Mission Plan :

NOAA42 will conduct an NHC-tasked Reconnaissance mission and an EMC-requested TDR mission into Tropical Storm Fernand.

Mission Summary :

Completed reconnaissance Alpha pattern at 2500 ft pressure altitude with 3 legs across the center of developing TS Fernand. TDR coverage of Fernand’s circulation within 105 nm of the center using 3 Doppler analyses. All analyses were transmitted to NHC and all of the TDR data quality controlled and transmitted to NCO meeting the EMC objectives.

Very difficult to locate the center with a broad area of light and variable winds southeast of the major precipitation shield. Lowest wind and pressure were tucked up against the major convective band ending in a hook west to southwest of the circulation. There was a lot of hunting for the center on the mission but it did not affect the TDR analyses.

The TDR analyses depicted a very shallow vortex (< 2 km altitude) with 40-50 kt winds to the northwest of the center and 15-20 kt wind southeast of the center. The vortex was tilted downshear (from southeast to northwest) from 2 km to 5 km altitude by 40-50 km.

Encountered extremely heavy rain to the NW of the center with a very large stratiform rain area covering the NW semicircle of the storm. This storm will be a major rain threat over northeastern Mexico as it hits the Sierra Madre Occidental mountains.

No dropsondes were deployed as the pattern was flown at such low altitude.

Mission Problems :

MMR suffered quite a bit from severe attenuation on the legs to the northwest and downwind leg to the west of the center.

Frank Marks
6 September 2019