Area Forecast Discussion
Issued by NWS Brownsville, TX

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626 FXUS64 KBRO 212354 AAA AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 654 PM CDT Fri Jun 21 2024 ...New UPDATE, AVIATION... .UPDATE...
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Issued at 639 PM CDT Fri Jun 21 2024 Will allow the current Coastal Flood Advisory to expire at 7 PM as water levels continue to slowly fall along the Lower Texas Coast. However, current observations/webcameras suggest surf conditions continue to be hazardous. Therefore, will extend the current High Surf Advisory through 7 AM Saturday.
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&& .SHORT TERM...
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(Tonight through Saturday night) Issued at 216 PM CDT Fri Jun 21 2024 Key Messages: - There is a 50% chance of tropical development near the Bay of Campeche over the next 48 hours. - Minor coastal flooding due to elevated seas and tides, as well as a high risk of rip currents, will continue through Saturday night. Deep South Texas will remain in an unsettled weather pattern through the short term period as an area of low pressure translates westward from the Bay of Campeche towards Southeastern Mexico. Meanwhile, the mid/upper level ridge centered over the Northeast US earlier this week will continue to shift toward the Southern Plains late this afternoon and evening. While the broad area of low pressure is in the general location of where Tropical Storm Alberto developed earlier this week, a more westward track is likely as the ridge builds over the Southern Plains. This scenario would keep our highest precipitation chances mainly over the Rio Grande Valley and Gulf waters, as the subsidence associated with the ridge will not be quite as strong. The latest probabilities from the National Hurricane Center indicate there is a 50% chance of tropical cyclone development over the next 48 hours. Should any further development occur tonight, it is possible a tropical depression could develop over the weekend. Despite any tropical development, the main impacts for Deep South Texas would be locally heavy rainfall, increasing seas, and a high risk of rip currents along Lower Texas beaches. Given the beneficial rainfall most of Deep South Texas received earlier this week, any locally heavy rain may result in minor flooding issues. Isolated instances of flash flooding cannot be ruled out, especially in low- lying areas or flood-prone areas. Overall, rainfall amounts will range from around 0.5" across the Northern Ranchlands to around 1.5" across the Rio Grande Valley (locally higher amounts close to 2") through Saturday night. For the Lower Texas beaches, a high risk of rip currents will continue through at least Saturday night. Wave heights are expected to slowly decrease tonight, but may increase slightly once again on Saturday with the westward movement of the area of low pressure. Minor coastal flooding issues may develop once again and a Coastal Flood Advisory may be needed. Otherwise, the combination of increased cloud cover and rain chances will result in slightly below normal temperatures for mid June, ranging from the low 90s across the Northern Ranchlands to mid to upper 80s across the Rio Grande Valley. Low temperatures will be mostly in the 70s region wide, with
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&& .LONG TERM... (Sunday through next Friday) Issued at 216 PM CDT Fri Jun 21 2024 Key Messages: _ Tropical Low (possible cyclone)approaching Tamaulipas Coast Sunday - Heavy Rain Potential Sunday - Coastal/Marine Impacts Possible Sunday/Monday - Back to typical June Weather Tuesday-Friday The Sunday and Monday forecast is highly dependent on the future track and strengthening of the tropical disturbance expected to move into the Bay of Campeche/Southern Gulf waters tonight or early Saturday. NHC has a 50 and 60 percent chance of tropical cyclone development in the next 2 to 7 days respectively. For the latter portion of the long term mid-level ridging to dominate and drive the forecast trends. Sunday trends on the wetter side as moisture surges over the RGV. All deterministic models show significant POPs as the available deep tropical moisture converges along a low pressure trough and moves inland. Precipitable water values once again climb in the 2-2.5+ inch range which will provide the opportunity for heavy rainfall. At this time, average WPC QPF values for