Hi could someone explain the difference between them and why a trough forms from a weakening trowal.

I understand a trowal as a trough of warm air aloft (I used to know the term occluded front, cold front catching up to a warm front in a system) and trough as a elongated area of low pressure. I've seen multiple times a trowal line turning into a trough line on the GFA. See linked files. Could someone explain the meteorology behind this?

thanks ollie

thx

ols500 wrote: ↑Mon Dec 19, 2022 7:31 pm Hi could someone explain the difference between them and why a trough forms from a weakening trowal.
… I've seen multiple times a trowal line turning into a trough line on the GFA.

I will have a guess: it’s marked as an occluded front (trowal) for as long as it’s associated with an adjoining warm/cold frontal system. Once the warm and cold fronts have dissipated, what’s left is noted as a trough rather than a front.