897 FXUS64 KBRO 101739 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1239 PM CDT Mon Jun 10 2019 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...VFR categories are expected outside of convection today, with light northerly flow persisting through the period in the wake of a weak cold front. The main challenge will be pinpointing shower and thunderstorm development. A few cells have indicated lightning between BRO and HRL, so will maintain VCTS with TEMPO for TSRA. This will expand towards MFE later this afternoon with conditions trending downward. A few strong storms cannot be ruled out, with MVFR to IFR conditions and possibly even some small hail. Activity should wane overnight with increasing activity by mid-morning on Tuesday. && .PREV DISCUSSION... /issued 552 AM CDT Mon Jun 10 2019/ DISCUSSION...Updated for latest aviation discussion below. AVIATION...A mix of MVFR and VFR conditions continue until VFR takes control by mid to late morning. A cold front has shifted winds out of the north, possibly picking up slightly for the afternoon before becoming light and somewhat variable late tonight again. Thunderstorms are expected to form this afternoon across portions of the valley, with most models favoring MFE over BRO or HRL. Any thunderstorms that develop may contain frequent lightning, gusty winds, hail, and heavy rainfall with tall CB. Rain chances continue overnight, although confidence is higher for thunderstorms across points west of the mid or lower valley. A stray thunderstorm cannot be ruled out. PREV DISCUSSION... /issued 340 AM CDT Mon Jun 10 2019/ SHORT TERM (Now through Tuesday): The ridge of high pressure has settled slightly more west, as anticipated, allowing a front to march south this morning, and will allow mid level disturbances to ride the eastern edge of the ridge south through Texas during the short term period. The approaching cold front will bring a northerly wind shift around sunrise to the RGV, picking up slightly this afternoon. This will help displace the heat that has been stuck across Deep South Texas through the weekend. High temperatures today will drop 5-10 degrees cooler than Sunday, and much closer to normal, in the low to mid 90s. With increasing moisture and instability aloft, a chance of much needed rain returns across most of the area today through Tuesday. Convective models show some light and isolated development near sunrise, otherwise, develop heavier showers and thunderstorms north of the RGV early this afternoon and increase in coverage south through the valley by mid to late afternoon. Any thunderstorms would likely contain locally heavy rain, frequent lightning, and small hail. Have kept severe wording out of the package, but an isolated storm with strong winds or large hail would not be out of the question mid afternoon across RGV. Have left chance wording for showers and thunderstorms through the remainder of the period, as mid level disturbances work south across the CWA through Tuesday. Models take the best chance of rain from west to east Monday night through Tuesday afternoon. Model soundings increase PWAT values to near 2-2.25 inches Monday night into Tuesday, potentially leading to higher rainfall rates. Low lying and poorly draining areas may see nuisance flooding during persistent heavy showers or thunderstorms. With increased cloud cover and better rain chances, have dropped temperatures a couple of degrees for tonight and again for Tuesday afternoon. LONG TERM (Tuesday night through Sunday): Scattered convection will linger across the area Tuesday night through Wednesday in the wake of a previous cold front. Weak east to southeast onshore flow will prevail. The cloudier, rainier interlude will provide a brief window of slightly lower, though still near normal, max temperatures on Wednesday and even Thursday, however temperatures will already start to drift up again around mid week as the mid levels start to dry out, especially inland west. Heat index values will start pushing above the century mark again in earnest Friday through Sunday afternoons. While 100 to 105 degree heat index values will occur on Friday, values of 105 to 110 degrees or more will be possible. The ridge that was previously over the area will consolidate with West Coast ridging around mid week, with a short wave trough moving west to east over the Plains. Plains high pressure will push south into Texas Wednesday night into Thursday, but the impact should be minimal. Once this high pressure shifts east, local winds will veer more to southeast, and the southern portion of the western ridge will edge east even as short wave troughs move through the flow to the north. Rain chances will diminish going into the weekend as heat returns to the area. MARINE: Now through Tuesday: A cold front works south through the lower Texas coast this morning, with northerly winds picking up slightly this afternoon. At this point, do not expect strong enough winds with the front or during this afternoon to be concerned with marine hazards. Mariners can expect a moderate chop on the bay this afternoon, with Gulf seas generally 2-4 feet through Tuesday. Thunderstorms are possible this afternoon and again Tuesday afternoon. Tuesday night through Friday night...Light to moderate east winds and low to moderate seas will prevail from Tuesday night through Thursday, with unsettled weather in the vicinity of an old frontal boundary. Winds will shift to southeast on Thursday night, and begin to strengthen on Friday, with building seas Friday into the weekend. Small craft advisory conditions will be possible Friday night. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 65