Pre-frontal troughs and winshifts?

[Ed Lizard]

Where do the pre-frontal windshifts, that occasionally trigger storms ahead of the front down here in SE Texas, and more often prevent action along the front by shifting winds and reducing frontal convergence, come from?

Day old outflow boundaries?

Thinks like the Winter coastal front down here I can understand, dry line formation I can understand. I'm talking the windshift w/o appreciable difference in air mass.

[isohume]

Where do the pre-frontal windshifts, that occasionally trigger storms ahead of the front down here in SE Texas, and more often prevent action along the front by shifting winds and reducing frontal convergence, come from?

Day old outflow boundaries?

Thinks like the Winter coastal front down here I can understand, dry line formation I can understand. I'm talking the windshift w/o appreciable difference in air mass.

Prefrontal trofs can form in a variety of ways depending on the synoptic/meso mass/temp field setup.

There can be dynamic mechanisms external to the front, like interactions with fronts in the mid/upper levels, mlvl shortwaves tracking ahead of the front, interactions with lee trofs or dry lines, and frontogenesis ahead of the front if the airmass is not uniform enough in mass/temp.

Some internal forcings close to or within the front include: the degree of sfc friction depending on Vs, the alignment of along front temperature gradients --> close in waa --> rising air, evaporation of precip ahead of the front leading to cold pools aloft --> increased mlvl lapse rates, descent of air from aloft ahead of front (subsidence) --> sfc warming and a new temp gradient ("two" fronts), and ascent ahead of the front tilting the front forward and creating a tilted temp gradient atop the BL, which can then interact with sfc cold pools creating a prefrontal trof.

These aren't all the forcings/interactions possible, of course, and any combination of these are possible too.