027 FXUS64 KLIX 212305 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 605 PM CDT Sat Aug 21 2021 .AVIATION (00z Taf cycle)... VFR ceilings and light winds will prevail through the period. && .PREV DISCUSSION... /issued 358 PM CDT Sat Aug 21 2021/ SHORT TERM... 591DM ridge centered along the TX/LA border continues to be the biggest influence on the local weather. Its proximity to the CWA means low POPs was pretty much a given. Some stray storms have developed but they're quite small in areal size. In terms of the local heat products in effect, it appears that bit more dry air mixed down today than expected. This kept heat indices from reaching as high as forecasted. Thus, based on the trend so for today, decided to cancel the heat advisory and excessive heat warning in effect. The eastern side of the nearby ridge looks to erode slightly tomorrow. This should allow column moisture in increase enough to keep as much drier air from mixing down. At the same time, temps should still be quite warm, in the mid 90s with the ridge still as close as it is. Based on that, and has and hasn't been observed over the last 2 days, decided to just go with a heat advisory CWA-wide and no excessive heat warning. Thinking it'll be a marginal event with only some ASOS locations even touching 108 heat index. However, there will likely be enough of the CWA between those isolated points of measurement that actually do reach/exceed heat advisory criteria. Another aspect that'll start to change tomorrow due some erosion of the ridge is a few more updrafts actually developing into storms and not being capped. Saw no reason to change from the 20-30% NBM guidance. Will note that gusty winds mostly sub severe by strong will be possible with the most robust thunderstorms. LONG TERM... The remainder of the forecast will be a continuation of the the trend started on Sunday. The ridging aloft will be a little weaker each day. This should both lower temps and heat indices somewhat as well allow for higher rainfall coverage. Will be looking at upwards of 70% coverage by Tuesday afternoon and possibly lingering overnight showers by Wednesday. Even greater enhancement of the rainfall coverage is possible Wednesday through Saturday. This is due to an easterly wave tracking across the northern Gulf of Mexico from the western Atlantic. Although forecast PW's aren't alarmingly high, will need to keep an eye on how deep the tropical moisture is as it could potentially cause locally heavy rainfall. MEFFER AVIATION... Strong high pressure aloft has stunted almost all convection today. Thus, will not be carrying any VCTS or tempo groups for storms for the remainder of the TAF period. Light winds and VFR conditions will prevail. MEFFER MARINE... Surface high pressure will remain centered along the northern Gulf of Mexico but south of the local coastal waters through early next week. This will generally result in light/variable winds south of the mouth of the MS river and 8-12kts north of that latitude. There may be times when all the coastal waters observe light/variable winds as the ridge moves closer to the local area. Later half of the week looks to return more typical summertime persistent southeast flow as Bermuda ridge tries to build in. Models do show an easterly wave coming across the northern Gulf, which could alter the forecast some. MEFFER && .PRELIMINARY POINT TEMPS/POPS... MCB 73 94 74 96 / 10 30 20 30 BTR 74 94 75 96 / 10 30 20 40 ASD 76 96 77 96 / 10 30 30 50 MSY 82 97 81 96 / 10 30 20 50 GPT 77 95 77 95 / 10 30 30 50 PQL 76 95 76 94 / 10 40 40 50 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Heat Advisory from 9 AM to 7 PM CDT Sunday for LAZ034>037-039- 046>050-056>061-063>072-075>078. GM...None. MS...Heat Advisory from 9 AM to 7 PM CDT Sunday for MSZ068>071-077- 080>082. GM...None. && $$