275 FXUS64 KBRO 152022 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 322 PM CDT Fri May 15 2020 .SHORT TERM (Tonight through Saturday Night): A 500mb shortwave spins up and strengthens as it crosses the state of Texas today before settling into East Texas on Saturday. The bulk of local weather will largely depend on what occurs north of us. The morning sounding at BRO showed CAPE values over 4000 j/kg, DCAPE values topping 1000 j/kg with steep mid level lapse rates above 7 C/km and strong enough shear for rotating updrafts. It also showed a moderate to strong elevated cap, knocking the severe threat down to a low murmur. Model soundings across Zapata and Starr counties, however, are much more favorable for damaging winds and large hail. DCAPE across Zapata this afternoon jumps to over 1800 j/kg with shear topping 30 kts early and 50 kts later this evening. SHIP values sit above 2.0 through the late afternoon, growing confidence in a large hail threat. The best timing seems to be early this evening across northern Mexico, gradually working toward the border. The threat for large hail may give way to damaging winds by early tonight as most CAMs show a line of convection working southward through late tonight. If this happens, the chance of rain may drop off rather quickly as the atmosphere stabilizes behind the line, leaving Saturday convection somewhat in doubt. Model soundings develop another round of storms near CRP late Saturday morning, with convection working southward through Deep South Texas into Saturday afternoon. Again, this would generally be a hail to damaging wind threat and strongly depend on what happens late tonight and north of our CWA early tomorrow afternoon. PWAT values between 1.8 and 2.1 inches will continue the locally heavy rainfall threat tonight into Saturday, although most convection is expected to generally move a little quicker, likely limiting some flooding concerns. Temperatures are expected to be above normal today and near normal Saturday with breezy southeasterly winds today. .LONG TERM (Sunday through Friday): As the 500 mb trough exits TX Sun, ridging will be building in pretty quickly over the state stabilizing the atms steadily. The 500 mb ridging will then likely build in amplitude as two closed lows form up over the West Coast and the mid Atlantic States through Wed. The West Coast 500 mb low will then open up and will lift out to the NE Thur and Fri. This will in turn erode the 500 mb ridging over the western Gulf. Even though the 500 mb ridging does weaken over time somewhat, am sceptical that this will result in much of a difference in the overall temperature regime. Will lean closer to the warmer side of guidance throughout next week. Some residual moisture will be present over the RGV on Sun and Mon allowing for some slgt chc/chc pops lingering over the region both days. But the overall longer term conv chcs will be pretty minimal after Mon. Will go with silent pops <10 % from Tues onwards. The ECMWF and GFS models are in pretty decent agreement in the overall 500 mb fields. The main difference between the two models is the placement of the 500 mb closed lows bracketing the ridge axis over the RGV. The GFS has a more northward placement of these two features versus the ECMWF. Otherwise, overall confidence in the longer range forecast wording is above average for both temps and pops. && .MARINE (Now through Saturday Night): Low pressure develops and deepens across central Texas, strengthening the pressure gradient across the lower Texas coast this afternoon into this evening. Southeasterly winds and increasing swell are expected to deteriorate marine conditions into Saturday morning, with Small Craft Advisories possible across the Gulf. Small Craft Advisories may be needed across bay waters this afternoon and evening. Thunderstorms are possible late this evening through Saturday afternoon, especially across northern Gulf of Mexico waters. Damaging winds and frequent lightning are expected. Sunday through Wednesday Night: The PGF looks to remain pretty weak over the lower TX Bay and Gulf waters next week as weak surface ridging remains in control over the area. No SCA conditions are expected for either the lower TX Bay or Gulf waters throughout mid week next week as a generally light onshore flow pattern prevails through Wed. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 79 89 76 86 / 50 50 20 30 BROWNSVILLE 80 90 76 93 / 40 50 20 20 HARLINGEN 78 91 75 93 / 50 60 20 20 MCALLEN 78 93 76 94 / 40 50 10 20 RIO GRANDE CITY 77 94 75 97 / 50 40 10 20 SOUTH PADRE ISLAND 79 84 78 82 / 40 50 20 30 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV Short Term/Aviation...56 Long Term...60 IDSS...67