070 FXUS64 KBRO 190602 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 102 AM CDT Tue Oct 19 2021 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...Light to variable southeasterly winds will continue overnight. Patchy fog is possible early Tuesday morning in the Northern Ranchlands area but in regards to near the aerodromes, confidence is low for it to form at this time. VFR conditions are expected to prevail through the period. && .PREV DISCUSSION... /issued 621 PM CDT Mon Oct 18 2021/ DISCUSSION...Updated for latest aviation discussion below. AVIATION...Partly cloudy skies will continue to lead to VFR conditions across all aerodromes through this evening. Overnight and into Monday VFR will continue to prevail for BRO and MFE, but some low level clouds could lower visibilities at HRL with MVFR conditions possible around daybreak before VFR conditions return by mid morning. PREV DISCUSSION... /issued 300 PM CDT Mon Oct 18 2021/ SHORT TERM (Now through Tuesday Night): Little change to the going forecast, which is dominated by fair weather with a gradual return to more average mid-late October temperatures and humidity by Tuesday/Tuesday night. These conditions courtesy of modifying (warming) air mass on the backside of surface high pressure over the southeast U.S. as well as the area being on the backside of flat 500 mb ridge that will center over the south-central Gulf Tuesday and Tuesday night. In terms of sensible weather...expect to see more mid and high clouds, along with scattered fair weather cumulus, from early Tuesday through Tuesday night courtesy of broad west-southwest flow aloft pulling in some deeper moisture from the eastern subtropical Pacific. Otherwise, given the slow rise in dewpoints, lengthening night, and long period of light winds, have blended in some patchy light fog to cover the King Ranch region of Brooks/Kenedy south through the rural areas of the mid/lower Valley late tonight. Not as confident in fog early Wednesday...but elected to add given similar conditions even though temperatures will be a touch warmer...upper 60s in these areas by daybreak Wednesday. Temperatures will be right around seasonal normals (upper 80s by afternoon, 65-70 by daybreak) Tuesday/Tuesday night after one more slightly cooler than average night tonight. LONG TERM (Wednesday through Monday): Upper and midlevel flow will remain largely zonal to begin the long term. The lack of any appreciable troughs/waves in the pattern combined with low RH at midlevels allows for fair and warm weather to continue, with temperatures rising to near or even slightly above seasonal normals. A few very weak and diffuse midlevel shortwaves may help to induce some weak disturbances, the lift from which will help increase atmospheric moisture on Thursday. The increasing moisture and added weak forcing may allow for some widely scattered showers or thunderstorms to develop Thursday through Saturday. The best chances for any precipitation chances look to be across far eastern portions of the CWA and especially over the Gulf Waters. The synoptic pattern then becomes a bit more interesting and amplified for the latter portion of this weekend. A strong upper trough over the Pacific Northwest will begin to dig in over the western US while also helping to amplify a ridge over the Central/Midwestern US. This results in a general pattern of weak troughiness setting up over western Texas. At the same time, medium to long range guidance is hinting at a tropical cyclone developing off the southwestern Mexican coast later this coming weekend. The strong upper trough will likely help to pull this system inland, which in turn may drag a plume of moisture northward across central Mexico and into the south-central US. The GFS remains the more bullish model in terms of rainfall for next week, with the ECMWF keeping the CWA mostly dry. While it is far too early to comment on specific timing and magnitude of rainfall given the current uncertainty stemming from model discrepancies, the pattern looks at least somewhat favorable for some enhanced rainfall during the early portion of next week. MARINE (Now through Tuesday Night): Light winds and slight to moderate seas will dominate the period under the aforementioned high pressure ridge. Seas had dropped to 3 feet this afternoon and period had dipped to 6/7 seconds as well...and with steady-state 10 knot winds...perhaps 10-13 knots Tuesday evening...see a bit more drop into the 2-3 feet range this evening holding through early Wednesday. Laguna Madre winds should dip to 5 knots or less by midnight and continue through late morning Tuesday before the usual afternoon pickup...before dropping back later Tuesday night. Bottom line? Ideal boating and fishing conditions for those headed out. Wednesday through Saturday: Broad high pressure at the surface will remain nearly anchored over the southeastern US and western Atlantic. This will favor light to occasionally moderate winds at times and subsequently lower seas. Low pressure developing over the Central Plains on Saturday may help to strengthen the surface pressure gradient, with winds perhaps reaching SCEC levels by Saturday evening. The main concern for mariners in the meantime remains the slight chance for scattered showers and thunderstorms Thursday through Saturday as a series of weak midlevel waves and disturbances move over the region. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 86 70 87 72 / 0 0 10 0 BROWNSVILLE 86 72 90 72 / 0 0 10 10 HARLINGEN 88 69 89 69 / 0 0 0 0 MCALLEN 90 71 92 71 / 0 0 0 0 RIO GRANDE CITY 91 68 93 69 / 0 0 0 0 SOUTH PADRE ISLAND 83 77 83 78 / 0 0 10 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: https://weather.gov/rgv 65-Soria/Aviation