20180820H1 Hurricane Lane Mission Summary

Mission Plan:


The plan for this EMC-tasked mission was to fly a butterfly pattern (Fig. 1) with three passes through the center, but to first drop an AXBT at the 24-h forecast location to sample changes in the ocean as the hurricane passed.  The mission was an EMC-tasked mission.

Mission Summary:

At the mission start time, Hurricane Lane was a major hurricane with estimated maximum sustained wind of 105 kt, moving westward.  The forecast was for it to pass well south of the Big Island of Hawai'i and then turn north, with the intensity being steady-state or a slow weakening anticipated (Fig. 2).  Though no eye was visible on either the visible or infrared satellite imagery, a well-defined eye was seen on microwave imagery (Fig. 3).

The IP was reached, and an AXBT was launched, reporting a sea-surface temperature of about 27.7C, which was near what was expected.  The butterfly pattern was then completed largely as planned, and three radar analyses were transmitted.  During the mission, Lane's central pressure rose by 4 mb, suggesting that the intensity forecast was correct, at least in the short term.  Lane also was moving just south of due west during the period, which was outside the envelope of the guidance.  

The core structure of Lane was interesting.  The radar never showed a fully closed eyewall (Fig. 4), which may be why it slowly weakened.  Despite this, strong turbulence was encountered in the western 











































eyewall, where the reflectivity was quite low, during a penetration, suggesting intense building cloud tops in that region.

Radar analyses also showed the asymmetric structure, with strongest winds in the northern eyewall at all levels.  The analyses also showed very strong upper-level outflow with wind speeds > 80 kt (Figs. 5 and 6).


























Multiple AXBTs were dropped in storm.  The SST was reported to be 28.5C in the northwest eyewall, largely in front of the storm, but was also 28.4C in the southeast eyewall behind.  I was surprised at the symmetry of the SST and the lack of cooling behind the storm.

Despite being a category-3 hurricane with a slowly rising central pressure, the wind-speed reports from various instruments suggested that Lane was a healthy hurricane, at least above the surface.  One dropwindsonde reported 142 kt at about 350 m above the surface in the northwestern eyewall on the last pass, and another reported a 10-m wind speed of 137 kt at 10 m above the surface.  However, the strongest surface wind speed reported by the SFMR was only 92 kt during the flight, and the highest flight-level wind speed was only 113 kt.

Problems:

Numerous minor problems were encountered during the mission, and they were mostly mitigated by the heroid efforts of Mike Mascaro.

1.	Mike Mascaro made sure we had two radar computers and two LPS computers.  Second LPS computer died on ferry out (unknown cause).  LPS computer kept freezing through this flight and next, but only when LPS used it.  This suggests issues with the way LPS was using computer - perhaps the way their hand rests on the track pad.
2.	 With Doppler Wind Lidar scientists busy, this left two people to do LPS and radar/dropwindsonde duties.  However, because of Centos versions, two different people need to do radar and dropwindsondes.  This made the first day difficult, but by the second day, LPS sat in radar seat so drop scientists could work on drops solely.
 



























3.	 Initial data were sent out with NOAA2 NOAA2 due to flight director error.  We had to resend all dropwindsonde data, but the problem wasn’t corrected until we shut down the weather module and restarted it.
4.	 ASPEN buddy check removes far too much data in high wind speeds.  We have increased the value on subsequent flights, and suggested to AOC and the Air Force that they do the same.
5.	 There were some issues with realtime transmission of DWL data first half of flight.
6.	 Preflight downloads for DWL were slow due to tethering of computers to cell phone.  The FBO had mobile hotspots that could have worked and sped up the process.  It doesn’t hurt to ask.
7.	 Fire of unknown origin that turned out to be someone's lunch - don’t be afraid to say something if you smell something.