Day 1 Severe Weather Outlook

Valid 181200Z – 191200Z


Scattered thunderstorms are expected from central Texas through the
Gulf States into the Carolinas. Organized severe is not forecast.


Late-evening water-vapor imagery depicts a short-wave trough
extending from AZ-northwest Mexico, shifting east in line with
short-range model guidance. 500mb speed max associated with this
feature is forecast to translate into northwest LA by 19/00z, then
into AL/GA by the end of the period. Despite this notable speed max,
negligible mid-level height changes will occur across low latitudes
and any large-scale forcing for ascent will be driven by
warm-advection processes. Although, frontal convergence should aid
thunderstorm activity through the period.

Latest model guidance is not particularly aggressive with
boundary-layer heating later today as moist profiles and significant
cloud cover are expected across the warm sector. Even so, a gradual
rise in surface dew points should contribute to surface-based
instability that should prove more than adequate for deep, moist
convection. Latest thinking is warm advection will encourage
isolated-scattered thunderstorms across the warm sector through the
period. Despite a strongly sheared environment the greatest chance
for some storm organization will be along the advancing cold front,
from northern LA to central AL, where low-level convergence should
be maximized. Forecast soundings suggest gusty winds would be the
greatest risk with this activity; however, low-level flow does not
appear particularly favorable, in addition to a marginal
thermodynamic environment.

..Darrow/Dean.. 02/18/2020


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