Mission Plan:
Primary Mission : Langrangian Alternate Mission: Sunrise photochemistry in clear air Future Mission(s): Continuation of up to three more flights on the Lagrangian mission, possibly extending through 1130 UTC Saturday 2 December ( 2230 LDT, 2 Dec).Aircraft Operations
Take-off Time: Flight #18. 0230 LDT, Friday 1 Dec (1530 UTC, 30 N0v.) Flight #19. 1330 LDT, Friday 1 Dec (0230 UTC, 1 Dec) Flight #20. 0230 LDT, Saturday 2 Dec (1530 UTC, 1 Dec) Flight #21. 1330 LDT, Saturday 2 Dec (0230 UTC, 2 Dec) Alternate mission, same as Flight #18. Pre-flight Weather Briefing Time: Flight #18. 0030 LDT, Friday 1 Dec (1330 UTC, 30 Nov) Flight #19. 1130 LDT, Friday 1 Dec (0030 UTC, 1 Dec) Flight #20, 0030 LDT, Saturday 2 Dec (1330 UTC, 1 Dec) Flight #21, 1130 LDT, Saturday 2 Dec (0030 UTC, 2 Dec) Alternate mission, same as Flight #18. Updates: Lagrangian decision update 2030 LDT, 30 Nov (0930 UTC, 30 Nov) Updates on positions for Discoverer and Southern Surveyor will be transmitted at approximately 2100 LDT (1000 UTC). Update on balloon launch numbers and times will be made at Pre-flight weather briefing (0030 LDT, 1 Dec). Airborne Mission Scientist: Flight #18, Lenschow Flight #19, Huebert Flight #20, Lenschow Flight #21, Huebert Mission Scientist: Flight #18, Huebert Flight #19, Lenschow Flight #20, Huebert Flight #21, LenschowShip Operations
Discoverer: Discoverer located at 44 55'S 141 09'E this evening. It will be in the vicinity of 46S 143S by approx 1030 UTC this evening. ISS soundings continue every 6 hours. Three hourly launches in support of the Lagrangian mission will be begin at 0900 UTC this evening. See catalog reference below for detailed instrument status. Discoverer Lead Scientist: Tim Bates Southern Surveyor: Southern Surveyor position at 0600 UTC 30/11 is at station trans-P4 50S 145.5E. Soundings continue every 12 hours. See catalog reference below for detailed instrument status. Southern Surveyor Lead Scientist: Bronte Tilbrook
48 hour MSL P Prognosis is here
72 hour MSL P Prognosis is here
Latest Visible Sat Picture is here
Surface Wind 24-h forecast is here
GASP trajectory analysis is here
Synoptic Situaton at 00Z Thursday 30/11/95:
Developing front lies along line 33S 130E/40S 139E/42S 140E/46S 150E/50S 156E moving SE at 20/25 knots in the north grading to easterly at 30 knots south of about 46S. The front is forecast to move over Tasmania during the evening and develop a small low near 47S 155E at 00z tomorrow, with a front extending back to about 38S 150E.
A deep low central pressure about 970 hPa near 55S 138E moving SSE at about 10 knots, forecast to be near 558S 139E at 12z tonight and south of 60S near 150E at 12z tomorrow night.
The broad NW/SW stream around the low near 55S 138E persists over the ACE area, however the developing front near TAS is likely to interrupt this somewhat this evening.
The next cold front is near 40S 110E/45S 113E/50S 112E moving E at 35 knots, forecast to be near 41S 130E/45S 136E/50S 137E to a 978 hPa low near 54S 130E at 00z tomorrow. Front likely to move through the 145E area at approximately 12z tomorrow night whilst weakening and slowing down.
Prognoses: 0-24 hours: The progs are now reasonably in agreement with regards to the movement and development of the front about to move through Tasmania. Whereas yesterday, the EC prog developed a 996 hPa low on the west coast of Tas for 12z tonight, the latest run of the progs are all placing a trough over the area, but no closed low. In view of the latest satpics, this looks reasonable. Some development is taking place on the developing front, however a closed low is not likely to form until it moves off to the southeast of the state at about 25 knots, under the influence of a strong W/NW jet stream. Some weak ridging is likely to develop in the wake of the front and it is in this that the balloons are planned to be launched for the start of the Lagrangian experiment early tomorrow.
