KEWX (Austin/San Antonio):
.LONG TERM (Sunday through Friday)...
As the longwave trough moves into the Rockies, cyclogenesis on the
High Plains will quickly strengthen, resulting in a strong response
of southerly return flow. This will bring a big change in boundary
layer humidity by Sunday afternoon.
A short wave trough passing through the longwave trough will eject
into Texas Sunday night. When combined with the typical strengthening
of the diurnal low-level jet, there are good chances for elevated
convection early over our area. CAPE values are moderate in the
750-1000 J/kg range, but mid level lapse rates should support hail.
In addition, low level shear is quite strong, especially in the
framework of 0-1 or 0-3 km SRH of 200-300 m2/s2. So if any storms can
become rooted to the surface, there could be an overnight/early
morning tornado threat.
The prospects for convection later in the day on Monday will hinge on
what occurs earlier in the day. But the projection of the initial
storms waning and leaving a minimally disturbed boundary layer leads
to anticipation of the cold front/dry line forcing a line of severe,
linear convection Monday afternoon to late evening. These storms
would have less instability and shear, but be rooted at the surface,
and potentially be more of a damaging wind and tornado threat.
https://forecast.weather.gov/product.php?site=EWX&issuedby=EWX&product=AFD&format=CI&version=1&glossary=1