U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus02 kwns 220534 
Storm Prediction Center ac 220533 

Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1133 PM CST Thu Feb 21 2019 

Valid 231200z - 241200z 

..there is an enhanced risk of severe thunderstorms from southeast 
Arkansas/northern MS to western Tennessee... 

Scattered severe thunderstorms are expected to form along a corridor 
from the lower Mississippi Valley into portions of the Tennessee 
Valley. Damaging winds and tornadoes are possible. 

..lower MS valley to Tennessee Valley... 

Late-evening water vapor imagery depicts a well-defined upper low 
near the lower Colorado River valley. This feature is forecast to eject 
into the Southern Plains by the start of the day2 period then lift 
into the mid MS valley by mid day Saturday as an intense 500mb speed 
Max translates across OK into MO. Mid-level speed Max will shift 
into western PA by Sunday morning. Impressive 12hr 500mb height 
falls will spread across the southern High Plains into MO with the 
southern extent of large-scale forcing for ascent expected to glance 
the enh risk region. 

Latest model guidance suggests this low-latitude system will induce 
a Lee surface low over northeast nm late Friday. Surface low should 
track along the Kansas/OK border before ejecting northeast into 
southeast Iowa by early evening. In response to this developing 
cyclone, higher-precipitable water air mass will surge inland as a warm front lifts 
across the arklatex ahead of a surging cold front. Latest NAM 
guidance is not as aggressive with destabilization from eastern OK 
into Kentucky due to a slower advancing warm front. Have adjusted northern 
severe probabilities to reflect the possibility that buoyancy, and 
certainly surface-based instability, may be retarded at higher 
latitudes. Forecast shear profiles are impressive and supportive of 
organized severe convection. At this time it appears severe 
convection should evolve along the advancing cold front with 
supercells possible prior to possible squall line development. 
Discrete pre-frontal storms may develop which could have a 
proclivity to produce tornadoes if surface-based instability 
materializes as expected across the enh risk, and surrounding areas. 
Severe threat will migrate into the Tennessee Valley and central Gulf 
states during the latter half of the period. In addition to the 
tornado threat, damaging winds are likely with the frontal 

..maximum risk by hazard... 
Tornado: 10% sig - enhanced 
wind: 30% - enhanced 
hail: 15% - slight 

.Darrow.. 02/22/2019