Abstract

Mesoscale analysis models used in forecasting have come a long way, but there are many limitations to its accuracy, mainly due to its temporal and spatial resolution within the models. Combined with a sparse network of METARs used for surface observations and an even greater lack of upper air observations, severe weather parameters cannot be accurately measured on the mesoscale where storms are happening. Using custom built instrumentation, Operation Supercell Thunderstorm Research and Analysis (SPECTRA) closely examines the environment in the inflow region of supercells to see how the environment is influenced and how the severe weather parameters are enhanced. It is expected that moisture pooling and strongly veered winds below the mesocyclone create an environment very suitable for tornadogenesis and tornado maintenance far more extreme than what can be seen on the Numerical Weather Prediction (NWP) models. This project examines how much the environments can be enhanced, and to help find and fix biases in the mesoscale analysis.

Abstract

Wind energy is becoming a larger part of American energy production as wind farms are popping up all over the Midwest, particularly in Illinois, with large groupings of towering wind turbines. While these wind farms are forms of clean energy, they do create unintended effects to the winds around the turbines, and these effects can impact the efficiency of other wind turbines. The purpose of this research is to look at, in high resolution, the wind field around the Bishop Hill, Illinois wind farm and see its effects on the surrounding wind structure. Using the high-resolution radar on the Doppler on Wheels, the horizontal and vertical wind profile around the wind farm is analyzed using PPI and RHI scanning methods. The primary area of research is down wind of the turbines looking at the wake turbulence generated. Using the radar, downstream wind patterns were influenced by the wind turbines as well as the wind structure over the wind farm. Pockets of lesser wind velocities are seen directly correlated to the locations of wind turbines. Turbulence was also generated behind larger groupings of wind turbines. The data collected can be used to look at future placement of wind turbines to help increase their efficiency.

Severe weather is anything but uncommon in May in the United States, and 2011 was no exception.  In a particular stretch from May 22nd through May 27th, over 4,000 severe weather reports ranging from wind reports to tornado sightings came into the National Weather service as a massive storm system traversed the nation.

As tornadoes traversed the southern plains, straight-lined winds caused extensive damage across a large swath of the eastern half of the nation, and torrential rains caused significant flooding in the northeast, this outbreak went down as one of the deadliest and costliest in the nation's history.

What started as a stationary weak low-pressure center over the southern plains transformed into a powerful storm system as a deepening trough turning negatively tilted approached the plains.   As a strong jet streak rounded the base of the trough over a very well defined dry line, it sparking off a very ferocious day of storms, and this would continue as the system moved east as the trough slowly began to weaken.

This case study will be looking at the stationary low pressure sitting over Oklahoma starting on May 22th and what factors led to its strengthening and what led it to propagate eastward.  This will include the effects of the trough crossing over the low pressure, the moisture, temperature, and vorticity advection, and the approaching jet streak in the 500mb level.

Abstract

This past year, the Tri-State area (Iowa, Illinois and Missouri) saw several tornado events, as early as February and as late as December, which caused damage and injuries in several counties. Two of those tornadoes had no warning with them. Nowcasting was challenged by sub-optimal radar coverage, as well as the unique setups including an early-season QLCS tornado outbreak, overnight bowing segments with embedded supercell structures, and supercells forming on a differential-heating boundary. Despite these challenges there were no serious injuries or fatalities thanks to good forecasts leading up to the events, and the life-saving decisions those in the path of the tornadoes made.

ABSTRACT

Torrential rain, late-season flooding, warmer winter temperatures and less-extreme summertime heat. In the last several decades there has been a significant change in the annual climate in eastern Iowa and a leading suspect in the seasonal change in water content of the atmosphere. Precipitable water is one unit to measure this change. Using daily weather balloon data from Omaha, Nebraska and Davenport, Iowa, a precipitable water climatology was constructed showing a clear trend with annual values averaging two-tenths higher than five decades ago.

ABSTRACT

Since 1953 more than 2,600 tornadoes have hit the state of Iowa. Every month in the calendar year has seen at least one tornado. The most active period for tornadoes is in the late afternoon and early evening. Using records from the Storm Prediction Center and the National Weather Service a climatology was built using every report, start time and location.