- Day Three
acus02 kwns 260547
Storm Prediction Center ac 260546
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1246 am CDT Mon Aug 26 2019
Valid 271200z - 281200z
..there is a marginal risk of severe thunderstorms from northwest
Texas/southwest Oklahoma southeastward into western Louisiana...
Isolated severe thunderstorms are possible from northwest
Texas/southwest Oklahoma southeastward into western Louisiana on
Maturing mid-latitude cyclone, centered near the southern
Manitoba/Ontario border early Tuesday morning, is expected continue
eastward into far northwest Ontario. Expansive cyclonic flow
throughout the base of this system (and attendant enhanced westerly
flow aloft) will also progress eastward over the Upper/Middle MS
valleys into the Ohio Valley.
Surface low attendant to this upper system is expected to be
centered over northwestern Ontario Tuesday morning. A cold front
will extend southeastward from this low into the upper Great Lakes
then southwestward through the middle MS valley into southwest Texas.
Northern/eastern portion of this front will remain progressive,
continuing eastward through the Ohio Valley and lower Great Lakes.
Southern/western portion of this front will be less progressive with
outflow from an mesoscale convective system likely becoming the effective boundary across
southern OK/northern Texas.
..far northwest Texas/southeast OK into western la...
Showers and thunderstorm will likely be ongoing at the beginning of
the period as a decaying mesoscale convective system moves into the region. Isolated
damaging wind gusts are possible with the strongest cells along the
Warm and moist conditions are anticipated south of the composite
outflow boundary Tuesday afternoon. Mid-level temperatures will be
relatively warm, but the warm and moist low-levels will likely
result in an erosion of any convective inhibition. Convergence along
the boundary will then lead to thunderstorm development. However,
given the mesoscale nature of this boundary, its location is hard to
ascertain with much confidence at this point. Most of the
convection-allowing guidance suggests a more southerly boundary
location during the afternoon and the 5% threat area was adjusted
The lack of stronger vertical shear suggests minimal storm
organization and a predominantly multicellular Mode. Even so, strong
water-loaded downbursts are possible with the strongest updrafts.
A shortwave trough embedded within the base of the larger parent
mid-latitude cyclone is expected to move into the region during the
afternoon. Cool mid-level temperatures and large-scale forcing for
ascent associated with this trough will led to thunderstorm
development. Given the weak instability, storms are generally
expected to remain sub-severe with some small hail possible within
the strongest updrafts.
..maximum risk by hazard...
Tornado: 2% - marginal
wind: 5% - marginal
hail: 5% - marginal