24-72 hours: The progs weaken the front east of 160E and the stream is likely to tend more northwesterly under the influence of the down stream ridge, located east of NZ. In the meantime, the front moving into the western parts of the ACE area tomorrow will weaken as it passes Tasmania's longitudes, with the cold front and associated low following that on Saturday looking a much more significant complex as it moves into 130E on Saturday night.
FORECASTS FOR TONIGHT AND FRIDAY:
Cape Grim: Weather: Showers and the chance of a thunderstorm this evening. Showers easing overnight and mostly clearing tomorrow morning. Wind: West to northwest winds 10/20 knots turning west to southwesterly overnight and easing to 10/15 knots. Winds possibly returning to the northwest late tomorrow.
Macquarie Island: Weather: Occasional showers but fine most of the time until tomorrow evening when showers increase. Wind: Chiefly northwest winds 15/25 knots increasing to 20/30 knots later tomorrow.
R/V Discoverer Weather: A few light showers tending to ease overnight and mostly clear tomorrow as you move eastwards. Wind: Northwest winds 15/25 knots, possibly increasing to 30 knots if you are still west of 145E after 06z tomorrow. 2 to 3 metre seas. West to northwest swell 3 to 4 metres slowly decreasing.
R/V Southern Surveyor Weather: Showers, easing for a period overnight and early tomorrow, increasing again during the afternoon and evening. Wind: Northwest winds 25/30 knots, possibly reaching 35 knots at times tonight and again tomorrow night. 3 to 4 metre seas. 4 to 5 metre west to northwest swell decreasing slightly tomorrow.
REVIEW OF PREVIOUS DAY's FORECASTS:
The low progged by the EC to develop off Tas' west coast has not yet eventuated and thus the GASP/US and UK progs were correct. This means that the southerly change predicted for the Discoverer will not eventuate tonight, and winds will stay west/nw'ly. Other than that, the forecasts have held together quite well, with the Southern Surveyor experiencing gale force winds and large seas and swells last night. Weather at all the platforms looks to have been much as forecast.
Reporter: Barry Huebert
We are hoping to start a Lagrangian experiment at 0230 local tomorrow morning. A weak disturbance is passing through Hobart tonight, and we will try to place 1 or 2 balloons in it. Since the system is slowing down, we may actually be able to get in four flights, depending on how the trajectories evolve. There was considerable uncertainty this morning about the amount of clear air behind the disturbance, but the latest pictures show wide clear spaces with occasional (suppressed) cumulus, so it should be an excellent case to follow.
Since the first two flight should have at least 6 (maybe even 7) hours on station, we plan to fly two complete sets of five 30 minute Lenschow circles (4 in BL, 1 just above) and repeat at least one circle (probably around 500' altitude) a third time. To get the maximum time-change on each flight, we may start and end with 500' legs. This altitude is convenient because it is the lowest altitude the C-130 can fly at night.
Our current plan (in UTC) is as follows:
***Thursday local:
0930 Meet at airport, with latest trajectories from Siems and Businger and
high resolution satellite image from Durkee, to decide on the final
position to start the experiment. Disco could still relocate by as much
as 60 nmi before the nominal balloon launch time.
1000 Advise Disco on possible change of location and timing of launch.
***Friday local:
1330 A. Weather brief and power on the C-130.
B. Examine the last (1115) high resolution satellite image for clear
spaces.
C. Begin filling the first balloon on Disco, if it looks like a 1550
launch of two balloons is advisable.
1400 A. Examine latest ECMWF trajectories from Businger, and advise Disco on
launch times.
B. Disco powers down engines as much as possible.
1430 Begin preparing second balloon
1530 A. Launch both balloons from Disco, within 15 minutes of each other
B. C-130 T/O from Hobart, flight #18
1630 C-130 on station with balloons
1730-1800 A. Twilight and sunrise on location
B. Disco powers up engines and begins chasing balloons
(but slowly enough that it never catches them).
Any of the following could terminate the Lagrangian sequence:
1. We have lost contact with the balloons.
2. The balloons have moved so far from Hobart that we cannot achieve
at least 2 1/2 hours on station.
3. Precipitation or convection has destroyed the continuity of
the boundary layer.
That's where we stand as of 5 PM local time. Updates will be sent
according to the schedule above.