JD: 00-177 DoW: SAT /SUN UTC Date: 25JUNE2000

SUMMARY: Halo/Sprite During Dying Phase of Supercell over LMA

Excellent null case storms with extreme IC flash rates

TLE PREDICTION: 0.42 [0.7 x 0.60]

RESULTS: 1 Halo/Sprite Directly Over LMA

LESSONS: Follow supercells through dying phase

PERSONNEL: Lyons, Nelson, Fossum, Nordem,

STEPS STATUS: STEPS operates. Works until 04Z.

YRFS OPERATION LOGS: Full operations. Cells formed in eastern CO (some dry microbursts along Front Range) and moved eastward. Relatively limited upscale evolution was evident around sunset. Had reasonably rapid clearing of debris clouds and fair to good viewing through moonrise at 0730Z (which terminated LLTV operations). One supercell-like storm moved east-southeast from triple point of CO-KS-NE border. Had mostly +CGs, but extremely high IC rates (well over 1/sec for an extended period of time). As cell moved north of GLD it began weakening (after 0430Z). It the then briefly re-intensified around 0500, reaching 61 dBZ and 50 kft. It was rapidly re-weakening with CGs ending when it launched a single halo/sprite. While the radar echo was not that large, the cloud canopy was quiet extensive (though not especially high). This may have been with the last CG of the storm. The stratiform area was up to about 7500 km**2 at the time. Other cells over the next two hours produced spectacular IC flash displays. Could easily see illuminated towers from YRFS. Flash rates often greater than 1 sec (essentially continuous). The associated CG rates were quiet small. Did not focus on MCS in panhandle area because of both clouds and distance form LMA. Have excellent GEN III images of ICs from hot towers. Sampled VLF, PD, and PMT (only got VLF for sprite as tracker was on another cell at the time). No nowcasts issued. VLF signal was out during early part of tapings. Recycled tele LLTV tape.

STEPS OPERATIONS: STEPS goes for early ops. Coordinated radar scans were conducted mid afternoon on an isolated convective cell in the western dual Doppler lobe, and full coordinated operations with T28, mobile mesonets, electric ballooning units, and the hailstone van were conducted first on a small splitting cell just NE of S-Pol from 6:00 to 7:00 PM, and then on a larger supercellular storm which developed near Yuma and propagated eastward over Wray and Haigler NE between 7:00 PM and 9:00 PM. The later cells displayed reverse polarity, but initially did not produce much CG activity. However, the decaying supercell near Haigler produced extensive numbers of positive CGs between about 8:00 PM and 10:00 PM. Electric ballooning units had two successful launches on the supercell between Wray and Haigler. Scattered reports of hail up to 3/4 in were reported with these cells, but no strong surface winds. Coordinated observations were also taken with two DOW radars, which were located about 10 m N of Joes Co. and 10 m S of Cope Co. Mark Stanley operated interferometer. Also had Xybion trained on cell which produced sprite.

KEY RESULTS : Halo/Sprite directly above LMA

Total TLEs from Yucca Ridge This Campaign: 533

FMA

Red Xybion (A)-Patrol: 3 tapes

Sony TRV900 3CCD: shot TL scenes of clouds;

GEN III unit; 5 DV tapes w/ sprites; 3 S-VHS w/ GPS

JVC KY-19: shoot daytime TL/STEPS Cam (to ESE);

Pulnix CCD: shoot various TL scenes

Photodiode: Tested with several tubes and gains

Winckler PMT: sampled

GPS: OK

WWV Source: OK

VLF Inspire: sampled (signal out early in tapings)

ELF N-S: not available

ELF E-W: not available

NLDN Live: OK

NLDN Paper: 13 maps

NLDN Archive: 4 saves

MRC Data Acquisition: OK- many samples

FMA Data Acquisition: not available

Thunder Mic: available

LANL Tracker: OK

Red Xybion (B)-Zoom; 2 tapes (on tracker)

Red Xybion (C)-Tele: 0 tapes-on tracker

Blue Xybion(D)-zoom: 0 tapes - problems with focus

Mountain Cam: nominal

STEPS Cam: nominal

Shure Mic: OK

NEXRAD Archive: Revised EDIS; Many manual saves

GOES Archive: OK

RUC2 Archive: OK

STANFORD/STAR LAB:

Telescope a

LLTV a

ELF/VLF a

UTAH STATE UNIVERSITY: not present

MIT ELF: problems with vertical antenna?

FUELLEKRUG ELF: operational

ISRAELI ELF: nominal