IOP 2, 07-08 Jan 2001

IOP 2: 07-08 January 2001

Time Period of IOP

        1400 UTC 07 Jan 2001- 1900 UTC 08 Jan 2001

Overview of IOP

 An occluded frontal band was forecast in the study area for Sunday. An Convair-580 doors close time of noon local was set and retained until shortly before the flight, when it was decided to hold the flight until 2 pm local time because the expected rainband had not yet appeared on the radar screen, although satellite imagery showed two distinct north-south oriented cloud bands approaching the Washington coast slowly from the west. The Convair-580 finally took off  from Paine Field at 3 PM local time. Off the coast, the Convair-580 intercepted a weak but well-defined rainband ahead of the surface trough, that seemed to correspond with a recent MM5 model forecast. Several legs were flown from the surface to 21,000 ft. The  S-Pol radar was operated through Sunday night to observe the onshore movement of the rainband and trailing surface trough wind shift.


Convair-580 Summary

UW Flight Number:


Period of Flight :

    2300-0500 UTC, 7-8 January

Main Accomplishments of Flight:

    Measurements in light precipitation from a warm occlusion-type system.

Instrument Problems:

    PMS 2-D cloud probe.  SPEC CPI and PMS 1-D cloud probe not aboard.

Flight Scientist:

    Peter Hobbs

Approximate UTC Timeline (Local time = UTC – 8 hours) Activity for UW Flight 1847

2300 Engines on.

2311 Take off from Paine Field

2311-0025 Transit to Point A (about 100 nautical miles southwest of Westport).

0035-0045 A to  B at 12,000 ft.

0045-0049 Climb to 15,000 ft at B.

0049-0058 B to A at 18,000 ft.

0058-0105 Climb to 18,000 ft at A.

0105-0120 A to B at 18,000 ft.

0120-0127 Climb to 21,000 ft at B.

0129-0140 B to A at 21,000 ft.

0140-0148 Descend to 15,000 ft at A.

0148-0200 A to B at 15,000 ft.

0200-0218 Descend to 10,000 ft at B then to new B location (45 deg 40'/126 deg 0').

0218-0234 B at A at 10,000 ft.

0234-0242 Descend to 7,000 ft at A.

0242-0307 A to B at 7,000 ft.

0307-0311 Descend to 5,000 ft at B.

0311-0335 B to A (46 deg 30'/124 deg 45') at 5,000 ft.

 (Lost radio contact with S-Pol radar between 7,000-5,000 ft at ~100 miles out from radar.)

0335-0340 Descend to 3,000 ft at A.

0340-0345 A to B at 3,000 ft.

0345-0348 Climb to 4,000 ft, still heading to B.

0348-0356 Continue toward B at 4,000 ft, but leg cut short due to fuel.

0356 Back toward Westport at 2,000 ft.

0416-0500 Return to Paine Field via Olympic Mountain transect (clouds east of Olympics).

0500 Engines off.

S-Pol Radar Summary

1400 UTC Sun 07 Jan:
Radar switched from dual-pol to long-range mode.

Scan cycle switched from NWS-Surveillance to Long Range

   (with RHIs after 2314 UTC).

Radar down for testing 2330-0000 UTC.

0300 UTC Mo 08 Jan:

Radar switched from long-range to dual-pol mode.

Scan cycle switched from Long Range to Research.

1900 UTC Mo 08 Jan:

Scan cycle switched from Research to NWS-Surveillance.

Summary of Navy Sonde Launches from Westport

Launch times:
2059 UTC Sun 07 Jan

2345 UTC Sun 07 Jan

0254 UTC Mo 08 Jan

0550 UTC Mo 08 Jan

0850 UTC Mo 08 Jan

1157 UTC Mo 08 Jan

Note: Due to a mistake in the telephone update message, two sondes were launched late in the day on Monday (0004 UTC Tues and 0307 UTC Tues), several hours after the end of the IOP. The first was successful, but the second lost all data due to the computer disk being full.


Summary of NWS Sonde Launches from Quillayute (UIL) and Salem (SLE)

Launches are generally started ~1 h before a standard 3-hourly synoptic time, so some sondes are reported as occurring 1 h before the standard synoptic hour.

 UIL Launch Times:

2000 UTC Sun 07 Jan (special)

0000 UTC Mo 08 Jan (standard)

0200 UTC Mo 08 Jan (special)

0600 UTC Mo 08 Jan (special)

SLE Launch Times:

2100 UTC Sun 07 Jan (special)

0000 UTC Mo 08 Jan (standard)

0200 UTC Mo 08 Jan (special)

0600 UTC Mo 08 Jan (special)

Note: All sondes launched as requested.