961 FXUS64 KMOB 231731 AFDMOB Area Forecast Discussion National Weather Service Mobile AL 1231 PM CDT Tue Apr 23 2019 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION... 18Z issuance...VFR conditions expected through the forecast. South to southeast winds around 10 knots this afternoon become more light and variable overnight tonight. Patchy light fog will be possible late tonight into early Wednesday morning, mainly over inland areas. Visibilities generally remain 3SM or better. /49 && .PREV DISCUSSION... /issued 506 AM CDT Tue Apr 23 2019/ NEAR TERM /Now Through Tuesday night/...An upper ridge stretching north along the Mississippi River Valley will bring another day of high temperatures rising above seasonal norms. Tonight, a return of near seasonal lows are expected, with increasing cirrus coverage helping to limit overnight cooling. With boundary layer moisture on a slow increase the last few days, am expecting enough radiational cooling tonight, though, for patchy fog to form after midnight, so have added to the forecast. /16 SHORT TERM /Wednesday Through Thursday night/...Weak shortwave ridging aloft within an otherwise mainly zonal flow pattern will prevail across the north central Gulf Coast region Wednesday through Wednesday evening. The mid level flow pattern will then transition southwesterly across our area by late Wednesday night in advance of a deep trough that will be advancing across eastern portions of Oklahoma and Texas. A surface ridge of high pressure stretching from the north central Gulf Coast region through the Florida peninsula and the adjacent western Atlantic Wednesday will meanwhile slowly shift eastward through Wednesday night, allowing for a continued low level southerly flow across our region. A dry weather pattern will continue through Wednesday evening underneath the weak shortwave ridging aloft. Weak layer moistening and isentropic ascent underneath increasing southwesterly flow aloft could result in very isolated light rain showers after midnight Wednesday night and toward the early Thursday morning hours over portions of southeast MS and adjacent far southwest AL. We otherwise expect partly sunny skies on Wednesday, with increasing cloud cover over the region into Wednesday night. Highs Wednesday warm to 80-85 inland, with upper 70s along the coast. Lows Wednesday night range in the upper 50s to lower 60s inland, with mid 60s along the immediate coast. The next round of active weather is expected to impact our forecast area Thursday into Thursday night. The aforementioned upper level trough is forecast to translate eastward across the Mississippi Valley region late Thursday afternoon into early Thursday evening, before progressing across our forecast area Thursday night into early Friday morning. An associated area of surface low pressure located in the vicinity of east Texas and western portions of Louisiana Thursday morning is forecast to move eastward toward our forecast area Thursday evening, then east of our region by Friday morning. The latest guidance continues to differ on the exact track of the low, but with this feature potentially crossing over or near our forecast area, there is indication that a weak warm front may stretch over our forecast area late Thursday afternoon into Thursday evening prior to the passage of the surface low. A low level jet may become enhanced near and to the south of this boundary, with 35-45 knots of 850 mb flow developing across portions of southeast MS and adjacent southwest AL. The NAM and GFS also show a rather unstable airmass developing south of the boundary late Thursday afternoon into Thursday evening, especially over portions of southeast MS and southwest AL, and possibly into portions of the western FL panhandle, where MLCAPE values may increase to 800-1300 J/KG. Deep layer moisture and ascent ahead of the approaching upper trough and surface low pressure system will bring numerous to widespread showers and thunderstorms across our forecast area late Thursday afternoon into Thursday night. Some of these storms could be strong to severe, especially where instability and shear become maximized in the vicinity of the boundary if does indeed stretch over our area. The new Day 3 outlook from SPC includes much of our area in a Marginal severe risk Thursday afternoon and evening, with the Slight risk extending into far southwestern portions of our area in southeast MS. We will monitor later guidance to determine if the Slight risk will need to be expanded farther east in our area. We will introduce the isolated severe threat in our early morning graphics and Hazardous Weather Outlook. For now it appears the main hazards will be damaging wind gusts and perhaps a tornado. /21 LONG TERM /Friday Through Monday/...A lingering low chance of rain showers will persist mainly across eastern portions of our CWA Friday morning, before a much drier airmass spreads across our region by Friday afternoon in the wake of the passing upper level trough and associated surface front. A dry northwest to zonal flow pattern looks to prevail into the weekend, and will maintain a dry forecast Saturday and Sunday. Upper ridging may build into our region early next week, maintaining the dry pattern into Monday. Warm days and mild nights should persist through the extended forecast period. /21 MARINE...A surface ridge over the region will bring a light onshore flow to area waters today. As an upper system approaches from the west into Thursday, onshore flow will strengthen, bringing building seas late Wednesday through Thursday. As the system passes Thursday through Thursday night, strong storms can bring locally strong winds along with greatly reduced visibilities in very heavy rain. A post-system cold front crosses area waters Friday, bringing a moderate to at times strong offshore flow to area waters into Friday night before easing late Friday night into Saturday. A Small Craft Advisory will likely be needed for Thursday into Friday night. A light onshore flow returns Saturday, and is expected to last though the weekend. /16 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob