Extreme Weather

At 9:26pm on Sunday April 19, 2020, NASA's GPM satellite observed an extremely vigorous convective storm cell embedded within a squall line that had produced tornadoes earlier that evening along the US Gulf Coast. NASA's GPM satellite flew over the portion of this squall line that extended over the Atlantic Ocean, 350 miles (500 kilometers) east of Florida's Coast. The Dual-Frequency Precipitation Radar (DPR) observed a storm cell whose updrafts were strong enough to lift small ice particles into the stratosphere 15.8 km above the ocean surface. Equally remarkable is that the updrafts were

Bertha was a named storm for just the briefest of periods, becoming a tropical storm on the morning of Wednesday May 27th at 8:30 am EDT just one hour before it made landfall along the South Carolina coast near Charleston. After making landfall, Bertha quickly weakened into a tropical depression and was then accelerated northward by the southerly flow between a deep trough of low pressure over the Mississippi Valley to the west and a ridge of high pressure located just off the US East Coast. Because of this, rainfall totals over the Carolina’s were not very heavy. Bertha’s biggest impact actually occurred when it was still in the formation process, before it became organized enough to be named. On Monday May 25th, a trough of low pressure became established over the Florida Straits, initiating shower and thunderstorm activity in the region. Over the next day, as this trough, which extended eastward over the warm waters of the Gulf Stream and eventually led to Bertha, slowly moved northward up the Florida peninsula, it provided a focus for showers and thunderstorms, which brought heavy rains to southeast Florida.

The 2020 Atlantic hurricane season is off to a busy start. By the first week of June, Tropical Storm Arthur had already brushed North Carolina, Tropical Storm Bertha had drenched South Carolina, and the third named storm of the year— Cristobal—was dropping torrential rain on the Yucatán Peninsula. The storm first developed in the Pacific in late May as Tropical Storm Amanda, spinning off the southern end of a seasonal low-pressure pattern called the Central American Gyre. After making landfall in Guatemala and causing deadly floods in El Salvador, Amanda weakened and became less organized as

This animation shows NASA IMERG rain rates (blue shading) and accumulations (green shading) alongside the NOAA low-pressure center track (red line) of Tropical Storm Amanda/Cristobal. The origin of this storm was in the eastern Pacific Ocean in late May 2020, where it was named Tropical Storm Amanda as it approached the southern Mexican and Central American coast. Amanda made landfall in Guatemala on May 31, where it began to deliver the first of a series of heavy rain pulses that led to flooding in the region. After temporarily stalling over land, the system reformed over the Bay of Campeche on June 1 as Tropical Storm Cristobal and made its second landfall on June 3 in Mexico. The storm continued to deliver several pulses of heavy rainfall to southern Mexico, Guatemala, and El Salvador. Some areas of the region accumulated over 60 cm (~2 feet) of rainfall throughout Cristobal's passage. The storm then crossed the Gulf of Mexico and made landfall in Louisiana on June 7 and progressed northward as a tropical depression before being classified as an extratropical low pressure system over Wisconsin on June 10. Large swaths of the U.S. Gulf Coast and Midwest as far north as Wisconsin saw accumulations in excess of 10 cm (~4 inches), and some areas along the coasts of Florida, Alabama, and Mississippi received over 20 cm (~8 inches), during Cristobal’s passage.