Friday, August 12, 2016

Louisiana Deluge

A flooding disaster of major proportions is underway in Louisiana and is likely to get worse over the next few days.

As of early Friday morning up to 15 inches of rain had accumulated during  the preceding 24 hrs. A westward moving low pressure system that is tropical in nature had been producing torrential rains from western Mississippi through eastern and  south-central Louisiana.

24-hour precipitation valid at 7:00 a.m. CDT 8/12/2016

Amounts reported by CoCoRaHS observers topped 11 inches this morning, and a late report at 7:00 p.m. tonight reported 14.65 inches (this is likely a 36 hour total).

CoCoRaHS reports >7.00 inches for Louisiana and Mississippi 8/12/2016

The U.S. Cooperative observer in Livingston, LA reported 10.55 inches of rain this morning, and then  another 6.54 inches as of 3:00 p.m. this afternoon. The observer reported rainfall rates of 3 inches  per hour for an extended period this morning. Rainfall totals exceeding 20 inches will be common by Saturday morning across Louisiana.

The low pressure system responsible for this rain has been hanging along the Gulf coast the past several days and become somewhat more organized as it drifted east. It was located over western Mississippi this morning, and slowly drifted westward during the day today.

Surface map at 1:00 p.m. CDT 8/12/2016 showing low pressure center over western Mississippi.

Visible satellite image for Louisiana at 4:15 p.m. CDT 8/12/2016. The bulging clouds over north-central Louisiana are indicative of strong convection.
 The low is expected to eventually begin drifting to the east and northeast this weekend. The potential for additional heavy rain remains high through the weekend.

Excessive rainfall outlook for the period from 7:00 a.m. CDT Saturday 8/13 to 7:00 a.m. CDT Sunday 8/14/2016.

The 3-day Quantitative Precipitation Forecast for the period from 7:00 p.m. CDT Friday, 8/12 to 7:00 p.m. CDT Monday, 8/15/2016.

Flooding is extensive. Rivers and streams rose rapidly with the high rainfall rates. Numerous rivers in southeast Louisiana and southern Mississippi were overflowing their banks and threatening widespread flooding and most rivers are expected to reach major flooding levels.

River levels and forecasts for southwest Mississippi and southwest Louisiana.
There have been two fatalities reported as a result of the flooding, and another person was reported missing at the time of this writing. Louisiana Gov. John Bel Edwards declared a state of emergency today because of the severe flooding and additional heavy rain expected.

Update Saturday, August 13  10:30 a.m.

Here are two-day rainfall totals for Louisiana. Radar rainfall estimate of 27.47" near Brownfields, LA corresponds well with observed rainfall.

48 hour rainfall totals for stations reporting >10" in Louisiana for period ending 7:00 a.m. CDT August 13.

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