Thursday, October 31, 2013

Soggy Weather from Texas to the Great Lakes

A potent storm system traveling through the nation's midsection produced some of the heaviest rain in two months over a large swath of the central U.S. Much of this area has been dry the last two months so the rain is needed. In parts of Texas, however, it was too much of a good thing.

This storm came ashore in the Pacific Northwest on Sunday and intensified over Nevada High winds associated with this low pressure system buffeted California, Utah, Nevada, and Arizona early in the week. The winds were responsible for tipping over six tractor trailers on Interstate 580. The winds, sometimes gusting to 60 mph or higher, also damaged some buildings and caused areas of blowing dust. Blowing dust along Interstate 10 in Arizona resulted in a 19-vehicle crash that caused three deaths and a dozen injuries.

Surface weather map for Monday, October 28, 2013 at 5:00 a.m. PDT.
By Wednesday this system was moving out of the Rockies and into the Central Plains, with waves of
Surface weather map for Wednesday, October 30, 2013 at 7:00 a.m. CDT
low pressure moving along the frontal boundary. Strong southerly winds ahead of this system drew warm, moist air into the Plains and Midwest, leading to widespread showers and thunderstorms. Overnight Wednesday training thunderstorms dropped a foot of rain on parts of south-central Texas. A number of CoCoRaHS observers in Hays County, TX, just southwest of Austin, went out this morning to find out that their rain gauges had overflowed during the night. There were quite a few reports of rain around 11 inches, but some of these measurements are low because the rain gauge overflowed.  The highest amount reported was 12.45 inches in Wimberly, TX. The rain caused widespread flash flooding, as you might expect. The NWS office in Austin/San Antonio has compiled a description of this event including radar images and photos.

CoCoRaHS 24 hour rainfall amounts for Hays County, TX for the period ending the morning of October 31, 2013
Further north, two to three inches of rain fell from southeastern Kansas into northern Illinois as of Thursday morning, with three to four inch amounts in Chicago and the southern suburbs. Additional areas of showers and thunderstorms brought more rain to areas from central Illinois through Indiana during the day.

24-hour precipitation ending at 7:00 a.m. CDT Ocotber 31, 2013
Tornado watches were issued for southern Illinois, southeastern Missouri, southern Indiana, western Kentucky, and northern Tennessee Thursday night.  Two unconfirmed tornadoes were reported in southern Illinois this evening. Earlier today two tornadoes were confirmed in southwestern Louisiana.

Rain will fall in the eastern third of the U.S. the next 48 hours as the main low pressure system heads northeast into Canada and the trailing cold front sweeps to the the east coast.

48-hour Quantitative Precipitation Forecast for the period from 7:00 p.m. CDT Thursday to 7:00 p.m. CDT Saturday.

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