SPRITES 99 YUCCA RIDGE FIELD STATION
FMA Research
JD 99224 12 AUGUST 1999
PRELIMINARY SPRITE LOG
The following is a very preliminary listing of the times of sprites imaged at the
Yucca Ridge Field Station. These are based solely on real-time visual inspection of
the video monitoring system. There are most likely some additional sprites not listed
and not all those below may in fact be sprites. All times are UTC. Times are likely
to be within ±5 seconds of actual time.
SUMMARY: A deep short wave moved through the northern plains generating a cyclonic
storm system. A complex convective pattern was spawned by the cyclone, which included
widespread rain showers with embedded severe cells in SD and ND. A tornado watch was
issue during late afternoon. The system generated a large though not exceptionally cold
cloud shield. Another MCC formed over Iowa in the late afternoon and remained quasi-stationary
during the night. Combined flash rates were over 12,000/hr at times. Percent positive
values were generally below 10%. YRFS could not see the Iowa storm due to intervening
clouds, and concentrated on the SD-ND system. It had a large region of stratiform rain
with scattered +CGs and produced a moderate number of sprites and several elves. Viewing
conditions (clear sky, no moon) were about as good as they get. A number of sprites were
observed coming from below the horizon at 800+ km range. Activity slowed to near zero
after 0800Z, as the storm weakened (and also moved further away). In spite of the large
area of precipitation, no "dancer" sprites were noted.
There were naturally many Persied meteors, approaching 30/hr in our cameras.
The balloon mission was scrubbed due to local storms. Custer should have had clear views
of both storms. The MM5 forecast run ran without problems.
Total TLEs from Yucca Ridge This Campaign: 1627
(S) = Sprite; (E) = Elve; (B) = Blue Jet; (CF/CG) = Cloud/Ground flash; (M)=Meteor
JD 99224 12 AUGUST 1999
0300 Start LLTV Observations
0438.47 [S]
0444.26 [S+]
0446.35 [S]
0447.59 [S?]
0455.05 [S-]
0506.27 [E]
0521.41 [S+]
0535.05 [S-]
0554.55 [E]
0557.05 [S+]
0600.24 [S-]
0604.24 [S-]
0606.52 [S]
0609.03 [S]
0610.50 [S]
0613.07 [S]
0615.23 [S]
0618.30 [S+]
0621.18 [S-]
0625.45 [S]
0634.31 [E]
0707.XX [S]
0708.50 [S]
0715.10 [S-]
0718.09 [S+]
0729.35 [E]
0735.40 [S-]
0742.10 [S]
0745.20 [S?]
0757.11 [E]
0830 End LLTV Observations