Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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416 FXUS64 KBRO 290831 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 331 AM CDT Mon Apr 29 2024 ...New SHORT TERM, LONG TERM, MARINE... .SHORT TERM... (Today through Tuesday) Issued at 324 AM CDT Mon Apr 29 2024 The start of the short term forecast is expected to be a bit similar to the last several days, with warm and humid conditions. The difference for today however, is that the onshore flow is not expected to be as strong. With a zonal flow aloft set up for the majority of the short term forecast period and a weak mid-level ridge starting to inch in at the end of the period. The upper level synoptic flow is not the best for any sort of development for showers and thunderstorms. While SPC still does have Deep South Texas and the Rio Grande Valley in a general thunderstorm outlook with a sliver of Zapata County in a Marginal Risk (level 1 of 5) for today. Tomorrow they have the entire region in just a general thunderstorm outlook. While the onshore flow will help bring in some low-level moisture, and while there is also plenty of MUCAPE with values over 3000 J/kg. The biggest hindrance to the growth of showers and thunderstorms is the dry air in the middle to upper levels of the atmosphere. Another factor is that the forecast soundings for the region still show a cap persisting into the afternoon as well. While the conditions are not favorable, not going to rule out a stray shower or thunderstorm popping for a short period of time. Thus, rain chances for the short term period are in the range of 20 to 30 percent. As for temperatures, thanks to the onshore flow, the warm temperatures are expected to persist through the period. The high temperatures for today and tomorrow look to be in the 90s for most of Deep South Texas and the Rio Grande Valley. While along the coast and on the island the high temperatures will be in the upper 80s. While some low-level clouds might be present during the morning hours, they are expected to mix out before the day time heating really gets going during the afternoon. As for the low temperatures, all of Deep South Texas and the Rio Grande Valley will be in the 70s. Finally, the High Risk of Rip Currents has been extended once again, as the swell period of 8 seconds and wave heights around 5 feet look to persist for the next 36 hours. Swell period looks to be remain elevated as long as the high pressure over the Gulf of Mexico for the next couple of days until the said high pressure weakens allowing for the winds and seas to come down over the Gulf of Mexico. && .LONG TERM... (Tuesday night through Sunday) Issued at 324 AM CDT Mon Apr 29 2024 Synoptic pattern has not varied much over the last few model runs with a quasi-zonal flow over much of the CONUS this week. The northern side a subtropical ridge edges into South Texas while farther north an elongated trough will pass west to east over the Northern Rockies to the Great Lakes. The subtropical ridge to provide above normal temperatures for much of the week with model guidance still indicating amonalies of 3 to 8 degrees for highs and lows which translates to highs in the 90s and lows in the 70s. Dew points remain high elevating after heat indices 100-107 each afternoon. The most dangerous heat days look to be Thursday and Friday where the probability of heat indices greater than 105 degrees are low to medium or 20-50%. A steady state moderate pressure gradient between ridging over the Gulf and low pressure across the Southern Plains maintains daily breezy to occasional windy conditions. On average the region can expect to see daytime breezes in the 15-25 mph range with Wednesday and Thursday looking like the windiest days Rain chances continue to be limited through the work week with isolated convection still in the offering Wednesday and Thursday with some added moisture depth working with a weak disturbances in the westerly flow. Better chance continue to be indicated Friday and Saturday as sufficient moisture pools in advance of a frontal boundary moving into Central or even Southcentral Texas. PoPs remain low across the board, 20-40 percent with best chances west of I-69C. && .AVIATION... (06Z TAFS) Issued at 1227 AM CDT Mon Apr 29 2024 Mostly MVFR conditions are expected through the TAF period at all TAF sites. A break in the MVFR conditions is likely during the afternoon at the TAF sites as clouds are expected to become more scattered over the region. There is also a possibility of IFR conditions as low-level stratus moves over BRO and HRL around sunrise, but those low-level clouds are expected to move out of the region by mid-morning. Light to moderate winds will continue to be out of the south to southeast, but will gradually shift more towards the east during the day on Monday. && .MARINE... Issued at 324 AM CDT Mon Apr 29 2024 Today through Tuesday..Conditions over the waters are expected to continue to improve during the day as the winds start to weaken. Light to moderate onshore flow with moderate seas is the expected trend through Tuesday. Isolated showers and thunderstorms are possible through Tuesday and may cause locally elevated winds and seas. Tuesday through Sunday: A static weather pattern will maintain a moderate pressure gradient for the remainder of the week and into next weekend. Weaker surface ridge extending over the Eastern Gulf to combine with lower pressure over NE Mexico and West Texas provide moderate onshore winds and a steady state sea state of 4 to 6 feet. This should be maintain periodic small craft caution wording for most of the week. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 91 77 89 77 / 20 10 20 0 HARLINGEN 92 74 92 74 / 10 10 20 0 MCALLEN 94 76 93 77 / 10 10 20 0 RIO GRANDE CITY 95 74 93 75 / 20 10 20 0 SOUTH PADRE ISLAND 81 76 81 76 / 10 10 20 0 BAYVIEW/PORT ISABEL 87 74 87 74 / 20 10 20 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...High Rip Current Risk through Tuesday evening for TXZ451-454-455. GM...Small Craft Advisory until 7 AM CDT this morning for GMZ150-155- 170-175. && $$ SHORT TERM...64-Katz LONG TERM....59-GB AVIATION...64-Katz