Report written by Vanda Grubisic, Tuesday, March 30
Synoptic overview:
With the Pacific low located off the coast of British Columbia and Washington, flow at 500 mb was W to SW of moderate strength (30-35 knots) with winds at 700 mb light and not very well organized. As predicted by GFS, the wind speed at 500 mb was to achieve a peak of 45 knots at 18 UTC March 24. COAMPS predicted strong wave activity developing in central Owens Valley by 06 UTC March 24 and reaching a maximum in amplitude at 09-12 UTC March 24, with the 308 K isentrope reaching down to 2 km on the lee slope. This IOP was driven by the verification of the COAMPS forecast for strong wave activity under these conditions.
The plan of operations for IOP 7 on March 24:
1. MAPR: on all the time
2. MISS: to be located at Independence airport, one radiosonde launch at 12 UTC
3. MGLASS: three radiosonde launches from Fresno at 06 UTC, 12 UTC, and 18 UTC
4. Lemoore: no activity
Summary of operations and observations:
The strong wave event predicted by COAMPS did not occur. Westerly winds were not observed at or near the ground during this IOP at either MISS or MAPR site nor at the stations of the ground network.
MISS was located at Independence airport. During this IOP, winds below 1-1.5 km underwent a regular turn from southerly during the day (afternoon/evening) to northerly during the night. Similar low-level winds were observed at the MAPS site as well. At the beginning of the IOP period, weak easterly winds were documented by MISS between 2 and 3 km, turning to weak NW above 3 km. Perhaps a signature of an elevated rotor? After 10 UTC, W winds were observed to reach down to 1.5 km and increase in strength to a maximum of 10 m/s during this IOP.
Besides an inversion near the ground, the temperature profile from the MISS radiosonde launch does not show many features. Winds were weak NW below the mountain-top height, then W and SW further aloft.
The first MGLASS sounding (06 UTC) shows a stable layer between 700 and 800 mb and W winds throughout. The 12 UTC sounding shows a stable layer between 650 and 700 mb, and the wind profiles similar to the one obtained at the MISS site.