Weather In Review And Forecast For May 17, 2015

Flood were the main problem last week. Southeast and South Texas saw a lot of rain last week. Many areas saw rain amounts of over 10 inches! The forecast models did not handle the event well. It comes to show that forecasting flood events is difficult. We have a long way to go. Here is the 7 day rainfall total.

20150518_7Day_Rainfall_Total

Many areas saw 5 to 10 inches of rain with isolated totals of over 14 inches of rain! That is a lot in 7 days! So, how wet has it been in the past 30 days?

20150518_30Day_Rainfall_Total

Many areas of Texas and Oklahoma have seen 7 to 15 inches of rain in the past 30 days. Some have seen over 22 inches! That is mostly in North Texas, Red River, and Central Oklahoma. They were dry not too long ago and now they are wet. That is a good thing as Texas and Oklahoma have been plagued by droughts. Let’s hope California gets a lot of rain as well. They need the rain as much as we do. I will gladly donate the rain to California!

So, why has it been so wet lately for Texas and Oklahoma?

20150518_500mb_GeopotentialHeightAnomaly_NH

Persistant upper level troughing over the Western US with persistant upper level ridging over the Eastern US. This type of setup is favorable for severe weather and flood events as the bring in moisture from Gulf of Mexico and Tropical Pacific. There is also El Nino.

20150518_SST_GlobalAnomaly

The area of unusually warm water in the Equatorial Pacific off the coast of South America is El Nino. It is a strong El Nino. El Nino causes the jet steam to go further south than usual. This brings in storms further south, allowing severe weather and heavy rains to fall over Texas and Oklahoma. Also, California benefits from El Nino.

Since my analog forecast from last week suggested flooding is an issue, I am going to use it again. Let’s start with the 6 to 10 day analog forecast.

20150518_6To10Day_AnalogForecast

6/12/1988-Severe weather plagues Texas in June. A F3 tornado strikes 4 miles south of Denver on 6/15.
6/2/1989-Two tornadoes in Louisiana and Florida claim 5 lives on 6/8.
6/2/1978-Heavy rain falls in the Houston area from 5/29 to 6/7. Bush Intercontinental: 12.35″; Hobby: 5.46″. Houston records its wettest 6/6 and 6/7. The rainfall total for those dates are 2.66″ and 2.29″
5/19/1963-Heavy rain falls in parts of Houston on 5/22. Houston WB: 3.10″; Hobby: 0.05″. Houston records its wettest 5/22.
6/4/1966-June 1966 Tornado Outbreak Sequence from 6/2-12. There are 57 tornadoes, which claim 18 lives. One tornado hits Topeka, Kansas on 6/8 as a powerful F5 tornado. It claims 16 lives.
6/12/1969-Tornado outbreak on 6/22. Two F4 tornadoes hit south of St. Louis claiming 6 lives in Washington County and south of Farmington. A F2 tornado hits Oxford, Nebraska claiming 1 life.
6/8/2003-2003 South Dakota Tornado Outbreak. 67 tornadoes touchdown in one day on 6/24 in South Dakota. Nebraska is hit by severe weather on 6/22. Aurora sees volleyball sized hail. A tornado to the south of Aurora claims 1 life. A total of 125 tornadoes are reported in the outbreak.
5/17/1961-Severe weather outbreak on 5/12 to 5/19 in Central and Southern US. Multiple tornadoes, strong wind, and hail reported. No fatalities are reported.
6/2/2000-Remnant of Tropical Depression 1 dumps heavy rain over Texas on 6/9 to 6/11.

Looking at the analog dates, this suggest that we could see heavy rain that could lead to flooding mixed with severe weather like tornadoes, hail, and strong winds. Let’s look into next week with the 8 to 14 day analog forecast.

20150518_8To14Day_AnalogForecast

6/4/1989-Two tornadoes in Louisiana and Florida claim 5 lives on 6/8.
6/13/1988-Severe weather plagues Texas in June. A F3 tornado strikes 4 miles south of Denver on 6/15.
6/1/1978-Heavy rain falls in the Houston area from 5/29 to 6/7. Bush Intercontinental: 12.35″; Hobby: 5.46″. Houston records its wettest 6/6 and 6/7. The rainfall total for those dates are 2.66″ and 2.29″
6/15/2004-All of Texas has a wet June. Many areas see heavy rain that leads to flooding throughout Texas. Tornado outbreak in the Panhandle on 6/21. Large hail reported of diameter of 4.25″.
5/18/1963 & 5/23/1963-Heavy rain falls in parts of Houston on 5/22. Houston WB: 3.10″; Hobby: 0.05″. Houston records its wettest 5/22.
5/17/2004-Heavy rain falls over Central Texas east of Interstate 35 on 5/13. Hearne, Texas records up to 17 inches of rain in a few hours, which leads to severe flooding. May 2004 Tornado Outbreak Sequence from 5/21-31. 389 tornadoes are reported, which claims 7 lives.
5/30/1989-Two tornadoes in Louisiana and Florida claim 5 lives on 6/8.

The 8 to 14 day analog forecast is similar to the 6 to 10 day analog forecast. Mostly heavy rain and severe weather. The June 2004 analog is interesting as Texas had a very wet June. 2004 had a developing El Nino that time. This suggests that as we head into June, it could be a wet June.

With the analog forecasts, this week will be a wet one despite what forecast models have called for recently. I do not trust forecast models when it comes to handling severe weather and heavy rain. It did not handle it well last week. One reason why I am forecasting another wet week this week. Be prepared for any flooding this week!

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