| srquirrely |
| (Weather Watcher) |
| Sun Jun 22 2008 05:24 PM |
|
WHAZZAT?
|
When you look at the visible satellite and see a semi-circular line of lower clouds spreading out from thunderstorms, what is that??? It seems like it would be clouds propelled by a downburst situation, but not low clouds, probably mid-level judging from the apparent temperature. Would it look like a roll cloud from the ground? There are a few of them out there right now... they move pretty rapidly out from the center of convection and sometimes persist quite far away from it so then it wouldn't look like part of the storm. And they don't appear to be affected by prevailing low or mid-level winds...
Just curious,
TIA
ADDS satellite TPA :
[url=http://adds.aviationweather.gov/satellite/displaySat.php?region=TPA&isingle=single&itype=vis]
Ed Dunham
|
| (Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)) |
| Sun Jun 22 2008 05:57 PM |
Re: WHAZZAT?
|
Its called a Gust Front - usually visible on radar. When a large thunderstorm cell or complex reaches its peak and begins to dissipate, all of that upflowing air that built up the storm begins to descend at an ever increasing rate as the storm weakens. When it hits the ground it fans out in a gust front. When the gust front passes over your location the temperature will often drop sharply and the winds can get quite gusty - sometimes gusting to 40mph. The temperature differential forms the low clouds - and sometimes the counterclockwise rotation can create a roll cloud. Because of the increased force from the downdraft of descending air, the gust front moves out ahead of the dying thunderstorms at a faster rate than the movement of the thunderstorm itself.
Cheers,
ED