Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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618 FXUS64 KBRO 170535 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1235 AM CDT Tue Sep 17 2024 ...New AVIATION... .SHORT TERM... (Tonight through Tuesday night) Issued at 236 PM CDT Mon Sep 16 2024 Key Message: -Rain chances will continue to pose a threat for localized areas of minor flooding through the forecast period. High pressure begins to build into Deep South Texas over the next few days, however as this ridge builds we will continue to have some weak impulses along with some leftover boundaries from activity yesterday into this morning. This will be the focus of isolated to scattered activity today, though we are not expecting as widespread coverage today as we saw yesterday. This mornings KBRO sounding indicated a PWAT of 2.50 inches which is near record for the day. With precipitation chances generally between 40 and 60% across the CWA this afternoon, we will continue to be at risk for heavy rainfall with high rainfall rates which may lead to minor flooding with any convection that develops. Areas of the Lower Valley who received rainfall of 2 to 5 inches yesterday will be especially susceptible to flooding and ponding of water on roads and low lying areas. Drivers are urged to use precautions in any showers or thunderstorms and water will rise rapidly on roadways with runoff and the ground already being saturated. Rain chances will taper off overnight, though some showers could redevelop along the coast late tonight/early Tuesday morning. Rain chances will once again increase late Tuesday morning into the afternoon(30-40%). This activity will be more isolated in nature and by the afternoon will be more driven by the sea breeze. Forecasted PWATs will still be above normal, so the threat for brief heavy rainfall with isolated minor flooding will continue in areas that have received multiple rounds of rainfall in the previous days. Temperatures overnight tonight and tomorrow will fall into the mid 70s to low 80s. Tomorrow high temperatures will be a bit warmer with highs in the low 90s. Heat indices will will rise to between 105-110 degrees for much of the region. && .LONG TERM... (Wednesday through next Monday) Issued at 236 PM CDT Mon Sep 16 2024 Global deterministic forecast models and ensembles continue to depict a 591 dam heat dome/ridge building over northeastern Mexico into Deep South Texas through the extended. This has been a trend over the past week of models favoring ridging building over the region. The synoptic and large-scale setup will favor slightly warmer/hotter than normal temperatures during the long-term period with mainly dry/rain-free conditions in place. Atmospheric moisture content will be lower compared to previous days/weeks with precipitable water (PWAT) values between 1.5-2.0 inches. However, it should be adequate enough to support a rogue or isolated chance for a shower or thunderstorm nearly each day. Subsidence, however, with the aforementioned mid-level ridging in place, will help to keep things mostly suppressed during the period. That said, expect for mainly dry or rain-free conditions to prevail through the long-term period with an isolated chance for a shower or storm nearly each day. Temperature anomalies will run slightly warmer/hotter than mid-late September standards through the extended. High temperatures are expected to be in the mid to upper 90s for much of the region and for much of the period. Moderate HeatRisk can be expected for the most part through the extended. There could be areas of major HeatRisk developing, especially in the Wednesday-Friday timeframe. Heat indices are expected to range between 105-115F into Saturday. That said, Special Weather Statements (SPS) to Heat Advisories may be needed during the extended. The weather pattern is progged to break down over the weekend, which will allow for temperatures (the warmth) to relax some. && .AVIATION... (06Z TAFS) Issued at 1228 AM CDT Tue Sep 17 2024 VFR conditions are expected to persist through the TAF cycle at all TAF sites. Light southeasterly winds should continue as well. Some low-level clouds are expected to be in the region, thus skies are expected to range from mostly sunny to partly cloudy. Isolated showers and thunderstorms are possible during the afternoon hours, but confidence was not high enough to include in the TAF package. && .MARINE... Issued at 236 PM CDT Mon Sep 16 2024 Now through Tuesday Night...Generally favorable marine conditions will prevail with light winds and seas around 1 foot. Chances of showers and thunderstorms will continue at times through the forecast period that could lead to locally enhanced winds and seas. Wednesday through Monday....Outside of any convection, favorable marine conditions (light to moderate winds and light seas) are expected to prevail Wednesday through next Monday. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 90 78 94 80 / 50 10 30 10 HARLINGEN 91 76 95 77 / 50 0 30 0 MCALLEN 95 78 99 80 / 50 0 20 0 RIO GRANDE CITY 92 76 96 78 / 40 10 10 0 SOUTH PADRE ISLAND 87 82 90 82 / 30 20 20 20 BAYVIEW/PORT ISABEL 89 78 92 78 / 40 10 20 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...68-McGinnis LONG TERM....23-Evbuoma AVIATION...64-Katz