999 FXUS64 KBRO 280542 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1242 AM CDT Fri Jun 28 2019 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...VFR conditions will generally prevail through the period but did include a tempo for possible MVFR CIGs at MFE around sunrise as short-term model guidance indicate higher potential and areal coverage of low-level cloud cover over portions of the mid-valley and the northern ranchlands. However, still cannot rule out a few MVFR CIGs around sunrise at BRO and HRL as well, but confidence is not as high to have included it into the TAFs. Light to modest east-southeasterly winds will otherwise trend throughout the period. && .PREV DISCUSSION... /issued 641 PM CDT Thu Jun 27 2019/ DISCUSSION...Updated for latest aviation discussion below. AVIATION...VFR conditions expected to continue this evening and through most of the TAF period. Kept MVFR CIGs in the TAF at BRO around and/or slightly after sunrise Friday for a few hours. Cannot rule out a few hours of MVFR CIGs at HRL around the same time-frame, but confidence not high enough to include in TAF. Light southeast winds are expected through the period, with a few afternoon gusts on Friday. PREV DISCUSSION... /issued 359 PM CDT Thu Jun 27 2019/ SHORT TERM (Tonight through Friday Night): Mid level ridge of high pressure continues to weaken, allowing a trough of low pressure to slowly build across the northern Gulf of Mexico. The best chance of rain through the short term period remains mainly along the seabreeze this afternoon and Friday afternoon. Coverage remains isolated and with slightly drier air aloft, most showers or thunderstorms may not last very long. PWAT values sit around normal, just over 1.5 inches. Fog was limited overnight, but may become slightly more persistent over the next night or two. SREF favors Friday night over tonight, with lighter winds over the ranchlands. Adjusted high temperatures slightly today as western temperatures were warming faster than previously expected. Overall, not much change to temperatures over the next couple of days, with low to mid 90s across the RGV for highs and mid to upper 70s for lows. The ranchlands may drop into the low 70s Friday night, bottoming out near the dewpoint. LONG TERM (Saturday through Thursday): The longer range forecast period will be highly dependent on the formation and movement of a broad inverted 500 mb trough axis over the Gulf of Mexico. 500 mb ridging will prevail over much of Mexico and the south central Plains States and the western Atlantic as the weekend approaches. However, a general weakness in the ridging will persist over the next couple of days. Then a 500 mb closed low splits away from the more progressive northern 500 mb flow over the CONUS area and will then drift southwards towards the Gulf of Mex helping enhance the broad weakness over the Gulf. This closed 500 mb low will then drift west and will open up under the base of the ridge reaching the TX coastline this weekend. This inverted trough axis is expected to continue moving westwards reaching the TX/Mex border region on Mon eventually drifting northwards into central and northern TX by Wed/Thurs. As this inverted trough axis moves westwards towards TX, a pretty strong mass of tropical moisture will push westwards also likely edging towards the TX coastline by Mon Night/Tues Morning. This area of moisture will steadily push north and westward over much of the state throughout next week potentially setting the stage for additional rainfall for the Deep South TX and the RGV next week. Since this rainfall is expected to be driven by an upper level atms feature, NHC is not discussing the potential for TC development as longer range models do not show much of an associated surface feature. The GFS and ECMWF models are in pretty good agreement in the handling of the strength and movement of the 500 mb inverted trough over the Gulf of Mex and Tex. Both models maintain the best pops from late next Mon through Tues Night/Wed with the pcpn chcs starting to diminish late next week as the tropical moisture lifts more to the north away from the RGV. The influence of this inverted trough next week will help lower down the temps and associated heat index values. The GFS temps are a bit cooler versus the ECMWF numbers. Although some relief is expected from the excessive heat recently, heat index values will still be fairly elevated ranging in the triple digits throughout much of the extended range period. Overall forecast confidence is above average today for both the expected temps and pops next week. MARINE (Now through Friday Night): Light southeasterly winds prevail through Friday night across the coastal waters as surface high pressure holds. Seas are expected to continue to subside and become favorable into Friday night. Gulf waters calm to generally 2 feet or less heading into the start of the weekend. Saturday through Tuesday Night: As the inverted trough approaches the TX coastline next week, the associated surface PGF will likely remain pretty weak allowing for fairly low winds and seas to prevail. However as the inverted trough axis moves more inland to the north and west of the region, the surface PGF will strengthen somewhat allowing for a little stronger SE surface winds and elevated seas early next week. SCEC/borderline SCA conditions will be possible late Tues mainly for the lower TX Gulf waters. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 62