight through Tuesday night) Issued at 315 PM CDT Mon May 13 2024 Key Messages: -Hot temperatures today with a Heat Advisory until 7 PM. -Strong to severe storms will be possible later tonight. First up, let's talk heat. Southerly flow and 850mb temperatures of 23C-25C will allow for temperatures this afternoon to reach mid 90s. The hot temperatures combined with high humidity will make "feels like" reach the triple digits. We currently have a Heat Advisory out until 7 PM CDT for inland Kenedy, inland Willacy, inland Cameron and Hidalgo counties. Heat indices could reach 114 degrees. A weak cold front will move through Deep South Texas on Tuesday which will help keep temperatures a few degrees cooler. With that said, its still going to be hot with highs in the 90s for most of the region. Humidity levels will not be quite as high, so while heat indices are still expected to reach the triple digits (mainly along the river) we are not looking at Heat Advisory conditions for Tuesday. Now, let's talk rain and thunderstorms. We had a round of scattered rain showers and thunderstorms this morning which have all moved out of the area. As we head into later this afternoon into this evening we could get another round of thunderstorms. This activity has the potential to be more robust, thanks to building instability through this afternoon. CAMs models are beginning to come into better agreement with a line of thunderstorms over the CRP CWA and moving southeast through the afternoon and begin to push into the northern Ranchlands as early as 22z. These storms will continue to move southeast through the evening. Some of this activity may be strong to severe. Main threats will be large hail, with CAPE values across the CWA exceeding 3000 J/kg and lapse rates around 7.5C, and high wind gusts in excess of 60 mph. Brief heavy rainfall and frequent cloud to ground lighting will also be possible with this activity. The SPC has portions of Kenedy, Brooks and Jim Hogg counties in a SLIGHT risk for severe weather (2 out 5) and the remainder of the CWA in a MARGINAL risk (1 out of 5) of severe weather. This activity should move out of the region by around midnight. && .LONG TERM... (Wednesday through next Monday) Issued at 315 PM CDT Mon May 13 2024 The upper-level flow over South Texas looks to be generally south westerly for the start of the long term period. An upper level trough looks to move through the region Friday and Saturday, making way for an upper-level ridge to build into the area near the end of the period. A couple of shortwaves moving through the upper-level flow could enhance forcing over Deep South Texas Wednesday, Thursday, and Friday Afternoons. At the surface, easterly winds are expected to shift southeasterly Wednesday, transporting additional moisture and warmer air to the region. A surface low looks to develop over North Texas on Friday, with a cold front stretching southwesterly across Central Texas. This cold front is expected to drop southeast through the day Friday, possibly reaching Deep South Texas Friday afternoon. This cold front looks to be fairly weak by the time it reaches Deep South Texas, and will likely only reduce temperatures a couple of degrees. Winds look to briefly shift northeasterly behind the front Friday evening, before shifting back to the southeast by Saturday afternoon, allowing warmer air and additional moisture to mover into the area through the remainder of the period. Rain chances through the period have trended downwards with the latest guidance runs. The best chance for rain looks to be Friday, ahead of the cold front, but that is only about a 10-20% chance. The primary threat looks to be heat, with heat index values forecast to reach 111-115 Thursday and Friday afternoons for the eastern two thirds of the CWA. Heat Advisories will likely be needed both days. Additional heat advisories may be needed for the eastern counties Saturday and Sunday, though conditions look to be more borderline. && .AVIATION... (00Z TAFS) Issued at 650 PM CDT Mon May 13 2024 MVFR ceiling to increase in coverage overnight and persist through mid-morning Tuesday. VFR is expected Tuesday afternoon. Deep Convection moving through Deep South Texas may impact the 3 regional airports between 01-04Z. There is a severe thunderstorm watch out unitl 03Z. && .MARINE... Issued at 650 PM CDT Mon May 13 2024 Strong to severe thunderstorms to move through all the coastal waters through at least 05Z. There is a severe thunderstorm watch out for the Laguna Madre and the nearshore waters until 03Z. && .MARINE... Issued at 315 PM CDT Mon May 13 2024 Tonight through Tuesday night..Generally favorable conditions are expected on the waters off the lower Texas coast through much of the forecast. The caveat will be later this afternoon into tonight as a line of strong to possibly severe thunderstorms moves moves southeast. This activity could produce large hail and strong winds will lead to localized hazardous marine conditions. The best timing for the potential for severe weather will be from 22z to 00z. Showers and storms exit the region by daybreak with a cold front moving southward through the day on Tuesday. Wednesday through next Monday...High pressure across the Gulf will generally keep winds and seas light to moderate through the period. The exception looks to be Wednesday and Thursday afternoons, where an upper-level shortwave looks to enhance surface low pressure over northern Mexico, strengthening pressure gradients along the coast, and briefly increasing wind speeds. Small Craft Should Exercise Caution headlines will likely be needed both afternoons. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 95 78 92 76 / 20 20 10 0 HARLINGEN 98 75 92 73 / 20 20 10 0 MCALLEN 100 77 96 76 / 10 20 10 0 RIO GRANDE CITY 102 75 97 74 / 10 10 10 0 SOUTH PADRE ISLAND 85 79 84 78 / 20 20 10 0 BAYVIEW/PORT ISABEL 93 77 87 75 / 20 20 10 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Heat Advisory until 7 PM CDT this evening for TXZ251-253>255-353. GM...None. && $$ SHORT TERM...68 LONG TERM....60 AVIATION...59-GB