Thunderstorm movement

[flyboyzz1]

Does the anvil move forward or is that the back end. I have two conflicting books that show it both ways....

 

[Way2Broke]

The anvil typically shows the direction of movement. The anvil shaped top is formed by the upper level winds shearing off the top of the storm. The way I understand it, is that these winds are what limit the vertical development of the storm.

 

[kansas]

The anvil typically shows the direction of movement. The anvil shaped top is formed by the upper level winds shearing off the top of the storm. The way I understand it, is that these winds are what limit the vertical development of the storm.

Agreed. That's what I found during weather mod, anyway.

 

[avbug]

Upper winds don't shear off a convective cell. The cell is formed by differential temperature. The vertical progression of the cell is stopped by either an inversion that limits the cell by altering the decrease in ambient temps, or by the internal limits of of the rising parcel of air. It may also be topped, and frequently is, by a change in the relative humidity.

In other words, the cell either peters out because it becomes thermally exhausted, or it's stopped by a change in the atmospheric lapse rate. The wind doesn't blow it over or cut it off, excepting the wind itself is sufficiently sheared in temperature or relative humidity.

The anvil represents blow-off from the top, and doesn't indicate cell movement. It indicates the direction of the shear at the top. The anvil points only in the direction of the wind at the top of the anvil.

Remember that a cell doesn't blow with the wind. Wind is constantly moving through a cell. The wind is moving faster than the cell is, and in different directions and diferent altitudes. The cell isn't a captive body air moving up and down, but but a body of moisturethrough which the wind blows. Where it's vertical development stops, the debris field moves with the wind at that level. In many cases, debris fields can be seen at other levels too,and may be seen to move in different directions.

 

[Seadogrun]

The reference material that I have read shows movement in the direction of the anvil.

 

[avbug]

Again, at that altitude, yes, that's where the shear axis is...or where the wind is blowning. But not necessarily any place else, nor does it indicate the direction of movement of the cell. Only the debris field at that altitude. Winds may be expected from different directions at different altitudes, and the storm movement may be in an entirely different direction.

 

[Say Again Over]

All I know is that it is not a good idea to fly through the overhang.

 

[ksu_aviator]

With a few exceptions, (in the continental US) all frontal systems and thunderstorms move in a westerly direction. Winds aloft at altitudes where the anvil forms almost always run in a westerly direction. The sheer Avbug talks about is at the tropopause. That is where lapse rate, winds and pressure all change very dramatically.

So, as a thunderstorm builds to heights near the tropopause, the moisture that is carried up gets blown out to the west, forming the anvil. That is also the general direction of the movement of the storm. What to watch out for is the continuing build up beyond the anvil. That storm will have tremendous power and is likely to produce some hail and tornadic activity.

 

[avbug]

On the grand scheme of things, cells move east. However, locally cells can move in any direction, including westbound.

Directly adjacent to the cell beneath the "overhang" or anvil isn't a good place to be, as storm products may be exhuasting there, however, the debris field by itself, with adequate distance from the storm, isn't dangerous by itself. Debris fields can extend hundreds of miles downrange, in some cases.

 

[regionalcap]

With a few exceptions, (in the continental US) all frontal systems and thunderstorms move in a westerly direction. Winds aloft at altitudes where the anvil forms almost always run in a westerly direction. The sheer Avbug talks about is at the tropopause. That is where lapse rate, winds and pressure all change very dramatically.

So, as a thunderstorm builds to heights near the tropopause, the moisture that is carried up gets blown out to the west, forming the anvil. That is also the general direction of the movement of the storm. What to watch out for is the continuing build up beyond the anvil. That storm will have tremendous power and is likely to produce some hail and tornadic activity.

Most systems and storms move easterly not westerly.