So, why wont Harvey leave Texas aloneThe problem with Harvey is that it is trapped, Phil Klotzbach, atmospheric scientist and tropical storm expert at Colorado State University, told Gizmodo in an email. Harveys unusual trajectory or lack thereof stems from the fact that its stuck between two areas of strong upper level high pressure, one in the western US, and another centered around the southeast. Hurricanes effectively move as pebbles in a stream, that is, they are steered by large scale weather patterns, Klotzbach said. The combination of these high pressure areas means that the storm is currently stationary. A tropical storm stalling out due to weak steering currents isnt so unusual in itself, but the additional circumstances surrounding Harvey have created a nightmare scenario for coastal residents. What makes this exceptional is that a its a former Category 4 hurricane, b its located very near a U. S. coastline, and c the upper level pattern is going to be very persistent, which means the stall could last for days, Henson explained via email. Harvey is trapped close enough to the Gulf that its able to siphon an endless supply of energy and moisture from exceptionally warm waters, which are also likely to have contributed to the storms rapid intensification last week. Unfortunately, some weather models are now showing that Harvey could drift back out to sea over the next few days, re intensifying a bit before hammering the coastline again. Rory Gallagher Timeline Tourdates created by Joachim Matz Maintained by John Ganjamie since 92009. If you are a teacher searching for educational material, please visit PBS LearningMedia for a wide range of free digital resources spanning preschool through 12th grade. Find the latest business news on Wall Street, jobs and the economy, the housing market, personal finance and money investments and much more on ABC News. List of well known, registered, and dynamicprivate ports. According to Klotzbach, theclosest analog may be tropical storm Allison 2. Texas and Louisiana for several days, dropping over 4. Houston. That storm, which flooded more than 7. Harvey. Events like this always cause folks to ask about the connection between hurricanes and climate change. The science is still evolving, and the answer is not simplewhile theory suggests that higher sea surface temperatures will yield more intense storms, whether were actually seeing an uptick in cyclone intensity worldwide is unclear. The trend signal has not yet had time to rise above the background variability of natural processes, according to a recent draft of the National Climate Assessment. Still, climate scientists generally agree that elevated sea surface and air temperatures play a role in intensifying storms, so it wouldnt be a shock if future attribution studies linked features of Harvey to rising temperatures. And storm surgesone of the most dangerous aspects of tropical cyclones in terms of life and propertyare being made worse by sea level rise.