182 FXUS64 KBRO 282336 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 636 PM CDT Wed Aug 28 2019 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...VFR conditions are expected through the TAF period with isolated thunderstorms and tall CB, possibly including hail, staying northwest and west of MFE through this evening. Brief periods of MVFR CIGs are possible again tonight, similar to the past few nights, as lower level clouds stream northwest from the Gulf of Mexico. Any breezy winds this evening decrease after sunset, remaining light until tomorrow afternoon, occasionally gusting above 15 knots. && .PREV DISCUSSION... /issued 333 PM CDT Wed Aug 28 2019/ SHORT TERM (Tonight through Thursday Night): Convection is firing over the Texas Coastal Bend, north of BRO's CWA, as a weak disturbance interacts with the sea breeze. The sea breeze is rather weak in our region but the latest CAM's continue to advertise this disturbance moving into our region late this afternoon and early evening. Deterministic models show the mid- level disturbance moving southwest across the CWA this evening with very limited QPF amounts and coverage. Model sounding do indicate instability waning and a surface inversion setting up, around or after 03Z, while PWATs 1.8 to 2 inches persist. Have expanded low grade pops across the northern Ranchlands and hinted at a few cells possibly moving into the northern portions of the Lower and Mid Valleys, all before 10 pm, if the convection does moves into or materializes over Deep South Texas. Any cells that do form could produce brief downpours. Once this disturbance moves into Nuevo Leon, Mexico later tonight deterministic models do not show any other disturbances on the eastern periphery of the dominate mid-level ridge through Thursday night. As for moisture levels models suggest a slight drying, dropping mean RH levels to below 60 percent and pwats lowering to a respectable 1.5 to 1.7 inches tomorrow afternoon. With this said near zero rain chances for Thursday will continue in the forecast. Temperatures have been a bit slow in climbing today with gradual mixing out of the higher dewpoint from this morning. As a result, heat indices have not fully achieved advisory levels with exception of the Lower Valley where BRO is currently at 113 degrees. In any case, temperatures could climb another 2 to 3 degree the remainder of the afternoon so will hold onto the heat advisory at this time. For Thursday highs will be similar if not a degree or two warmer than today with the slightly drier conditions. Heat indices look to stay below advisory levels, 111-115 degrees, but can not rule out the Lower Valley and Kenedy county seeing an hour or two of 111-112 at peak heating. Minimums to bottom out a few degrees lower tonight and Thursday night with mostly clear skies and light winds but should still remain in the 76-80 degree range. LONG TERM (Friday through Wednesday): 500 mb ridging centered across the southwest US will gradually slide to the east across the central plains during the long term. However, locally, 500 mb heights will begin to gradually lower this weekend and into next week. Anticipate for hot conditions to continue but area temperatures are expected to gradually lower back closer to climatological average levels during next week. Heat index values will peak between 105 to 111 degrees through the weekend before lowering slightly into next week. The combination of light to modest onshore winds with relaxed surface pressure gradient and a pocket of low-level moisture should favor the opportunity for some isolated sea breeze convection for Friday and Saturday. Areal coverage may extend slightly more westward Saturday compared to Friday. Sunday will trend mainly dry, featuring only silent 10% pops, as a pocket of dry air aloft pushes over the region, which is modeled by both the ECMWF and GFS on its latest runs. Dew points will actually drop into the 60s across much of the area with some locales in the mid 50s out west on Sunday afternoon. Early next week will feature a TUTT low with an associated inverted surface trough moving westward across the Gulf of Mexico. This will help to push higher moisture across the region, resulting in higher pops. The Latest models have the low moving west-southwestward closer to Mexico to our south. However, the low will remain in enough of a proximity to keep slight chance to chance pops in the forecast, especially the further south. We'll continue to keep an eye on this feature and its associated moisture with progression throughout the next week. MARINE (Now through Thursday): Broad weak surface high pressure over the Gulf of Mexico is shown to remain in place through Thursday. This will continue to provide a light southeast flow with seas slowly subsided to 2 feet or less. Not expecting any exercise caution wording or SCA's through the Thu night. An isolated shower or thunderstorms may approach from the north later this afternoon and tonight with outer Gulf water being favored Thursday and Thursday night.: Friday through Wednesday: Light to moderate onshore winds will result in low to moderate seas through the long term period. Winds could trend light and variable at times. Winds are to respond to a weak low pressure system advancing westward across the Gulf of Mexico from early to middle of next week. This will result in winds becoming east-northeasterly and for a slight uptick in seas from late Sunday through Tuesday. Otherwise, shower and thunderstorm chances will be on the rise. Locally higher winds and seas are possible with any thunderstorms. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 56/99