204 FXUS64 KBRO 010558 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1258 AM CDT Tue Nov 1 2022 ...New AVIATION... .SHORT TERM... (Tonight through Tuesday night) Issued at 225 PM CDT Mon Oct 31 2022 Latest GOES-16 WV/IR imagery shows a mid/upper-level trough centered over northwestern Mexico. Surface high pressure has already begun to shift northeastward over the northern Gulf coast, evident by the east-southeast winds currently blowing at the surface. In summary, precipitation chances increase through the afternoon and evening and will peak after midnight tonight. There is a treat of isolated strong to severe thunderstorms and very heavy rainfall after midnight, as well. Keep a rain coat and umbrella handy if planning to do any outdoor Halloween activities this evening. The main story in the short-term period continues to be the potential for locally heavy rainfall and isolated strong/severe thunderstorms overnight tonight. A few factors will contribute to these threats. First, strong upper-level divergence will occur over Deep South Texas as a 80+kt southwest-to-northeast jet moves over southern Texas this evening and overnight tonight. Secondly, moderate to strong vorticity advection will occur ahead of a 500mb trough that will be moving over western Texas late this afternoon and into this evening. MLCAPE values are forecast to increase between 800-1300 J/kg after midnight tonight, with highest values occurring along the coast and just offshore. Bulk shear (0-6km) will be maintained around 40-60kts through the overnight hours and into Tuesday morning. Forecast hodographs from the 12z NAM show impressive curvature in the 0-1km range, with 0-1km SRH values around 100 m2/s2. The combination of these values indicate the possibility of an isolated strong to severe thunderstorm or two developing overnight, best chances and timing between midnight and 9 AM Tuesday morning. The main hazards with any organized thunderstorm that develops will be damaging wind gusts of 60+ mph and maybe some small hail (<1"). However, there is a very small tornado threat that will peak between midnight and sunrise Tuesday. The Storm Prediction Center has painted a Marginal Risk of severe thunderstorms for all of the RGV tonight through 12z/7 AM Tuesday morning. On top of the severe thunderstorm potential tonight, there is a threat for very heavy rainfall that may lead to minor flooding and possibly flash flooding in a few isolated locations. PWATs are forecast to rise between 1.7-2.0 inches beginning early this evening, which is well above the 90th percentile for this time of the year. And like the severe weather threat, the heaviest rainfall is expected to occur after midnight tonight and through mid-morning as the 500mb trough shifts eastward and flattens out thereafter. Rain chances gradually decrease through the afternoon and through Tuesday night, mostly confined to the coastal counties and offshore. Overall, forecast rainfall amounts look to range between 1-3" across the CWA tonight through Tuesday night, with isolated amounts of 5"+ possible. Current 3hr FFG values show between 2-4" across the RGV and generally 4"+ across the Ranchlands. Therefore, scattered/widespread flash flooding is not likely to occur. For temperatures, another mild and rainy night is in store tonight with temps generally in the mid-upper 60s/near 70 degrees. Cloud cover and rain will keep temperatures relatively cool on the first day of November, with highs generally in the mid-upper 70s and lower 80s across the lower RGV. Similar low temperatures will occur Tuesday night as tonight under mostly cloudy skies. && .LONG TERM... (Wednesday through next Monday) Issued at 225 PM CDT Mon Oct 31 2022 Warmer than normal temperatures are expected for the second half of the week with widespread middle to upper 80s forecast each afternoon. Rain chances increase ahead of a cold front currently forecast to swing through sometime Saturday. Temperatures cool about 10 degrees behind the front over the weekend before moderating early next week. An H5 ridge will be building over the region to start the long term, which is why temperatures are forecast to be above normal the second half of the week. Meanwhile, a longwave trough diving through the Pacific Coast will begin ejecting eastward Friday into Saturday. As it does so, it will help spawn an area of low pressure across the panhandles of OK/TX Friday afternoon; this tightens the pressure gradient enough to lead to a breezy to windy day on Friday. As the low trudges eastward Friday and Saturday, it will drag a cold front through Texas. That cold front is forecast to swing through our County Warning Area (CWA) sometime Saturday morning. Deterministic models vary slightly on the timing with the GFS bringing it through around sunrise Saturday morning while the EURO holds it off until mid to late morning. Either way, rain chances are forecast to increase to around 30 percent ahead of and along the front before clearing out Saturday afternoon. High pressure builds in behind the cold front Saturday evening and beyond, which will help cool temperatures closer to normal (upper 70s/low 80s) Sunday on the heels of a light to moderate northeast to easterly winds. Winds turn southeasterly Sunday night into Monday and causes temperatures to jump back above normal early next week. && .AVIATION... (06Z TAFS) Issued at 1247 AM CDT Tue Nov 1 2022 Mostly MVFR conditions tonight with some IFR conditions possible in heavier showers and thunderstorms. Rain continues to throughout the area. Bands of showers and thunderstorms continue to flare up to our south as a warm front moving northward and seems that will be the trend for the overnight and early morning hours. Included showers and thunderstorms throughout most of the TAF. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 82 70 86 71 / 80 40 20 10 HARLINGEN 82 67 85 69 / 80 40 20 0 MCALLEN 81 68 84 69 / 60 30 10 0 RIO GRANDE CITY 78 66 83 68 / 60 20 10 0 SOUTH PADRE ISLAND 79 74 80 76 / 80 40 20 0 BAYVIEW/PORT ISABEL 81 69 83 71 / 90 50 20 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...54-BHM LONG TERM....69-Farris AVIATION...64-Katz/63-KC