- Day Three
acus03 kwns 200721
Storm Prediction Center ac 200720
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0220 am CDT Thu Sep 20 2018
Valid 221200z - 231200z
..no severe thunderstorm areas forecast...
severe weather is not expected across the U.S. On Saturday.
As an energetic short-wave trough within the fast belt of polar
westerlies over the northern U.S. And Canada shifts across the
Maritimes and into the northwest Atlantic, a second trough within
this belt of flow will move inland across the Pacific northwest.
South of the main belt of flow, a weak trough is progged to move
slowly across the Southern Plains region, while several weak
disturbances move across the Ohio and Tennessee valleys through the
At the surface, the trailing portion of a cold front vacating the
northeastern U.S. Early in the period is forecast to remain
quasi-stationary, stretching from the mid-Atlantic region, across
southern Appalachians, to the arklatex area. The main southward
advance of the colder air north of this front should be limited to
portions of Texas and Oklahoma, west of a weak low progged to drift
very slowly eastward across the northeast/East Texas vicinity
through the period.
Scattered showers and thunderstorms are forecast along the
quasi-stationary front, but with the boundary south of the belt of
stronger flow aloft, little risk for severe weather is evident at
this time. Widespread convection is forecast across the
south-central U.S. -- From eastern portions of the Southern Plains
into the lower Mississippi Valley -- ahead of the weak upper system.
Here also, weak shear should preclude appreciable severe risk.