2018 Autumn/Fall Discussion (Northern Hemisphere)

The highest potential for impactful severe weather will likely exist

from southeast Texas towards the lower Mississippi Valley during the

evening and overnight. In conjunction with the aforementioned

low-level jet, channels of warm/moist low-level confluence streaming

north off the Gulf will probably encourage discrete development

ahead of a southwest/northeast-oriented line of strong/severe storms

moving east across the Sabine Valley during the evening. Forecast

soundings indicate ample low-level shear for stronger circulations

within both discrete/line-embedded supercells and QLCS structures,

with this potential likely maximized across portions of

western/central Louisiana and western Mississippi. Although

instability will be modest, enough low-level CAPE should be

available for a threat of tornadoes (a couple of which could be

strong) and damaging winds, especially considering surface dew

points in the upper 60s/lower 70s. Indeed, HREF guidance indicates

high probabilities of at least 500 J/kg of surface-based CAPE

extending to the Mississippi Delta. Considering this fairly

consistent signal from large-scale and hi-res guidance, the

Enhanced/Slight risks have been expanded eastward for a nocturnal

threat of tornadoes and damaging winds.