- Day Three
acus02 kwns 201719
Storm Prediction Center ac 201718
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1218 PM CDT Monday Oct 20 2014
Valid 211200z - 221200z
..no severe thunderstorm areas forecast...
isolated thunderstorms are possible over parts of the interior
west...western and southern Texas...southern portions of the Florida
Peninsula...and perhaps over a portion of the northeastern states.
Upper trough over the eastern U.S. Is forecast to evolve into a closed
low as it moves eastward...reaching the middle Atlantic coast by the end
of day 2. Cutoff upper low circulation over northern Mexico should drift
slowly east toward western Texas during the day. Meanwhile...upper trough
now approaching the western U.S. Coast will continue through the central
and northern rockies.
At the surface a Lee trough will become established over the northern and
Central High plains...while a cold front accompanies western U.S. Upper
trough through the northern rockies. An occluded low will move through
the middle Atlantic and off the eastern U.S. Seaboard in association
with the evolving upper low over the eastern states.
..srn through central rockies area...
Plume of subtropical moisture will continue to advect northward ahead of
the progressive upper trough and in association with closed upper
low circulation over northern Mexico. Weak instability is expected as the
boundary layer warms and will promote scattered convection including
isolated thunderstorms over the higher terrain Tuesday and Tuesday
Cold air aloft accompanying the evolving upper low and ascent
associated with vorticity maxima rotating through this feature
should promote the development of weak instability and scattered
showers over the northestern states. Though instability will remain very
weak /generally at or below 300 j/kg/ it might become sufficient for
isolated thunderstorms within a more general area of scattered
showers during the afternoon.
Scattered showers and thunderstorms will likely develop within plume
of deep subtropical moisture and marginal instability that should
characterize the southern Florida pre-frontal warm sector Tuesday.