Moisture Depth

Feb 5, 2004
Celina, Ohio
Is the 850 mb Td (9C or higher) the indicator for depth of the good moisture ? Is there anything else to look at when evaluating available moisture and its depth on a potential chase day ? Thanks

Jon Miller
RE: moisture using 850mb analysis

The 850mb level is a good place to start when assessing moisture depth. However, you will often find that the moist layer does not extend up to 850mb. It is best to augment your analysis of this level with 12Z sounding analysis; and surface and 925mb analysis. Get into the habit of examining all of the morning soundings in the forecast region to get a feel for the depth and quality of the moisture. The vertical distribution of dew point is important, both in the moist layer and in the elevated mixed layer. In addition to determining the amount of moisture in the parcel available for convection, depth is also very important in forecasting motion of weather features. For example: how fast a dryline might mix eastward during the day as a result of the moist layer mixing out in response to daytime heating (insolation).

- bill