739 FXUS64 KBRO 210604 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 104 AM CDT Tue Jun 21 2022 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...VFR conditions now. Tropical moisture concentrating in the southwest Gulf will surge north today with implications for the TAF sites. Light breezes and a more easterly flow will support a late morning to early afternoon sea breeze. The influx of tropical moisture will support scattered showers and a few embedded tropical thunderstorms this afternoon into early evening. Brief MVFR ceilings will be possible near the coast as the sea breeze gets going. Otherwise, some deeper tropical towers will be possible through the afternoon, with lightning and gusty winds the main threats for the regional TAF sites. && .PREV DISCUSSION... /issued 653 PM CDT Mon Jun 20 2022/ DISCUSSION...Updated for latest aviation discussion below. AVIATION...Visible satellite imagery shows a mix of cirrus and fair weather cumulus across the Rio grande Valley this evening. VFR conditions will continue through the next 24 hours. Breezy east to southeast winds will hang in there for another hour or two before becoming light through the overnight hours...then breezy once again by mid morning. There's a chance that some showers and thunderstorms will develop around the aerodromes on Tuesday as some deeper atmospheric moisture moves into the region, but with confidence in the timing and coverage still on the low side, have continued to include VCSH for now. PREV DISCUSSION... /issued 239 PM CDT Mon Jun 20 2022/ SHORT TERM (Tonight through Tuesday Night): Only a couple of showers indicated on KBRO radar this afternoon, moving east-to-west south of the Rio Grande. Seasonally hot temperatures apparent in local observations as well. Some subtle changes occur late tonight into tomorrow, leading to probably our best chances for rain for the next week. Otherwise, tonight will feature near-normal temperatures and muggy conditions with light winds. Patchy fog (mainly shallow) may again occur, especially for western Cameron, Hidalgo, Brooks, and Jim Hogg counties. Latest WPC surface analysis shows a tropical wave moving into the Yucatan peninsula. GOES-16 precipitable water estimates with this feature are around 2.0 inches. A rather modest upper-level low, apparent on current upper-level water vapor satellite imagery, is straddling the Texas/Coahuila state border (just east of the Big Bend). Both GFS and NAM models sag this feature slowly southward, through the western half of our CWA, over the next 24-36 hours. This should act to pull some of the deeper moisture now pooling over the Bay of Campeche in our direction. Timing of the deeper moisture's arrival now seems to be closer to mid-day Tuesday, so have trended highest PoP's (30-40%) from then until early evening, concentrated along the Rio Grande. Should be enough instability for a few thundershowers as well. Steering flow looks like it will be from the east at 20-25mph, so not expecting any big amounts from the showers/thunderstorms...perhaps a few tenths of an inch with locally half an inch or so. High temperatures on Tuesday should edge down 2- 3 degrees F from today's readings, at least across the mid/Lower RGV, where cloudiness and showers should have higher coverage. Rain chances should wane pretty quickly after sunset tomorrow, as daytime heating is lost and the H25 ridge begins to re-assert itself, with the the aforementioned low moving inland to our south. LONG TERM (Wednesday through Monday): The Long Term period will start off with a slight chance of showers and thunderstorms for Wednesday with the Saharan Air Layer making its way back to the CWA as well. The rain is expected to end by Wednesday evening with the dust and haze sticking around for the next couple of days before disappearing by the weekend. Then, surface ridging dominates the central U.S. allowing our temperatures to steadily increase throughout the week. Currently, the warmest day in the period is expected to be Sunday. Highs are forecast to be in the 105 degree range out west with most of the RGV reaching 100 degrees as well. Heat indices stay under Heat Advisory criteria but will be above average for this time of year. MARINE (Tonight through Tuesday Night): Favorable marine conditions in place for the moment, both along the Laguna Madre and the Gulf waters. Latest report from Buoy 42020 is for ENE winds at 8 knots and essentially flat seas of 1.0-1.5 ft. SE breezes freshen by tomorrow afternoon (to 15-18 knots), as a trough moving into the Bay of Campeche acts to tighten the gradient a bit. Seas build to 4-5 ft. as a consequence, leading to likely Small Craft Exercise Caution (SCEC) conditions extending through Tuesday night. (Wednesday through Monday): Slight chance of showers and thunderstorms on Wednesday with the Saharan Air Layer returning bringing haze for the end of the work week. Intermittent Small Craft Exercise Caution may be needed through Wednesday night. But by Thursday, winds and seas will be low and calm and pleasant marine conditions will persist through the rest of the Long Term period. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 91 77 87 76 / 30 10 10 0 BROWNSVILLE 91 77 93 76 / 30 20 10 0 HARLINGEN 94 75 93 74 / 30 10 10 0 MCALLEN 93 75 94 74 / 30 10 10 0 RIO GRANDE CITY 97 76 95 74 / 20 10 20 0 SOUTH PADRE ISLAND 85 79 85 79 / 30 10 10 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: https://weather.gov/rgv 54-BHM/66-Tomaselli