970205H IOP11 (Flight 7) on Low 30 and Cold Front

Aircraft Involved: P-3, Electra, UK C-130, and G-IV

Summary Description of Mission:

The planned primary mission was a "systematic survey" of the cyclone and cold frontal region and rainbands associated with Low 30. The UK C-130 and P-3 were to join up on a survey of the low center around 0030 UTC, after the C-130 had completed several legs on the warm front farther east in support of Electra flight legs through the warm front. The G-IV was to make a "Figure 4" pattern on the low center with its first pass coincident with the first P-3 pass near 2330 UTC. The low was expected to be fairly deep (981 mb), with an extensive precipitation zone near the frontal zone, which was expected to have a good thermal and wind contrast at low levels.

The P-3 completed its first leg to the west at about 2350 UTC, cutting the leg a little short to insure getting to the meeting point with the C-130 on time. On the leg to the northeast the P-3 saw a dramatic wind shift near 0000 UTC indicating the location of the front. The P-3 and C-130 began coordinated flight legs at 0032 UTC and four legs were completed by 0430 UTC. On leg 1, the P-3 performed a descent "mini sounding" from 5,000 ft to 1,000 ft, then up to 8,000 ft to map the extent of the low-level jet ~100 km ahead of the precipitation band on the cold front. On leg 3, the P-3 performed another mini-sounding from 8k ft down to 1k ft, then return to 5k ft just on the warm air side of the frontal band. Saw winds of 75 knots at the jet maximum level of 3000 ft.

Communications:

1. No problems.

P-3 Equipment Problems Encountered:

1. None of note.

Coordination Problems

1. No problems of note.

Recommendations & Evaluation:

1. Excellent case of a strong cold front and low level jet. Well coordinated with C-130 dropsondes.

--Dave Jorgensen & Frank Roux