Hurricane Earl drew in the researchers from the CAMEX and TEFLUN teams even as the storm was driving away the last tourists of summer.

Four aircraft probed and measured the weather ahead of Earl on Wednesday as it grew from a Category 1 to Category 2 hurricane and crossed the Gulf Shores into the Florida panhandle.

NASA's ER-2 and DC-8 and the University of North Dakota's Citation took off at 2 p.m. EDT to sample the rainfall intensities right before landfall. This storm, which was very disorganized, was upgraded from a tropical storm to a Category 1 hurricane status just a few hours before takeoff. By landing time Earl had been upgrade to a Category 2 hurricane.

In collaboration with NOAA, researchers from the University of Alabama in Huntsville researchers were positioned at the Tallahassee Airport to collect wind profile and surface observations while Texas Tech University investigators collected high resolution wind tower measurements just west of Panama City. Although the UAH team is not a part of the CAMEX-3 campaign, their data will complement the airborne studies of Earl.

Right: A color image from the NOAA-12 weather satellite's Advanced Very-High Resolution Radiometer shows Hurricane Earl as it moves across the Southeastern United States today at 6:58 a.m. (1158 UT). This image was produced by the Ocean Remote Sensing Group at The Johns Hopkins University's Applied Physics Laboratory. (Links to

The aircraft are being used by a national team of scientists in the Convection and Moisture Experiment (CAMEX-3) to study hurricane growth, and the Texas and Florida Underflight (TEFLUN) experiment to validate measurements by the Tropical Rainfall Measuring Mission (TRMM). The experiment team comprises researchers from NASA, the National Oceanic and Atmospheric Administration, and universities.

Several flights have served the needs of both campaigns. The CAMEX team had a phenomenally successful series of flights studying Hurricanes Bonnie, Danielle and, now, Earl.

On Wednesday's flights, the aircraft were set up on north-south lines in the Gulf of Mexico between Tampa and Tallahassee, Fla. Light rain was observed on these lines.

Next, the line was shifted west toward Tallahassee. Moderate to heavy rainfall was observed on this line. A NOAA WP-3D Orion aircraft passed through the area to study the wind field and storm surge conditions of the landfalling hurricane. The Hurricane Hunters of the USAF 53rd Weather Reconnaissance Squadron also flew through Earl Wednesday to monitor its wind speeds, barometric pressure and eye location

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After flying along these additional north-south lines, the aircraft shifted back to the original line to sample more rainfall. After these maneuvers were completed, then the DC-8 was asked to perform a spiraling maneuver down to 14,000 ft to sample the microphysics of the rain and to perform a passive microwave study of the rain at various heights. The DC-8 then returned to Patrick AFB, Fla., the CAMEX staging area, to complete a 6-hour mission. The ER-2 landed approximately 30 minutes later.

Thursday was a "no fly day" for the DC-8 and ER-2.

Hurricane Earl continues to be the major player in today's forecast for east central Florida, according to CAMEX forecaster Jeff Halverson. Earl has assumed a largely extratropical character with a pronounced synoptic-scale dry intrusion entering from the west-southwest, rain skewed largely to the northeast of center, lack of a well-defined center or eye, and a pronounced convective rain band draped from northeast to southwest over central Florida.

For the next two days, the outlook will be for widespread thunderstorms to continue. If Earl tracks to the north, the large-scale convergence over the peninsula should relax and allow the sea breezes to assume a greater degree of influence. Dry air aloft could still enhance the potential for locally strong downdrafts in some of the cells.

And over the next several days, the models track Earl northeastward along the Eastern Seaboard. A new area of convective activity, located over the central Caribbean, shows some signs of consolidation and could become a tropical depression within 24 hours. The feature is drifting west at about 15 mph. We'll have to watch this for the possibility of a Francis in the near future.

CAMEX-3 - the third Convection and Moisture Experiment - is an interagency project to measure hurricane dynamics at high altitude, a method never employed before over Atlantic storms. From this, scientists hope to understand better how hurricanes are powered and to improve the tools they use to predict hurricane intensity.

An overview story (Aug. 12, 1998) describes the program in detail. The study is part of NASA's Earth Science enterprise to better understand the total Earth system and the effects of natural and human-induced changes on the global environment. A midterm story (Aug. 31, 1998) reviews the first month of operations and the windfall of data.

Measuring distance and speed

Because meteorology and aeronautics first used modified nautical charts, their data bases are in nautical miles and knots (nautical miles per hour). In these stories, we use Standard International ("metric") units first, and give more familiar measurements in English units and the original measurements in nautical units. Because of rounding and because the wind speeds originally are expressed in knots, km/h speeds to knots may be slightly different from the numbers in the story.

km - kilometer (1 km = 0.62 smi = 0.54 nmi) 

km/h - kilometers per hour 

mi, or smi - miles (statute miles; 1 smi = 0.87 nmi = 1.61 km)
mph - (statute) miles per hour 

nmi - nautical miles (1 nmi = 1.15 smi= 1.85 km) 

kts - knots (nautical miles per hour) 

 

Standard International Units: 

English (or US) units: 

Nautical units: