FXUS64 KBRO 111731 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 1131 AM CST Mon Dec 11 2023 ...New AVIATION... .SHORT TERM... (Today through Tuesday) Issued at 318 AM CST Mon Dec 11 2023 The short term period will feature slightly below normal temperatures, increased cloudiness, and rain-free conditions. Calm winds prevail early this morning across all of Deep South Texas as surface high pressure settles along the Texas coast. Winds should begin to increase in speed (below 10 mph) and shift to the southeast by mid to late morning as the surface high translates east. Meanwhile, an mid/upper level trough will over Central Mexico will translate toward South Texas through the day, placing the region beneath southwesterly flow. As Pacific moisture is transported northeastward, we should begin to see an uptick in cloud cover by mid to late afternoon. The combination of return flow and insolation should result in slightly warmer temperatures (although still slightly below normal for mid December), with highs ranging from the mid 60s across the Northern Ranchlands to around 70 degrees across the Rio Grande Valley. High res guidance continues to indicate persistent low level southeasterly flow should result in the development of stratus clouds across portions of the region tonight. Overcast skies should result in warmer low temperatures tonight as cloud cover limits radiational cooling processes, with low temperatures ranging from the upper 40s to upper 50s. The mid/upper level trough will continue to translate toward the Lower Texas coast into Tuesday, which should result in the return of sunshine at least through early Tuesday afternoon before mostly cloudy skies return. Highs will top out in the 70s region wide. && .LONG TERM... (Tuesday night through Sunday) Issued at 318 AM CST Mon Dec 11 2023 A coastal trough with some mid-level support and ample moisture are expected to set up along the lower Texas coast Tuesday evening. PWAT values should increase to around 1.5 inches by Tuesday night and remain high through late week. The combination of these features will lead cloudy skies and increasing rain chances through the first half of the weekend. A 500 mb over the Great Basin region Tuesday night will move into southern Arizona and New Mexico Wednesday night into Thursday. The best rain chances will arrive Thursday into Friday as the mid-level low swings over north Texas and slowly moves eastward through the rest of the long term period. Rain chances quickly diminish on Saturday with the passage of the mid to upper level trough axis and dry northwest flow aloft prevails. Near to slightly above normal temperatures are expected Tuesday night through Thursday night due to the increase in cloud cover and rain chances. Overnight lows will fall into the 60s each night and highs Wednesday and Thursday are expected to reach the low to mid 70s. Surface high pressure will build into the region allowing for a resurgence of cold air into the region resulting in falling temperatures late week and into the weekend. Highs on Friday are expected to range from the mid 60s to the mid 70 with lows Friday night mainly in the upper 40s to the lower 50s. Cool to mild days and chilly nights are expected for the weekend into early next week. Finally, surface high pressure across along the northern Gulf Coast will support a long fetch of easterly winds which will generate long period swell across the northern Gulf of Mexico. This may lead to minor coastal flooding and dangerous beach conditions along the Lower Texas Coast, especially Wednesday into Friday. && .AVIATION... (18Z TAFS) Issued at 1127 AM CST Mon Dec 11 2023 High overcast VFR cloud deck prevail today and tonight, although the high ceiling are expected to lower towards sunrise. As moisture increases overnight another cloud deck between 4-5,000 feet is likely to develop around or after sunrise and potentially lower during the latter half of Tuesday. Light east to southeast winds prevail through the 18Z TAF package. && .MARINE... Issued at 318 AM CST Mon Dec 11 2023 Today through Tuesday...Favorable marine conditions are expected through the period. Winds will shift to the east and southeast on Monday as the surface ridge translates east, with seas around 2-3 feet. Tuesday Night through Sunday...Adverse conditions are expected to develop by Tuesday night as a coastal trough develops and building easterly swell. Elevated seas and stronger winds will lead to a long duration of Small Craft Advisories Tuesday night through the weekend. The presence of the coastal trough will support scattered to numerous showers and isolated thunderstorms Tuesday night through the first half of the weekend. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 69 58 74 65 / 0 0 0 10 HARLINGEN 70 54 74 62 / 0 0 0 10 MCALLEN 69 54 72 62 / 0 0 0 10 RIO GRANDE CITY 67 51 71 61 / 0 0 0 10 SOUTH PADRE ISLAND 68 62 71 67 / 0 0 0 10 BAYVIEW/PORT ISABEL 68 57 73 63 / 0 0 0 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...22-Garcia LONG TERM....63-KC AVIATION...59-GB