FXUS64 KBRO 040519 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1119 PM CST Tue Dec 3 2024 ...New AVIATION... .UPDATE... Issued at 654 PM CST Tue Dec 3 2024 Interesting evening underway, as weak surface low pressure (inverted trough) was hugging the coast with a sharp wind shift between Bayview/South Padre and Brownsville. That same wind shift showed a sharp difference in temperatures, from the low to mid 70s on the coast where east winds continued, to the low to mid 60s in the Brownsville/Harlingen area...and around 60 in the mid Valley and upper 50s across the Brush Country. Bands of overrunning rain continued to roll across eastern Cameron County (especially), where daily totals were nearing 2 inches (1.8" unofficially) at Brownsville/South Padre Int'l Airport. The trough has also cranked up seas and swells above originally forecast, and web cams showed both rough/high/confused surf but also run-up toward the dune line just before sunset. Based on local guidance for the incoming swell as well as adjusted model forecast tide levels, have hoisted a Coastal Flood Advisory to continue through pre-dawn Wednesday. Tides may begin to run out a little sooner...but elected to add a buffer of around 6 hours after high tide (859 PM) based on the expected incoming easterly swell which may keep a prolonged buffer of water to or just into the dunes. Based on the surf and swells, hoisted a high surf advisory for the overnight. While unlikely that many will be venturing into the dangerous surf, the water temperatures remain above average (75 degrees) so decided to be prudent and add to the mix of coastal hazards. Expect a gradual recision of run up and high surf on Wednesday, so these hazards will likely expire...but rip currents will remain through at least sunset. && .SHORT TERM... (Tonight through Wednesday night) Issued at 215 PM CST Tue Dec 3 2024 The latest radar and satellite imagery depicts overcast skies and isolated to scattered showers across Deep South Texas and the Gulf waters this afternoon. The highest coverage of showers remains mainly along the immediate coast and Gulf waters, which coincides with the highest precipitable water values and proximity to a weak coastal low and associated frontal features. Surface observations and the latest RAP analysis indicate the center of the coastal low to be near or just south of the mouth of the Rio Grande River as of this writing. Unsettled weather will continue into tonight as the aforementioned surface features translate north along the Lower Texas coast, with the highest precipitation chances (40-70%) residing mainly along and east of the I-69 corridor through midnight. Pockets of locally heavy rainfall cannot be ruled out as moisture content remains high, but the axis of rainfall should shift further north of the Lower Rio Grande Valley over through the evening and tonight. After midnight, we should begin to see activity begin to taper off from south to north along the immediate coast as the coastal low translates north. Precipitation chances are somewhat lower (30-40%) west of I-69 tonight, but light to moderate showers cannot be ruled out. Otherwise, expect overcast skies and lows falling into the 50s region wide, with the exception along the immediate coast with lows in the low 60s. Most precipitation chances on Wednesday and Wednesday night will be confined over the Gulf waters and Lower Texas beaches, where the slightly higher moisture content will reside. For the rest of Deep South Texas, the combination of cloudy skies and generally light winds will promote a pleasant day with highs mostly in the low to mid 70s, slightly lower than seasonal normals for early December. Winds will gradually shift to the south through Wednesday afternoon, which will result in slightly warmer low temperatures Wednesday night ranging from the upper 50s across the Rio Grande Plains to upper 60s and low 70s across the Lower Rio Grande Valley and immediate coast. Along the Lower Texas beaches, a high risk of rip currents will continue through Wendesday evening as winds and seas remain elevated in response to the northward-moving coastal low. && .LONG TERM... (Thursday through next Tuesday) Issued at 215 PM CST Tue Dec 3 2024 Upper level troughing over the western continental U.S. will bring southwesterly flow aloft and coax a coastal low to meander north early in the long term. As the coastal low pushes northward Thursday, it will bring chances of rain, with highest chances expected Thursday evening over the Gulf Waters before backing off over the weekend. PoPs drop to less than 20% for the region, bar along the coast, for the weekend and early next week. The fate of next week lies in the timing and strength of a cold front associated with the CONUS trough, which at this time are uncertain, but continue to be monitored. European vs. North American guidance both agree this trough will evolve into a cut- off low over AZ/western Sonora by the weekend, however timing and trajectory vary between each. Temperatures start off near-seasonal in the beginning of the period, with northern ranchlands highs near 70 and lows in the 50s, and lower valley/coastal highs in the 70s - nearing 80 - and lows in the 60s. Temps may creep up early next week as 850hpa winds advect the shallow moisture remaining in the lower atmosphere. A tightening pressure gradient ahead of the coastal low late Thursday/early Friday will increase winds and return elevated seas, leading to a likely chance of increased rip current risk for the local beaches Friday. && .AVIATION... (06Z TAFS) Issued at 1120 PM CST Tue Dec 3 2024 06Z forecast will be a continuation of the inherited forecast from 00Z (6 PM), which carries a persistent IFR/LIFR ceiling through the night and well into Wednesday morning before some erosion/lifting toward noon or a bit later. Guidance packages are still in somewhat different camps, with the GFS a bit more positive on lifting ceilings, including at Harlingen and Brownsville. For now, have leaned more pessimistic with ceilings lifting to low MVFR during the afternoon in the lower Valley and low VFR at McAllen. By sunset, winds lay down completely and dewpoints may sneak up, allowing ceilings to fall once again and lower visibility (mist) to enter the stage. Have added MVFR (5SM BR) to account. && .MARINE... Issued at 654 PM CST Tue Dec 3 2024 Aforementioned rise in seas/swell to 10 feet and 9 second period at buoy 42020 enough to both raise the values in the Coastal Waters Forecast and the Small Craft Advisory hazard. Extended the Advisory through noon Wednesday (seas) and may need to extend longer for at least the 20-60 nm leg but perhaps all of the waters, depending on swell direction by afternoon. A continued east to east-southeast direction would push at least 7 foot waves into the 10-20 nm portion of the nearshore, enough to extend all Gulf waters through 6 PM. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 61 75 67 80 / 60 20 10 40 HARLINGEN 57 73 63 80 / 50 10 10 40 MCALLEN 57 73 64 80 / 30 0 10 30 RIO GRANDE CITY 52 72 60 75 / 30 0 0 30 SOUTH PADRE ISLAND 67 74 71 77 / 70 30 20 50 BAYVIEW/PORT ISABEL 60 74 65 78 / 60 20 20 50 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Coastal Flood Advisory until 5 AM CST Wednesday for TXZ451-454- 455. High Rip Current Risk through Wednesday afternoon for TXZ451-454- 455. High Surf Advisory until 7 AM CST Wednesday for TXZ451-454-455. GM...Small Craft Advisory until noon CST Wednesday for GMZ150-155-170- 175. && $$ AVIATION Update...52-Goldsmith