Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
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977 FXUS64 KLIX 142053 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 353 PM CDT Fri Jun 14 2024 ...New SHORT TERM, LONG TERM, MARINE... .KEY MESSAGES... 1. A surge of tropical moisture will enhance rain chances starting Sunday and continuing into next week. Locally heavy rainfall that could lead to flash flooding especially in poor drainage areas will be possible especially on Sunday and Monday. 2. Increasing onshore winds into next week will bring a large enough fetch to increase coastal flooding concerns. Latest forecasts indicate minor coastal flooding will be possible for east and south- facing shores by Tuesday into Wednesday. 3. Hazardous marine conditions, especially for small crafts, are expected as winds and seas increase starting Sunday. Sustained winds are expected to be approaching 25 to 30 knots with gusts as high as gale-force by midweek. && .SHORT TERM... (This evening through Saturday night) Issued at 305 PM CDT Fri Jun 14 2024 Short term will be relatively quiet as high pressure remains in control of the weather. Upper level ridging and subsidence will keep rain chances low through tomorrow night. The lack of cloud cover and convection will also allow temperatures to rise into the mid to upper 90s in the afternoon, with some areas possibly reaching 100 degrees. The "good" news is that even with the high afternoon temperatures, slightly drier air aloft will mix down during the afternoons, which will keep relative humidity a bit more bearable and should prevent heat index values from rising to advisory criteria. In general, heat index readings are currently forecast to peak in the 100 to 105 degree range for most places tomorrow. && .LONG TERM... (Sunday through Thursday night) Issued at 305 PM CDT Fri Jun 14 2024 The primary features being monitored in the long-term are to do with the interaction between deep, tropical moisture from the Caribbean and upper-troughing lingering over the Gulf of Mexico. The first feature we`ll be watching is associated with the decaying frontal boundary over the Yucatan Channel which is quite convectively active today due to the upper trough imposing upper- diffluence across the area, venting the convection. With the easterly Caribbean trade winds piling up over this area of the northwest Caribbean Sea, this can sometimes be a setup where a tropical cyclone would try to form. But, fortunately for us, strong upper troughing is imposing hostile westerly wind shear across much of the Gulf of Mexico. As this inverted surface trough begins to be pushed to the northwest by the strengthening Bermuda high, it appears to stay intact and act similar to that of a tropical wave. The arrival of this surface trough on Sunday will locally enhance the pressure gradient and bolster PoPs through the afternoon. Guidance has trended up with how pronounced this surface trough is currently, so this has also trended PoPs up as well. Ample moisture with diffluence aloft from upper troughing will yield thunderstorms capable of high rain rates of 2 to 3 inches per hour and flash flooding as a result, especially in poor drainage areas. The risk for locally heavy rainfall and flash flooding will be its highest Sunday through Tuesday. Beyond heavy rainfall discussion, Sunday`s highs won`t be as hot as Friday and Saturday, but deep tropical moisture combined with morning to midday sunshine will allow heat indices to get back up into the 100s before the rain arrives. Thereafter, we cool off with high PoPs (>70%) associated with deep tropical moisture and southeasterly, onshore flow. The pressure gradient will be enhanced as a tropical disturbance develops in the Bay of Campeche with strong high pressure to our northeast still in place. This will generate sustained winds of 15 to 25 mph across the coastal areas with gusts as high as 30 mph. Persistent onshore flow will also result in a large enough fetch to cause minor coastal flooding across east and south-facing shores by Tuesday into Wednesday. Continue to monitor the forecast for further changes. While the tropics have started to wake up with a couple of disturbances noted in the NHC outlook, the general pattern will continue to favor westerly wind shear across the northern Gulf Coast through the next 7 days which is unfavorable for tropical cyclones. This is due to strong upper-level ridging centered over the Bay of Campeche in association with the Central American Gyre (CAG) with upper troughing still stuck over the northern Gulf Coast. The CAG will linger over Central America through the next 7-10 days, but there is no indication of any tropical cyclones bringing impacts to the northern Gulf Coast for at least the next 7 days. && .AVIATION... (18Z TAFS) Issued at 1236 PM CDT Fri Jun 14 2024 VFR conditions will prevail through the period with winds less than 10 knots as high pressure remains in control of the local area weather. && .MARINE... Issued at 305 PM CDT Fri Jun 14 2024 High will keep conditions generally benign through Saturday with light winds and seas 2 feet or less. As the high shifts eastward on Sunday in response to a broad low developing over the Bay of Campeche, the pressure gradient will tighten somewhat and cause winds to strengthen to 10 to 15 knots. Additionally, a surge of deeper moisture will result in higher rain chances by Sunday as well. Winds will strengthen further during the first part of the work week and Small Craft Advisories will likely be needed for most of the coastal waters beginning Monday night with some potential for gale force gusts as well. The strong east/southeast winds will persist through at least Wednesday, causing tides to rise above normal as well. At least minor coastal flooding impacts appear likely in some of the more vulnerable areas by the high tide cycle Tuesday. && .PRELIMINARY POINT TEMPS/POPS... MCB 70 96 71 95 / 0 10 0 30 BTR 75 100 76 94 / 0 10 0 50 ASD 74 97 75 92 / 0 10 0 50 MSY 79 96 79 91 / 0 10 0 60 GPT 76 96 77 91 / 0 10 10 50 PQL 72 98 74 91 / 0 10 10 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$ SHORT TERM...DM LONG TERM....TJS AVIATION...DM MARINE...DM