There is a threat for some strong thunderstorms on Tuesday, with a greater threat on Wednesday. On Tuesday, the threat will be mainly south of Cullman, and only a Marginal Threat (Level 1/5) for a severe thunderstorms. Gusty winds of 40-50 MPH and heavy rainfall will be the primary threat during this time.
On Wednesday, a more widespread and more intense chance for severe thunderstorms exists as a warm front moves north. Conditions will be favorable for large hail, damaging straight-line winds (70+ MPH), and tornadoes – one or two which could be strong.
- Round 1/2- Marginal Risk for severe storms mainly south of Cullman to Alexander City. Primary threats: small hail, gusty winds, heavy rain
- Round 2/2- Enhanced Risk for severe storms Coverage area-wide. All modes of severe weather possible, including damaging straight-line winds of 60-70 MPH, large hail, and tornadoes – one or two which could be strong. Timing: Beginning Wednesday afternoon lasting through the evening
- Flash flooding threat: minimal due to
…SUMMARY… A broad area of severe weather potential -- including risk for large hail, damaging winds, and several tornadoes -- is anticipated Wednesday from the Arkansas/Louisiana vicinity eastward across the central Gulf Coast states/southern Appalachians. …Synopsis… A vigorous upper low moving across central portions of the U.S. will once again be the primary upper feature of interest, as it tracks from the Texas/Oklahoma Panhandle vicinity early, to southern Missouri through the end of the period. Ahead of this system, moderately strong/accompanying flow will spread across the lower Mississippi and Tennessee Valleys and central Gulf Coast states with time. At the surface, a low is forecast to cross Oklahoma during the day, and then should cross the Ozarks through the evening eventually reaching the western Illinois vicinity by 18/12Z. Widespread thunderstorms, and substantial/accompanying severe risk, can be expected in advance of this system. …The AR/LA vicinity eastward to portions of TN/GA and the FL Panhandle… Showers and thunderstorms are forecast to be ongoing from Kansas southward to Texas ahead of the advancing upper system and associated cold front, and eastward across the central Gulf Coast states in a zone along a west-to-east warm front. Some ongoing severe risk will likely exist at the start of the period. With time, as moisture streams northward from the Gulf of Mexico beneath steepening lapse rates, modest heating will push surface-based CAPE into the 1000 to 2000 J/kg range with a broad warm sector stretching from the AR/LA vicinity eastward to the southern Appalachians. Convection is forecast to increase in response to the destabilization, as persistent UVV occurs not only in the vicinity of the cold and warm fronts, but also more broadly within the general warm-advection regime. Southerly low-level flow, veering and increasing to around 50 kt from the west/southwest at mid levels will provide shear favorable for supercells. Additionally, ample low-level shear is expected to evolve through the day -- particularly near the aforementioned warm front which should drift northward across Arkansas and align west-northwest to east-southeast from far southern MO to central GA by early evening. As such, tornado risk may be maximized near this boundary -- across the AR area during the day, and then later increasing eastward across AL and perhaps into GA as well, as low-level flow increases into the evening/overnight. In addition to tornado potential -- including the risk for a couple of significant tornadoes across a broad area represented by the ENH/30% risk area, large hail and damaging winds will also occur in some areas. Risk will continue through the overnight hours, tapering from west to east across the lower Mississippi Valley but continuing across the central Gulf Coast states and into the southern Appalachians through 18/12z.