831 FXUS64 KLIX 201312 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 812 AM CDT Fri Oct 20 2017 ...SOUNDING DISCUSSION... The sounding is still stable and overall dry this morning. There is a 10 F radiation inversion in the first 1000 ft and an elevated inversion above at 800 mb. Stronger easterly flow will result in more moisture return today and spot showers, mainly near the south Louisiana coast. Winds are at 20 kts already just above the surface. Krautmann && .PREV DISCUSSION... /issued 333 AM CDT Fri Oct 20 2017/ SYNOPSIS... Surface high currently centered over the Appalachian Mountains. Low pressure was centered over the Canadian Rockies with a cold front down the lee side of the Rockies. An inverted surface trough was located over the western Gulf of Mexico. Upper ridging was currently centered over the local area. There was a line of thunderstorms associated with the trough over the western Gulf, but those are moving toward the Texas coast. Temperatures are quite a bit milder this morning with most locations seeing temperatures in the 60s at 3 am. SHORT TERM... Upper ridge and surface high will continue to move eastward today and Saturday, as the frontal system to the west moves out of the Rockies. This will allow surface winds to gain more of a southeasterly component, increasing moisture across the area. Current precipitable water values in the 0.7 to 0.8 inch range will effectively double by Saturday afternoon. An easterly wave moving around the periphery of the upper ridge will bring chances for showers to far southern portions of the area today and tonight. As the cold front and upper trough approach from the west on Saturday, there will be a better potential for showers and thunderstorms across the area. Best forcing will remain northwest of the area. Shear is rather limited, so, while a few storms could become strong, most should stay below severe limits. On Sunday, the upper trough and a surface prefrontal trough will approach the area. CAPEs around 1500, Lifted Indices of -6 and lapse rates around 6.5 should be conducive to some strong storms, but shear will remain weak and wet bulb zero values of nearly 13,000 feet should indicate a low, but not zero, threat of severe weather. Will carry likely to categorical POPs across the area on Sunday. The associated cold front looks to move through the local area overnight Sunday night, possibly as late as after sunrise Monday along the Mississippi coast. Could be some lingering rain patches behind the frontal passage going into Monday. Expect much above normal temperatures through the weekend, especially at night, with lows in the 70s for much of the area Saturday and Sunday mornings. No major differences in model guidance numbers prior to Sunday. Will trend a little toward the cooler guidance for highs on Sunday. 35 LONG TERM... Behind the front, a deep upper trough will cover much of the eastern half of the country for much of the first half of the work week. Early showers Monday will be the last substantive chance of rain until at least next weekend. Cold air will get reinforced Tuesday, making for a fairly cool middle of the week. Temperatures will return to near normal levels by Thursday or Friday. 35 AVIATION... VFR category conditions are generally expected at each of the terminals through the TAF forecast period. There will be small chances for convection to impact KHUM this afternoon and KHUM, KMSY and KNEW tonight. Patchy light fog may also affect the more fog prone TAF sites late tonight and early Saturday morning. 11 MARINE... Moderate to occasionally strong easterly flow will continue across the coastal waters through Saturday. This will result in exercise caution conditions that may flirt with small craft advisory criteria at times, at least over the open Gulf waters. The winds will ease and shift to the southeast Sunday in advance of a cold front that will move through the coastal waters Sunday night into early Monday. Moderate to strong offshore flow will develop in the wake of this front that will persist into the middle of the next work week. 11 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. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support. Orange = High Impacts; Slight to Moderate risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate risk of severe and/or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 84 65 84 70 / 0 10 40 30 BTR 85 69 85 72 / 0 10 60 40 ASD 84 69 84 73 / 10 20 50 30 MSY 84 72 84 74 / 10 30 50 30 GPT 83 70 83 73 / 0 10 30 30 PQL 84 68 83 71 / 0 10 30 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$