699 FXUS64 KLCH 280354 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 954 PM CST Fri Dec 27 2019 .UPDATE... Vsby remains up this eve as cloud deck remains low with light southerly winds less than 10 mph. Radar has some light rain over the Louisiana coastal waters with dense fog in the coastal waters. This will linger through the overnight into the morning hours. Not looking at any abatement until maybe the noon hour as rains and storms begin to filter in from the northwest ahead of the next front on Sunday. Heaviest rains expected during the late morning hours on Sunday with drying during the late afternoon into the evening hours behind the front on Sunday. As for tonight look for areas of fog that will lower the vsby to 3 to 6 miles inland but vsby will be lower at the coast and beaches 1/4 to 1 mile. Dew points are in the mid 60s but will gradually drop through the overnight hours allowing for temps to fall into the lower 60s by sunrise. Currently zones are fine and no updates are planned. Next week...temperatures back to seasonal levels with skies clearing on Monday. && .PREV DISCUSSION... /issued 605 PM CST Fri Dec 27 2019/ DISCUSSION... For the 28/00Z Taf Issuance package. AVIATION... MVFR conditions in place or will be in place all areas tonight before transitioning to IFR conditions all areas by midnight. Overnight a soupy mix of low clouds and a stray shower is possible. VFR conditions will return around 18Z Saturday. Mostly the timing of the low clouds is currently the challenge...especially the IFR deck that is just off the coast but spreading inland soon. PREV DISCUSSION... /issued 334 PM CST Fri Dec 27 2019/ SYNOPSIS... Favorable conditions for dense sea fog for marine areas into Saturday morning. A cold front will move across the forecast area on Sunday with widespread shower activity. A few thunderstorms may be embedded in the showers and these storms may become rather strong and the Storm Prediction Center has outlined the area north of a Jasper to Marksville line in a Marginal Risk for severe storms late Saturday into early Sunday. After a cool dry period to end the year, another period of rather rainy weather looks to be in store to start the New Year. Rua DISCUSSION... As we enter the final weekend of this decade, a relatively warm and moist period is in store, that will bring about a marine fog hazard and the possibility of storms. A rather potent cut off low over Arizona is beginning to move off to the northeast. This will allow southerly flow to increase tonight into Saturday, helping to increase warm air advection and moisture for the region. The first concern is the possibility of dense sea fog. At this time, it looks like the more favorable conditions for the dense sea fog will stay over the near shore waters and right at the coast, as winds above the surface look to become strong enough to lift the fog into low ceiling stratus as it moves inland. Lift above the marine layer will also allow for occasional light drizzle or light rain showers through the night into Saturday morning. During the day on Saturday into Sunday, the focus will be more on the potential for shower and storm development as upper level low deepens as it moves into the Plains, with strong winds developing above the surface to provide really good shear numbers, with 0-3km bulk numbers between 30 and 40 knots, and 0-6km bulk numbers over 50 knots by afternoon. The southerly flow will also bring in highly anomalous moisture values, with Precipitable Water values increasing to around 1.5 inches, which is over the 90th percentile climo value of 1.35 inches. As the upper level trough and surface cold front approach the forecast area Saturday night, increasing lift will work with the ample moisture to produce widespread shower activity from west to east during the night. If shower activity can develop into full blown thunderstorms, and how strong they get, will depend on the low level instability. At this time, most unstable CAPE looks to be rather meek, with values mainly below 500 j/kg. Therefore, not expecting too much in the way of thunder activity. Still, the rather impressive wind profile leads to the possibility of a few strong to severe storms inland away from any marine layer influences, and thus the Storm Prediction Center has outlined the area along and north of roughly a Jasper to Marksville line in a Marginal Risk for severe storms. The main hazard would be straightline winds, however if any storm can really get going, then a quick spin up can not be ruled out. Once the cold front moves through during the day on Sunday, shower activity will be ending from west to east, with much cooler conditions, that will continue into the last couple of days of 2019. Next concern will be in the middle to later part of next week and the beginning of the new year. As high pressure moves off to the east, and another upper level system develops over the southwest US, a coastal trough feature is noted by Wednesday along the upper Texas coast. Disturbances will override this feature bringing increasing rain chances by late Wednesday. Activity will only increase on Thursday as a rather potent upper level disturbance will likely allow for a surface low to develop along the coastal trough and travel across the forecast area. Projected precipitable water values are well over 1.75 inches and near or exceeding max climo values. Therefore, will have to watch this situation closely for a period of heavy rainfall. Rua MARINE... Warm moist air with dew point readings right around or just above water temperatures, along with favorable winds, will allow for the development of sea fog again tonight into Saturday morning. Expect that the sea fog will have widespread visibilities below 1 nm, therefore, will have a marine dense sea fog advisory through Saturday 9 am local. An increase in wind speeds and an increase in lift, may allow for sea fog to become a bit more patchy in nature during Saturday. A cold front will move across on Sunday, with modest northwest winds developing behind it into Monday. The cooler and drier air should end any chance for sea fog for a few days. Rua && .PRELIMINARY POINT TEMPS/POPS... AEX 60 76 58 68 / 30 50 80 90 LCH 63 76 61 71 / 20 20 60 80 LFT 64 77 65 74 / 20 30 40 80 BPT 62 74 60 68 / 10 30 70 90 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...Dense Fog Advisory until 9 AM CST Saturday for GMZ430-432-435- 450-452-455. && $$ PUBLIC...19