Heavy Rain, Flooding Possible For Lower Mississippi Valley, Southern Plains

Persistent southeasterly winds will pump moisture from the Gulf of Mexico into the southern High Plains by Wednesday, where it will interact with an area of low pressure forming aloft over the Southwest. This will contribute to heavy rains as far west as eastern New Mexico, western Texas and western Oklahoma by Wednesday night and Thursday.This rain will then spread across the rest of Texas, Oklahoma and possibly parts of Louisiana and Arkansas by Thursday night or Friday. A separate weather disturbance moving through the southern tier of the U.S. will prolong the heavy rain threat into this weekend across those states.In addition, moisture and energy from Tropical Depression Twenty-E in the eastern Pacific could be involved in this setup. Computer forecast models are showing that after it makes landfall in Mexico as a tropical storm or hurricane, the mid-level remnants will get pulled northeastward into the south-central states by a southward dip in the jet stream over the western and central United States.

This rain is needed to help a relatively rapidly-developing flash drought, which set in over the southern Plains and Lower Mississippi Valley from mid-summer on.The heavy rain threat, while squelching the recent wildfires, may be too much of a good thing in these areas, instead triggering flash flooding. It's also possible some of the drought area may see little or no rain at all from this setup.

 A broad area of thunderstorms has been percolating near Mexico's Yucatan Peninsula the last several days. Since this weekend, the National Hurricane Center has been highlighting this area at times for a low chance of development into a tropical depression or storm over the western Caribbean Sea or the southwest Gulf of Mexico.Right now, unfavorable winds aloft are in place across the Gulf of Mexico due to the subtropical branch of the jet stream. This wind shear is a common nemesis of both developing and active tropical cyclones and has played a significant role already with several named storms this hurricane season.

Southwest Upper Low

Rainfall Outlook

Original Article: http://www.wunderground.com/news/southern-plains-gulf-moisture-heavy-rain-oct2015