Articles

At the time of the Global Precipitation Measurement (GPM) Core Observatory overpass (April 1, 2017, 0550 UTC), the storm's center of low pressure was south of Long Island. At the mid-levels of the atmosphere, the circulation was centered over northeast Pennsylvania. This led to a classic overrunning, warm conveyor setup, which happened when the counterclockwise low level flow drew in cold air out of the north/northeast (hence "Nor'easter") from Canada. Higher up, warm and moist air from further south was lifted over this cold air and resulted in precipitation in the form of snow at the surface...

Tropical cyclone Debbie formed in the Coral Sea northeast of Australia om March 24, 2017. Debbie intensified and had hurricane force wind speeds within a day of formation. While headed toward northeastern Australia Debbie reached it's maximum sustained wind speeds estimated at over 100 kts (115 mph) on March 27, 2017 (UTC). Tropical cyclone Debbie came ashore on March 28th and brought destructive winds and extremely heavy rain to northeastern Australia. It was reported that heavy rainfall caused flash flooding that cut off a coastal town and covered several roads in Queensland. The GPM...

The West Coast is once again feeling the effects of the "Pineapple Express". Back in early January one of these "atmospheric river" events, which taps into tropical moisture from as far away as the Hawaiian Islands, brought heavy rains from Washington and Oregon all the way down to southern California. This second time around, many of those same areas were hit again. The current rains are a result of 3 separate surges of moisture impacting the the West Coast. The first such surge in this current event began impacting the Pacific coastal regions of Washington, Oregon, and northern California on...

After more than four years of drought, Californians may wonder where the current rain is coming from. Using satellites, NASA scientists have a unique view of the sources of precipitation, and how it reaches the western United States. Rain is often carried by narrow tendrils of moisture called atmospheric rivers that occur all over the world, shown here in white. The atmospheric rivers that affect the western United States are known as the Pineapple Express because they transport water vapor from as far south as Hawaii to California. When the moisture reaches land, it is forced up over the...