- 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