982 FXUS64 KLIX 111342 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 842 AM CDT Thu Oct 11 2018 .SOUNDING DISCUSSION... This morning's balloon launch was successful with no problems encountered. Very significant differences in this morning's sounding profile when compared to the previous 24 hours thanks to departing Hurricane Michael and a passing front. Much drier air has pushed in from the NW at the surface to the mid-levels, with several embedded subsidence inversions (noted by slight compressional warming between 700 and 500mb) as well as a radiation inversion at the surface. PW's this morning were calculated at 0.61 inches, a drastic change from 2.11 inches yesterday morning which will make it feel much more like fall today. The vertical wind profile indicates prominent backing in the wind direction from the sfc to 500mb, indicative of a dominating cold air advection pattern. Modifying the sounding for forecasted highs, and comparing it to the latest 13KM RAP guidance this afternoon illustrates a beautiful day ahead. Not much, if any clouds this afternoon with brilliant blue skies and no rain chances. Welcome to fall! KLG && .PREV DISCUSSION... /issued 411 AM CDT Thu Oct 11 2018/ Fall? Is that REALLY you? It certainly looks that way, thanks to some help from Hurricane Michael. Surface observations over the last several hours show steady northwest winds ushering in a much drier air mass. Dewpoints have dropped into the mid to lower 60s for most of the CWA. Temperatures are following suit, dropping slowly by steadily and should be dropping into the lower to upper 60s. Strong surface high pressure building in from the north will continue to usher in cooler air. Highs may not even reach 80 in the northwestern half of the CWA. These types of cool temps with sunny skies haven't been felt in the region since around the last weekend in April. A subjective analysis shows this recent cold front may be the latest ever first cold front of the fall season. Continuing on into the weekend, little change is expected in the overall weather pattern. The surface ridge will gradually shift from northwest to northeast of the forecast area by Saturday afternoon. This will keep temperatures at to slightly below normal for this time of year. Moisture will begin to return Sunday as the surface high slides further east and an upper ridge builds in from the western Atlantic across the Gulf of Mexico. In response, dewpoints and temps will be back on the rise with highs coming back up into the mid to upper 80s. Outside of isolated showers, shouldn't be much if any convection just yet on Sunday. Its not until Monday and Tuesday that appreciable rain chances return. An upper trough diving across the southern Rockies Monday will swing across Texas Tuesday and continue east to the East Coast Wednesday. This will bring another cold front to and through the region. Expecting rain chances to come up and may be too low ATTM for POPS during that time frame. Much cooler temps to follow behind the boundary. MEFFER .AVIATION... VFR through the forecast period. Only issue is the likelihood of wind gusts above 20 knots at KNEW and KMSY overnight as cold air advection moves over Lake Pontchartrain where water temperatures remain in the 80s. 35 .MARINE... Wind speeds and seas trending downward. Not seeing any sites reporting much more than 20 knots or 5 foot seas at this time and will lower SCA to Exercise Caution headlines through 00z Friday. May be another slight surge in winds over the eastern waters tonight that could require extending headlines there, but otherwise anticipate onshore flow returning over the weekend, but only at 10 to 15 knots. Next period of concern will be at midweek next week with the next surge of cold air behind a front. Regarding Coastal Flood Advisory, still seeing one site around Lake Maurepas with water still above flood stage, but it is steadily falling, and water is no longer getting pushed into that area. At it's current rate of fall, should fall below flood stage during the morning, so the current plan is to allow the Advisory to expire on schedule at 6 am. 35 .DECISION SUPPORT... DSS code: Green. Deployed: None. Activation: None. Activities: None. Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event; Marginal risk severe or excessive rain. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support for Slight risk severe or excessive rain. Orange = High Impacts; Enhanced risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for moderate to high risk of severe and/or excessive rain; direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 78 51 79 57 / 0 0 0 0 BTR 79 52 80 58 / 0 0 0 0 ASD 82 52 80 60 / 0 0 0 0 MSY 82 60 79 64 / 0 0 0 0 GPT 83 58 79 62 / 0 0 0 0 PQL 85 54 80 58 / 0 0 0 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$