323 FXUS64 KMOB 161809 AAA AFDMOB Area Forecast Discussion...UPDATED National Weather Service Mobile AL 1209 PM CST Thu Feb 16 2023 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE... Regional surface observations show a surface low pressure system lifting across southern IL/IN late this morning ahead of a positively tilted upper level trough moving across the central Plains and adjacent Upper Midwest. An associated surface cold front extends southward along the Mississippi Valley and into central portions of LA late this morning. A warm and moist southerly flow pattern prevails across our forecast area well in advance of the front this morning with temperatures warming into the lower 70s across southeast MS and interior southwest AL, and a little warmer in the mid to upper 70s across much of the remainder of the region. Surface dewpoints also range from the lower 60s across south central AL and in the mid 60s to near 70 degrees across much of southeast MS/southwest AL and along coastal areas. Ascent ahead of the lifting trough and approaching cold front is currently spreading along and east of the Mississippi Valley late this morning, and regional radar imagery shows convection increasing in areal coverage across LA and MS. A few showers and storms have developed as far east as interior portions of southeast MS and southwest AL as of 1130 AM CST. Attention will become focused across our southeast MS and interior southwest AL counties as we go into the early to mid afternoon hours as ascent continues to spread over this portion of our CWA. The latest high resolution guidance continues to show an axis of higher instability with associated MLCAPE values between 1000-1500 J/KG spreading into areas along and west of a Camden to Mobile line by 3 PM CST. Temperatures should continue to warm into the mid to upper 70s over our northwestern zones, which should any ongoing low level inversion. Effective 0-6 km bulk shear values of 45-55 kt and 0-1 km values of 25-30 kt will be in place across central and western portions of the CWA this afternoon, which will more than favor organized convection. 0-1 km SRH values around 150-200 m2/s2 are also expected to become oriented across interior southeast MS and southwest AL by mid afternoon. Convective clusters will likely develop over southeast MS/interior southwest AL through the early to mid afternoon hours, and we will also need to monitor for potential discrete supercells given the environment mentioned above. It appears locations especially along and northwest of a Wiggins-Leakesville-Coffeeville line will need to monitored for a damaging wind/tornado threat as we go into mid-afternoon. CAPE/shear profiles will support stronger updrafts that may also bring a hail threat to these areas. /21 && .PREV DISCUSSION... /issued 559 AM CST Thu Feb 16 2023/ ..New AVIATION... AVIATION... (12Z TAFS) Issued at 540 AM CST Thu Feb 16 2023 IFR to low-end MVFR ceilings are expected to remain in place across the region throughout the day. The exception being the BFM TAF site where early morning sea fog is currently resulting in VLIFR ceiling and LIFR visibility. However, this conditions will eventually improve through mid morning. Showers and thunderstorms are expected to develop out ahead of a cold front during the late morning/early afternoon hours today. A few thunderstorms during the afternoon and evening could become strong to severe across much of the area; capable of gusty/damaging winds, tornadoes, and hail. Some of the heavier activity will also bring brief reductions in visibility. Southerly surface winds around 15 knots with frequent gusts into the 25-30 knot range will occur from mid morning through much of the evening. Areas of LLWS (210 degrees at around 45 knots) are expected this evening over the inland areas as surface winds lower slightly. The surface winds will then shift northwesterly late this evening through the overnight hours in the wake of a strong cold front. /22 PREV DISCUSSION... /issued 508 AM CST Thu Feb 16 2023/ .New NEAR TERM, SHORT TERM, LONG TERM, MARINE... NEAR TERM... (Now through Friday) Issued at 504 AM CST Thu Feb 16 2023 The flow pattern aloft will remain southwesterly over our region through tonight between upper high pressure centered over the Bahamas and a large mid/upper level positively-tilted upper trough situated over the central Conus that will shift very slowly eastward. A 100-125 kt southwesterly 500 mb jet is expected to develop along the southeastern periphery of the trough axis. A surface low pressure area across northwest Arkansas will lift northeastward to the lower Great Lakes by midnight, with an associated cold front reaching the Mississippi River around noon today. Plenty of atmospheric moisture will already to established ahead of the system, with surface dewpoints in the mid 60s and PWATs ranging from 1.5 to 1.8 inches. Low level winds will strengthen in advance of this system today, with a 30-40 kt 850 mb jet spreading across the area. The cold front will then pass through the forecast area tonight. There are two parts to this event, with the first being discrete supercells that will develop ahead of the cold front starting early this afternoon across southeast Mississippi and inland southwest Alabama. These supercells will expand eastward through the remainder of the afternoon and evening hours. The atmosphere will become increasingly buoyant during the afternoon with MLCAPE