For this year that phenomena started in February and intensified during March and April with very few rain producing weather systems. By the later part of spring and early summer the La Niña phenomena weakened and became a non player, however the very dry soil over the Texas region intensified the drought and allowed a semi-permanent upper-level high pressure to build over the area keeping most of the rain bearing tropical disturbances either south or east of the Texas Gulf Coast. As a result, most of Texas was left high and dry resulting in the current 20-25 inch rain deficit we are currently experiencing in the Houston area and the increased fire danger as wildfires quickly spread across central and east Texas.
Unfortunately the main players that caused the very intense drought last winter are coming back this winter in the form of another potential La Niña condition. We currently are favoring a redeveloping moderate to strong La Niña this winter based largely on another weather phenomena called the Pacific Decadal Oscillation, or PDO. The PDO is a large scale weather cycle over the northern Pacific Ocean which demonstrates alternating periods of cold and warm cycles, which can typically last 10 to 20 years. When the PDO is in its cold phase La Niñas typically are more frequent and intense while the reverse is true during the warm phase of the PDO. For this year the PDO has shifted toward the negative phase, which is signaling a redeveloping La Niña later this fall as colder than normal water over the eastern Pacific Ocean is funneled southward into the eastern Tropical Pacific.
As a result, we should see the current drought persist through next spring over most of Texas, including the greater Houston area as La Niña intensifies. Yes, Texas will likely see some welcomed wet periods at times during the fall and early winter as the polar storm track occasionally shifts south bringing quick bursts of precipitation associated with cold fronts and other fast moving disturbances; however, below to well-below-normal precipitation will likely by the dominant weather trend over most of the state though next May.We can always hope for some type of a weak tropical system during the latter half of September into October, but even that scenario is looking less likely with time.