Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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042 FXUS64 KBRO 171121 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 621 AM CDT Mon Jun 17 2024 ...New AVIATION... .SHORT TERM... (Today through Tuesday) Issued at 304 AM CDT Mon Jun 17 2024 This portion of the total forecast is expected to be the start of the much-discussed and much- anticipated significant precipitation event for Deep South Texas and the Rio Grande Valley. The latest Tropical Weather Outlook from the National Hurricane Center lists a 60% chance of tropical formation over the southwestern Gulf of Mexico through the next 48 hours, and a 70% chance of tropical formation over the southwestern Gulf of Mexico through the next seven days. As this potential tropical system, combined with steadily-deepening tropical moisture (with precipitable water values ranging between 2 and 2.5 inches), moves towards the western coast of the Gulf of Mexico, isolated/scattered showers and thunderstorms today and tonight will become scattered to numerous on Tuesday across the BRO CWFA. Temperature-wise, above normal values are forecast for today and tonight, with daytime highs on Tuesday cooled to more near normal levels due to increased cloudiness and rain chances. Heat indices do not suggest a HEAT ADVISORY during the short term forecast period, so will cover the indices with a SPECIAL WEATHER STATEMENT today and tomorrow. Finally, slightly more adverse marine conditions, courtesy of an increase in winds and building of seas, will lead to an elevated risk of rip currents at the local beaches today through Tuesday. && .LONG TERM... (Tuesday night through Sunday) Issued at 304 AM CDT Mon Jun 17 2024 Key Messages: * Tropical Cyclone Development in the SW Gulf remains at 70 percent * Increasing Rain Chances with Periods of Heavy Rainfall around Mid through Late Week. * Substantial Beneficial Rainfall Likely with Areas of Flooding Possible Confidence remains high with increasing atmospheric moisture and the chances of rain increasing leading to periods of heavy rainfall and potential flooding concerns in the long term forecast period. The potential development of a tropical cyclone in the SW Gulf of Mexico has increased to 60 percent within the next 48 hours and 70 percent within the next 7 days, though the system will not be around that long. Currently the system is located over the Central America and Southern Mexico, but is expected to move into the Bay of Campeche either today or tomorrow. Current model guidance still shows the center of this system moving into Central Mexico late Wednesday into Thursday. The model guidance does still show that there is another spin up that forms towards the end of the long term forecast period as well, however confidence is not high on the second system at this point. Moving into the main event of the long term forecast period, the long awaited rainfall that is highly anticpated for Deep South Texas and the Rio Grande Valley. The moisture content of the atmosphere over the Western Gulf of Mexico and Deep South Texas is very likely to increase drastically as deep tropical moisture is transported north and west between the ridges along the Pacific and Atlantic coast. By the start of the long term forecast period the PWATS over the region are around 1.9 inches based on the GFS and the NAM, however the ECMWF has PWATS at 2.1 inches. PWATS continue to rise through the day on Wednesday eventually reaching its peak on Wednesday night at a value of 2.9 inches. The current total QPF is in the range of about 4 to 7 inches. While the soils are very dry and could take up quite a lot of rainfall, there is still the concern that some flooding could take place if heavy rain fall is persistent enough. WPC currently has a marginal to slight risk for Excessive Rainfall Tuesday through Thursday for parts or all of Deep South Texas and the Rio Grande Valley. Expect many hazards to be in effect for the beaches during the long term forecast period as well. An enhanced pressure gradient is going to strengthen the southeasterly flow that will in turn build even greater swell. The result of this will be an increase in Rip Current risk, coastal flooding, high surf, and possible gale force gusts. Lastly, the temperatures for the long term forecast period. With the expected cloud coverage from the rain, high temperatures are not expected to be too hot and actually close to normal. As such the high temperatures are expected to be in the range of upper 80s to low 90s. While the low temperatures are expected to be mostly in the 70s, with a few places getting into the 80s. && .AVIATION... (12Z TAFS) Issued at 618 AM CDT Mon Jun 17 2024 No significant changes to the previous suite of TAFs. A TEMPO remains in effect for BRO and HRL for this morning`s potential for convection. Otherwise, VFR will prevail at all of the aerodromes through the next 24 hours, with light winds at night becoming breezy during the daytime. Partly to mostly cloudy skies will also occur. && .MARINE... Issued at 304 AM CDT Mon Jun 17 2024 Today through Tuesday...This portion of the total marine forecast is highly dependent on the area of disturbed weather over Central America, the Yucatan Peninsula, the waters of the northwest Caribbean Sea and southern Gulf of Mexico, and the possible future development and movement of a tropical system within it. Overall, Small Craft Should Exercise Caution (SCEC) and Small Craft Advisory conditions (SCA) are anticipated along the Lower Texas Coast through the period, with SCEC likely needed today, and SCA needed tonight through Tuesday. Tuesday night through Sunday...Marine conditions are expected to be Hazardous Tuesday night and remain that way through the work week, with Saturday starting to see some improving conditions. An enhanced pressure gradient will generate moderate southeast winds and seas. Small Craft Advisory conditions are expected to be present Tuesday night through early Saturday for the Gulf waters. While hazardous conditions are expected to come to an end a little sooner for the Laguna Madre. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 95 80 92 78 / 50 50 80 80 HARLINGEN 96 76 93 75 / 40 30 80 80 MCALLEN 98 79 95 78 / 20 20 70 60 RIO GRANDE CITY 99 78 96 77 / 10 10 50 50 SOUTH PADRE ISLAND 88 83 87 80 / 60 60 80 90 BAYVIEW/PORT ISABEL 92 79 90 77 / 50 50 80 80 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...High Rip Current Risk from this evening through Tuesday evening for TXZ451-454-455. GM...None. && $$