Pressure jump at launch

The difference between the first pressure value reported by the sonde after
launch (949.7) and the reported surface pressure (943.7) is somewhat larger
than expected.  As a result, the absolute altitudes for this sounding and
the ascent rates for the first 30 seconds are questionable.

Because these pressure jumps appear in clusters at B4 and do not appear
all the time, I am beginning to think that there may be an operational
problem.  Perhaps too much time is elapsing between the time the system
is ready for release and the balloon is let go. Site ops will be notified.

• Relative Humidity (hybrid-b grid)(rh)
• North Latitude(lat)
• base time in epoch(base_time)
• Dry Bulb Temperature(tdry)
• Wind Direction(deg)
• Retrieved pressure profile(pres)
• lon(lon)
• Ascent rate(asc)
• Wind status(wstat)
• Wind Speed(wspd)
• Dewpoint Temperature(dp)
• -180.0 - +180.0(alt)
• Time offset from base_time(time_offset)

• Easterly Wind Component(u_wind)
• Dry Bulb Temperature(tdry)
• Retrieved pressure profile(pres)
• -180.0 - +180.0(alt)
• Ascent rate(asc)
• Dewpoint Temperature(dp)
• Wind Direction(deg)
• Relative Humidity (hybrid-b grid)(rh)
• Wind status(wstat)
• base time in epoch(base_time)
• Wind Speed(wspd)
• lon(lon)
• V wind component(v_wind)
• Time offset from base_time(time_offset)
• North Latitude(lat)