We've known for a long time (at least a decade) that the soaring
models and weather forecasts have number of problems which directly impact our
ability to set world records. For example, they generally do not predict the
morning over running, the early morning cumulus clouds. They admittedly are poor
with predicting cirrus and midlevel clouds that can affect the rates of climb.
They are sometimes poor at predicting the presence of cumulus clouds especially
in the conditions that we find in Texas with the moisture coming up from the
Gulf of Mexico.

We appear to be quite good with wind speed and direction. Their lift forecasts
are good except when we have large scale cirrus or mid level clouds (like last
Sunday). These two variables are of primary importance, but the presence of
cumulus clouds to mark the lift streets is key after these two variables are
forecasted to be the values that we need and they are in fact correctly
predicting the conditions for the day.

T-skew charts help, but only so much. We want to know if the morning cumulus
clouds will dry out as the cloud base rises. If there is a strong inversion and
a dry air mass above it, we would likely see the cu's disappear later in the
morning or afternoon, but that doesn't always seem to be the case.

Also t-skews along the many hundred miles of the course are difficult to
produce.

You can find out more here and at the links provide here:
http://www.drjack.info/BLIP/INFO/help.html.