IOP 6: 0000 UTC - 1500 UTC March 23
(1600 PST March 22 - 0700 PST March 23)

Report written by Vanda Grubisic, Sunday, March 29

Synoptic overview:

A moderate short wave brought WSW flow over the Sierra. The Eta model was the strongest in predicting this event with the maximum winds of 30-35 knots at 500 mb and 20 knots at 700 mb. The peak winds at 500 mb in the Eta forecast were predicted between 06 UTC March 23 and 12 UTC March 24 with the strongest cross-barrier flow at 09 UTC. The GFS and NOGAPS models were weaker with this event, with the NOGAPS being the weakest. COAMPS predicted a large amplitude wave that extended down into the valley between 06 and 09 UTC. Moisture was to be limited with this event.


The plan of operations for IOP 6 on March 23:

1. MAPR: on all the time
2. MISS: to be located at Independence airport, two radiosonde launched at 06 and 12 UTC
3. MGLASS: four radiosonde launches from Fresno at 00, 06, 09, and 12 UTC
4. Lemoore: two radiosonde launches at 00 UTC and 06 UTC


Summary of operations and observations:

The event happened earlier than predicted. This was a moderately strong wave event. The westerly momentum was mixed down in the valley and the ground network documented westerly winds in the valley during the afternoon on March 22.

A line of wave cloud cirrus formed in Owens Valley early during the day on March 22 around 1830 UTC and lasted only about an hour. More substantial wave clouds reappeared later in the afternoon around 22 UTC on the 22nd as more upper-level moisture streamed in over Owens Valley. Wave clouds with one crest immediately downwind of the Sierra, one in the middle of the valley and one over the White Range, were observed over Bishop at 00 UTC March 23. Wave clouds appeared all very high with no roll clouds underneath. A single engine pilot landing at the Bishop airport after flying in from the north at 10 kft reported moderate winds at the mountain top height, but no turbulence.

White Mountains; east of Big Pine
1227 PST

MISS was located at Independence airport, where it had been operating continuously since March 22 at 01 UTC. W to WSW were documented above 2 km, and S flow below that height between 18 UTC March 22 and 06 UTC March 23. The maximum of the WSW wind in the MISS data was 15 m/s at 20 UTC slightly above 3.5 km. After 06 UTC the winds weakened, remaining generally southerly below 1-1.5 km with some weak westerly winds in between 1.5 and 2.5 km from 06 to 12 UTC. There were strong northerly winds below 1.5 km until the end of the IOP period. Surface winds at the MISS site were westerly at 8 m/s between 0200 and 0330 UTC March 23.

There were two radiosonde launches from the MISS site at 06 and 12 UTC. The first one has no winds above 600m and a weak stable layer around 650 mb. The second has a strong inversion near the ground, and the winds are consistent with the wind profiler winds at that time.

There were four radiosonde launches from Fresno at 00, 06, 09, and 12 UTC. All show weak winds below 700 mb and strong SW to WSW winds above that. The 06, 09, and 12 UTC soundings have substantial stable layers between 600 and 700 mb.

MAPR recorded 15-20 m/s W winds between 3 and 4 km between 19 and 23 UTC on March 22 with some longer periods of positive and negative vertical velocity indicative of waves. Winds were southerly during that period below 2 km. After 02 UTC winds weaken and the MAPR signal is contaminated by the birds flying during the night.

North of Independence
1251 PST