Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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942 FXUS64 KBRO 182327 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 627 PM CDT Tue Jun 18 2024 ...New AVIATION... .SHORT TERM... (Tonight through Wednesday night) Issued at 329 PM CDT Tue Jun 18 2024 The short term forecast period will continue to focus on a developing tropical cyclone over the Southwestern Gulf of Mexico (over the Bay of Campeche). Deteriorating weather conditions are expected to take shape through the short term period or through Wednesday night. There are two main threats associated with this system that we will talk about. One is the Heavy Rain and Flood Threat. The other is the Winds and Marine/Beach Hazards or threats. Heavy Rain and Flood Threat: The latest radar and satellite observations show isolated to scattered showers over the region this afternoon. This activity coincides with max sfc based differential heating in addition to the continued influx of deep tropical moisture. As we progress through tonight and into Wednesday, the risk/chance for rain and thunderstorms will increase. The main uncertainty at this point is where exactly the rain bands from this tropical system sets up. Latest forecast models have become slightly more bullish on bringing some of the heavier rain bands south through the day on Wednesday. Showers and thunderstorms will come in waves given the tropical nature of this event. The influx of moisture in the days ahead will almost serve or act like an Atmospheric River (AR) from the Gulf of Mexico into South/Southeast Texas. With precipitable water (PWAT) values sampled between 2-2.5 inches, increasing on the order of +3 to +4 STDEVs above normal, and the integrated water vapor transport (IVT) values on the order of +1 to +3 STDEVs above normal, rainfall rates are expected to be very efficient. That said, flooding is expected especially across flood prone areas (i.e. urban, poor drainage, low-lying areas). Hence, a Flood Watch remains in effect for all of Deep South Texas and the Rio Grande Valley from 1 AM CDT tonight to 1 PM CDT Thursday. Motorist should place to leave early to their destinations, slow down, and do not drive on any roads that become flooded. While the rain threat associated with this tropical system could become hazardous, it will also be very much beneficial for the region. This coming rainfall will address the D0 (Abnormally Dry) and D1 (Moderate Drought) over the region. Area dams and reservoirs will also see improved water levels. Lastly, the year to date deficit across our ASOS/Climate sites will flip from a deficit to a surplus. Following this rain event, grasses are also expected to greenup. Winds and Marine/Beach Hazards: The second threat/hazard aspect from this tropical system will be the winds and marine/beach hazards. Winds from this tropical system are expected to increase out of the northeast with gusts on Wednesday ranging between 30-45 mph (highest near/along the coast). Additionally, increased ocean swells have and will continue to increase wave heights. Hence, we`ve updated the Coast Flood Watch to a Coast Flood Warning. Additionally, we have a High Surf Advisory and a High Risk for rip currents in effect. && .LONG TERM... (Thursday through next Tuesday) Issued at 329 PM CDT Tue Jun 18 2024 Periods of showers and thunderstorms will persist through Thursday and possibly into Friday before finally waning as the aforementioned tropical system weakens and moves away. Reprieve from the rain will be rather brief as forecast models and ensembles are signaling another storm system tracking over the SW Gulf of Mexico. This system similar to this first system could bring another round over rain and thunderstorms to the region next week. Will continue to monitor trends and provide more details in the days ahead. && .AVIATION... (00Z TAFS) Issued at 626 PM CDT Tue Jun 18 2024 Through 00z Thursday.... Aviation Weather Key Messages: * Scattered to numerous showers and storms taper down this evening * Rain/thunder threat increases again tonight and continues through Wednesday * IFR, possibly LIFR cigs/vsbys are possible under any thunderstorms that do develop VFR-MVFR conditions were taking place at the terminals this evening with scattered to numerous rain showers over the region, per the latest scans of the Doppler Radar. After this first wave moves through, things should taper down with VFR-MVFR conditions continuing through the rest of this evening. Tonight, rain/thunder chances and coverage are expected to increase with things peaking between the overnight hours into the afternoon hours on Wednesday. During this time, there will be waves of showers and storms occurring, with some capable of producing very heavy rainfall. Any storms that do move over any of the terminals will have the capabilities of reducing cigs/vis down to IFR or maybe even LIFR levels. Things will gradually taper down Wednesday evening and beyond the 00z period. East-northeast winds 15-22 kts with gusts between 30-35 kts are expected through the 00z TAF cycle. && .MARINE... Issued at 329 PM CDT Tue Jun 18 2024 A tropical disturbance in the Southern Gulf of Mexico is expected to move slowly northward then westward, making landfall in Mexico. A large wind field extending to the north of this system will support high seas as well as the potential for Tropical Storm Force winds. A Tropical Storm Warning remains in place for the Laguna Madre and Coastal Gulf waters. Winds and seas are expected to improve over the weekend, with light to moderate winds and moderate seas continuing through the remainder of the period. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 80 86 82 89 / 90 100 100 100 HARLINGEN 77 86 80 89 / 90 100 100 100 MCALLEN 79 84 79 89 / 70 100 100 100 RIO GRANDE CITY 78 81 79 86 / 50 100 100 90 SOUTH PADRE ISLAND 81 86 84 86 / 90 100 100 100 BAYVIEW/PORT ISABEL 79 86 82 89 / 90 100 100 100 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Tropical Storm Warning for TXZ351-354-355-451-454-455. Flood Watch from 1 AM CDT Wednesday through Thursday afternoon for TXZ248>255-351-353>355-451-454-455. Coastal Flood Warning from 1 AM Wednesday to 1 PM CDT Thursday for TXZ351-354-355-451-454-455. High Rip Current Risk through Wednesday evening for TXZ451-454- 455. High Surf Advisory until 7 PM CDT Wednesday for TXZ451-454-455. GM...Tropical Storm Warning for GMZ130-132-135-150-155-170-175. && $$ SHORT TERM...23-Evbuoma LONG TERM....23-Evbuoma AVIATION...23-Evbuoma