SPC Upgrades Portions Of Central Alabama To Moderate Risk On Sunday

The Storm Prediction Center has upgraded the severe weather risks across the state for Sunday, now introducing a MODERATE RISK (level 4 out of 5) for much of the southern half of Central Alabama. This includes locations south and west of a line from Memphis (Pickens Co.) to Clanton (Chilton Co.) to Cecil (Montgomery Co.) to Goshen (Pike Co.)

The ENHANCED RISK (level 3 out of 5) has been expanded northward to include locations along and south of a line from Millport (Lamar Co.) to Birmingham (Jefferson Co.) to just north of Woodland (Randolph Co.)

The SLIGHT RISK (level 2 out of 5) continues for locations above that to as far north as Guin (Marion Co.) to Oneonta (Blount Co.) to Pleasant Gap (Cleburne Co.).

The MARGINAL RISK (level 1 out of 5) continues for locations as far north as Russellville (Franklin Co.) to Priceville (Morgan Co.) to Fort Payne (Dekalb Co.).

Here is the latest Day 2 Severe Weather Outlook from the Storm Prediction Center:


SUMMARY: Numerous severe storms appear likely Sunday from east Texas to South Carolina. Several strong tornadoes may occur from parts of northeastern Louisiana into central/southern Mississippi and Alabama Sunday afternoon and evening. A swath of damaging winds and a continued tornado threat should also extend across Georgia and parts of South Carolina through Sunday night. Large hail is likely over much of the area as well.

East Texas into the Lower Mississippi Valley and Southeast: Mainly elevated storms posing an isolated large hail threat may be ongoing Sunday morning in a low-level warm advection regime across parts of MS/AL. This activity should spread eastward across AL into parts of central/southern GA through the day as a weak, low-amplitude shortwave trough shifts northeastward across the Southeast. There appears to be some potential for the southern flank of this activity to become surface-based by Sunday afternoon across parts of southern/central GA and vicinity. If this occurs, then all severe hazards appear possible.

Across the southern Plains, a shortwave trough is forecast to develop eastward through the day, eventually reaching the lower MS Valley by Sunday evening, and continuing eastward across the Southeast overnight. 50-70+ kt of mid-level flow attendant to this shortwave trough will overspread these regions. At the surface, a low will develop eastward across TX/OK to the lower MS Valley through the day while gradually deepening. A warm front should lift northward across parts of east TX into the lower MS Valley and Southeast in response. The greatest severe weather threat Sunday will likely focus along/south of this warm front. A cold front is also forecast to sweep east-southeastward through the period in tandem with the developing surface low.

Storms may form early in the period across parts of east TX as large-scale ascent associated with the shortwave trough overspreads an increasingly unstable warm sector. Steep mid-level lapse rates and strong effective bulk shear should support a threat of isolated large to very large (2+ inches) and damaging winds with any supercells that initially develop. With time, the airmass across the lower MS Valley downstream of this morning activity is forecast to quickly destabilize as the upper 60s to lower 70s surface dewpoints spread northward in tandem with the warm front and as diurnal heating occurs.

There is some concern about dominant storm mode, but effective shear of 50-60+ kt will easily support supercell structures. A 40-50+ kt low-level jet is also forecast to develop across parts of LA/MS and vicinity by peak afternoon heating. A corresponding increase in low-level shear combined with the strong deep-layer shear and moderate to locally strong instability suggests the potential for strong tornadoes with scattered supercells and clusters in a corridor extending from northern LA into southern/central MS/AL Sunday afternoon and evening. Scattered large hail and damaging winds, some of which could be significant, may also occur. Given the increased confidence in strong tornadoes occurring, a Moderate Risk has been introduced across this area.

The shortwave trough and strong low-level jet will shift eastward through the evening and overnight hours across AL into GA and parts of SC. Eventually, upscale growth into one or more clusters should occur. Both scattered damaging winds and a few tornadoes should be the main threats. A couple of strong tornadoes with embedded supercells within the cluster/line also appear possible across this region given the very strong low-level shear that will be present.

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