Pacific Tropical System Injects More Moisture into U.S.

It has been an active tropical weather season in the eastern Pacific.  As of today there have been 18 named storms, with 13 of those reaching hurricane strength. The eastern Pacific season is above normal so far this year. At this point in the season the average number of named storms is 13 and hurricanes seven.

The increase in storms has been a "good news, bad news" situation for the southwestern U.S. It has been good because there has been significant improvement in (but not elimination of) drought conditions in much of New Mexico, the southern half of Arizona, and western Texas since early July. The bad aspect is the amount of flooding and flash flooding that has occurred as a result of heavy rains from the enhanced moisture.

As of noon Tuesday Simon was a minimal tropical storm located just off the central coast of the Baja California peninsula, and by evening Simon was downgraded to a tropical depression. Over the next few days moisture associated with Simon will cross through the Desert Southwest and then eastward across the country.

Quantitative precipitation forecast for the 72-hour period ending 7:00 p.m. CDT on Friday, October 10.

 
A large high pressure system over the upper Midwest will keep most of the precipitation associated with this moisture in the southern half of the country. A wave of low pressure moving across the frontal boundary dividing cool dry air to the north from the warmer, moist air to the south will provide the trigger for widespread and potentially heavy rain. Heavy rain is expected across Arizona - again - , and presenting a threat for flash flooding the next couple of days. The threat for heavy rain will then shift to the Central Plains and Midwest.

Surface weather map forecast for 7:00 p.m. CDT Wednesday, October 8.

Surface weather map forecast for 7:00 p.m. CDT Thursday, October9

Unfortunately very little, if any of that rain will reach parched California, where severe to exceptional drought encompasses 83 percent of the state.

Status of California drought as of September 30.

The rain through southern southern half of the U.S. will slow up fall harvest which has been progressing very nicely with the long stretch of dry weather at the end of September.