values potentially topping out near 1300 J/KG. The moderate instability aligned with the strong deep layer and low level shear moving into our area during the day will result in strong to severe thunderstorms that will impact much of our forecast area this afternoon and evening, and cold linger a few hours past midnight southeast of I-65. Forecast soundings show moderate curvature to low level winds fields with 0-1 km storm relative helicity values ranging between 150-300 m2/s2. The thermodynamic and dynamic environment will be supportive of tornadoes (a strong tornado cannot be ruled out across our northwest counties), damaging wind gusts, and hail one inch in diameter or larger. The main QLCS/convective line is then expected progress eastward across our forecast area around mid-evening through much of the night within a forced region of ascent ahead of the cold front. Any any organized cells within the QLCS will be capable of damaging wind gusts and a brief tornado or two. The SPC outlook has and Enhanced Risk of severe weather across the inland portions of southeast Mississippi and southwest Alabama today and tonight, with a Slight Risk of severe weather across the remainder of the forecast area. This strong to severe storms will then taper off from west to east after midnight as the cold front passes through, followed by drier and cooler conditions on Friday. /22 SHORT TERM... (Friday night through Saturday night) Issued at 504 AM CST Thu Feb 16 2023 Cool, dry conditions will be in place across the region during the short term as an upper-level ridge quickly pushes across the southeast US and a large surface high builds over the Tennessee River Valley. With subsidence in place from the ridging overhead and PWATs near or below 0.5 inches, no rain is anticipated through the period. Lows Friday night will range from the upper 20s north to the mid 30s along the coast. Highs on Saturday will only rise into the mid to upper 50s. Lows Saturday night drop back into the mid to upper 30s, with low 40s along the coast. A MODERATE risk of rip currents Friday night will become a LOW risk for the weekend. /96 LONG TERM... (Sunday through Wednesday) Issued at 504 AM CST Thu Feb 16 2023 Zonal flow aloft will be in place through Tuesday as our region becomes situated between an upper ridge over the southern Gulf of Mexico and upper troughing over the northern half of the US. Upper flow turns southwesterly Tuesday night into Wednesday as a southern stream shortwave trough over Mexico ejects northeastward. One or two weak, embedded, shortwave impulses may also push through the flow out ahead of the main trough. At the surface, high pressure continues moving eastward into the western Atlantic. Additionally, a second high builds over the eastern Gulf/Florida Peninsula on Monday and also shifts eastward through midweek. With these highs to the east of our region, surface winds will turn more southerly/southwesterly, allowing for warm, humid air to advect in from the Gulf. Subsidence from these highs, however, should keep rain out of the forecast through Tuesday. Isolated to widely scattered showers return Tuesday night for the northern half of our CWA as the upper shortwave impulses push across the Tennessee River Valley. By Wednesday, isolated to scattered showers and possibly a few thunderstorms will be possible across the entire area as the shortwave trough ejects northeastward. At this time, although moisture, instability, and shear will be on the increase, the best forcing looks to remain just to our north and west. However, if future trends bring the ejecting shortwave closer to our region, then not only will the convective coverage increase, but the potential for strong to severe storms may also increase. We will continue to monitor trends over the coming days. Temperatures will quickly warm through the period, with highs possibly reaching the lower 80s in some interior spots by Tuesday and Wednesday. /96 MARINE... Issued at 504 AM CST Thu Feb 16 2023 Reduced visibilities from dense fog is expected over Mobile Bay, Mississippi Sound, and the Alabama nearshore waters through mid- morning. A light to moderate onshore flow will persist through this evening ahead of our next storm system. Moderate to strong northerly flow will then follow in the wake of a cold front late tonight and persist into Saturday morning. A Small Craft Advisory has been issued for the all marine zones during this period. A northeasterly flow will then decrease throughout the day Saturday, shifting to a mainly light westerly to southwesterly flow early next week. /22 && .PRELIMINARY POINT TEMPS/POPS... Mobile 46 53 32 56 38 65 49 73 / 90 30 0 0 0 0 0 0 Pensacola 52 59 36 57 43 65 52 71 / 80 40 0 0 0 0 0 0 Destin 54 62 39 59 47 65 55 71 / 60 30 0 0 0 0 0 0 Evergreen 47 54 30 59 36 67 44 75 / 90 40 0 0 0 0 0 0 Waynesboro 42 51 29 56 35 65 45 74 / 90 10 0 0 0 0 0 0 Camden 44 51 29 56 36 65 44 74 / 100 30 0 0 0 0 0 0 Crestview 53 59 32 60 37 69 44 75 / 80 30 0 0 0 0 0 0 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...High Rip Current Risk through Friday afternoon for ALZ265-266. FL...High Rip Current Risk through Friday afternoon for FLZ202-204- 206. MS...None. GM...Small Craft Advisory from midnight tonight to 3 AM CST Saturday for GMZ630>636. Small Craft Advisory from midnight tonight to 9 AM CST Saturday for GMZ650-655-670-675. && $$ This product is also available on the web at: www.weather.gov/mob