FXUS64 KBRO 181945 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 245 PM CDT Sun Apr 18 2021 .SHORT TERM (Now through Monday Night): Temperatures don't get too much cooler than this for mid-April in Deep South Texas. As of 2 PM, temperatures around the BRO CWFA ranged from the lower 60s across the Northern Ranchlands to mid-60s in the Rio Grande Valley. Latest GOES-16 visible satellite imagery shows mid-level cloud cover continuing to thin, especially across the west. So, additional warming will likely occur until sunset. Overall, the short-term is expected to be mostly pleasant and cool across all of Southern Texas. Surface high pressure will settle in over central Texas late tonight and into Monday morning, keeping winds light out of the north or northeast. Model guidance is in very good agreement that temperatures will fall into the low-mid 50s everywhere overnight tonight. That's pretty chilly for mid-April. Went ahead and dropped temperatures a degree or two from the previous forecast package. Of course, this is all dependent on how much cloud cover builds in overnight tonight/early tomorrow morning. As the surface high quickly shifts eastward Monday afternoon, winds will turn more east-northeasterly and another weak inverted trough will try to form along the coast. As a result, cloud cover will increase in the morning and rain chances will increase slightly by the afternoon, especially closer to the trough axis. Very little accumulations are expected, with most of the precip. falling as light rain and/or drizzle. Although clouds should be fairly thick near the coast, clearing skies will likely occur mid-late afternoon across western portions of the CWFA. In response, temperatures may rise to near 80 degrees in Zapata and Starr Counties late in the afternoon. Elsewhere, high temperatures will reach the middle 70s tomorrow. These pleasant temperatures are about 10 to 15 degrees below seasonal averages. Slight rain/drizzle chances will continue along the coast Monday night as the coastal trough sticks around. Slightly warmer temperatures are anticipated Monday night with lows generally in the mid-upper 50 and lower 60s. .LONG TERM (Tuesday through Sunday): A nearly zonal flow aloft will prevail through the period. At the surface, high pressure settles across the Western Gulf of Mexico on Tuesday leading to clearing skies and warmer temperatures. A surge of high pressure and a weak cold front arrives Tuesday night into Wednesday morning. High pressure builds into Texas on Wednesday with temperatures dropping to below normal Wednesday and Wednesday night. A 500mb low/shortwave trough moves over the southwestern CONUS on Thursday as surface high pressure slides eastward across the Lower Mississippi Valley. The pressure gradient will strengthen on Thursday as low pressure deepens across the Plains. Temperatures begin to warm on Thursday as southeast flow returns and moisture advection increases. In addition, a warm front surges northward across the CWA Thursday night leading to above normal temperatures through the rest of the period. Embedded disturbances in the 500mb flow may support some convection across the region Thursday through Saturday. The next cold front is expected to approach deep south Texas on Saturday. The extended period of increasing easterly flow and swell may support coastal flooding concerns later in the week with wave runup into the dunes possible on some narrow beaches. && .MARINE (Now through Monday Night): Adverse marine conditions will gradually improve through the rest of the afternoon and into tonight, as winds and seas subside. A Small Craft Advisory remains in effect for the offshore Gulf waters through 7 PM tonight. Much improved marine conditions are expected beginning overnight tonight through Monday night as high pressure builds in across central and eastern Texas. Winds will veer from the northeast to east through the day on Monday as Gulf seas subside between 2 to 4 feet. Tuesday through Friday: Weak onshore flow and low to moderate seas will continue into Tuesday as high pressure settles across the northwest Gulf. The next cold front arrives late Tuesday night into Wednesday morning bringing another round of moderate to strong northeast winds and elevated seas across the coastal waters. Small craft exercise caution conditions may be needed along the lower Texas coast Wednesday into early Thursday. The pressure gradient strengthens along the lower Texas coast late in the week leading to moderate to strong onshore flow and building seas. Small Craft Advisories may be needed by Thursday afternoon into Friday due to elevated winds and seas. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 57 75 63 79 / 10 20 20 10 BROWNSVILLE 55 76 61 83 / 10 20 20 10 HARLINGEN 53 76 59 83 / 10 20 20 10 MCALLEN 55 76 60 85 / 10 10 10 10 RIO GRANDE CITY 53 77 58 87 / 0 10 10 0 SOUTH PADRE ISLAND 64 70 66 73 / 10 20 20 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Small Craft Advisory until 7 PM CDT this evening for GMZ170-175. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 67-Mejia/63-KC