Sunday range from 0.5-1 inch (less over the northern Ranchlands). Can not rule out higher amounts up to 2 inches in isolated thunderstorms or training of heavier showers. With this said, only the counties of Cameron, Willacy, Hidalgo and Starr are within the day 3 Excessive Rainfall outlook issued by WPC. Not anticipating a Flood Watch, however nuisance street and low-lying flooding is possible especially with areas that received more than 3 inches earlier this week. Temperatures Sunday are likely to be below normal in mid 80s to lower 90s as clouds and rain keep insolation limited. Residual high moisture content and differential heating Monday should be sufficient for another round of scattered showers and a few thunderstorms. Rain chances may be a bit robust as the mid- level ridge becomes established over Texas and the Desert SW so there may be some adjustments to trend lower on the POPs in the next few days. Near normal temperatures are expected with lows in the 70s and highs in the 90s. Tuesday-Friday look to trend near seasonal conditions with the mid- level ridge strengthening over the Desert SW and a mid-level low pressure trough shown to move over the north-central Gulf of Mexico. This places Deep South Texas in a weak shear zone with modest low level moisture and increasing subsidence in the mid-levels. Forecast temperatures are likely to trend up while isolated sea breeze convection are possible mainly east of I-69C. Coastal impacts on Sunday due to the tropical entity moving toward the Southern Tamaulipas/northern Veracruz coast will also be highly dependent on future strengthening. In any case, worse case scenario would be coastal flood advisories especially at the high tide cycle and high risk of rip currents. At least a moderate risk of rip currents is likely for Monday and Tuesday. && .AVIATION...
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(00Z TAFS) Issued at 639 PM CDT Fri Jun 21 2024 The latest radar and satellite observations reveal mostly VFR conditions with isolated SHRA/TSRA across the region early this evening. Rain chances increase late tonight into Saturday as the broad area of pressure over the Bay of Campeche continues to move west northwestward toward Southeastern Mexico. Scattered showers and isolated thunderstorms will likely persist by mid morning Saturday through the afternoon/evening hours. Locally heavy rain may result in reduced visibility at the terminals. Otherwise, MVFR ceilings will return around 14-16Z.
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&& .MARINE... Issued at 216 PM CDT Fri Jun 21 2024 Tonight through Saturday night...Moderate northeast to east winds and elevated seas will prevail through the period and result in Small Craft Exercise Caution to Small Craft Advisory conditions over the Gulf of Mexico and Laguna Madre. Scattered to numerous showers and isolated thunderstorms will remain likely through the period the airmass remains unsettled. The NHC currently has a 50% chance of tropical development near the Bay of Campeche over the next 48 hours, which could result in higher winds and seas than currently forecast. Sunday through Friday...Latest models continue to show a weaker and less broad tropical low pressure area moving over the Southern Gulf waters. This translates into a smaller wind field with lower winds and lower seas. Conditions on Sunday look to in the exercise caution to low end small craft advisory level as the tropical entity approaches the Mexican coast about 300 miles south of the mouth of the Rio Grande. As high pressure builds over the northern Gulf the remainder of the week winds and seas will be trending lower with light to moderate winds and slight seas. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 78 88 78 90 / 80 80 90 90 HARLINGEN 75 88 76 90 / 60 80 80 90 MCALLEN 76 87 77 90 / 60 80 70 90 RIO GRANDE CITY 76 87 76 89 / 50 80 60 90 SOUTH PADRE ISLAND 81 85 81 86 / 80 80 90 90 BAYVIEW/PORT ISABEL 78 88 79 89 / 80 80 80 90 && .BRO WATCHES/WARNINGS/ADVISORIES...
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TX...Coastal Flood Advisory until 7 PM CDT this evening for TXZ351- 354-355-451-454-455. High Rip Current Risk through Sunday morning for TXZ451-454-455. High Surf Advisory until 7 AM CDT Saturday for TXZ451-454-455. GM...Small Craft Advisory until 7 PM CDT this evening for GMZ150-155- 170-175.
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&& $$ SHORT TERM...63-KC/22-Garcia LONG TERM....59-GB AVIATION...63-KC