After an extraordinary swing from drought to deadly flooding, the last thing the southern Plains need now is more heavy rain. But that's exactly what it got on Thursday night into Friday morning, as another massive area of thunderstorms congealed late Thursday and rumbled slowly across the Lone Star State.
So far this month, enough rain has fallen to cover the entire state of Texas in 8 inches of water. This translates to 35 trillion gallons, according to the National Weather Service in Fort Worth.
In Lubbock, Texas, the three to six inches of rainfall that fell on Thursday evening pushed the monthly total well past record territory and caused widespread, dangerous flash flooding.
Some of the most disruptive impacts have been in Dallas, where officials once again had to close a north-to-south runway at Dallas-Fort Worth International Airport, one of the world's busiest, because a sinkhole that had been under repair after earlier rains re-opened amid the new torrential downpours.
The Dallas area picked up between three and seven inches of rainfall overnight, according to the National Weather Service, leading to dozens of high water rescues and impassable roadways.
The disruption in Dallas was not as severe as what occurred in Houston earlier this week, when five people died of flash flood-related causes, but parts of the city were virtually paralyzed during the early morning hours. The sinkhole reportedly measures 25 feet by 25 feet, and poses a hazard to aircraft.
Because of the added rains, Dallas set a record for the wettest May in that city's history, with 16.07 inches through 6 a.m. CDT on Friday. This beat the old record of 13.66 inches, which was set in 1982. This record may be added to through Sunday, when more heavy rainfall is in the forecast before conditions dry out starting early next week.
Loop 12 and I-30 in Dallas -- flooded pic.twitter.com/gA3yIy7FYB— Jason Allen (@CBS11JasonAllen) May 29, 2015
JUST IN: @dfwairport: Overnight rains damaged the drainage line being repaired near runway 18-L. That runway is now closed. #CBS11Wx— CBSDFW (@CBSDFW) May 29, 2015
Red River at I-35 crossing north of Gainesville, now at major flood stage, 35.22 ft., a Top 5 historic crest— Jason Allen (@CBS11JasonAllen) May 29, 2015
The additional rainfall served to add exclamation points to some of the rainfall records in Texas and Oklahoma. Texas has had its wettest May on record statewide, based on average rainfall totals across the state. The state has averaged at least 7.54 inches of rain and rising, besting the previous record of 6.66 inches in June of 2004, according to the Texas state climatologist's office.
The flooding has killed at least 23 people across Texas and Oklahoma, with the heaviest toll in the Hill Country town of Wimberley, Texas, where a flash flood washed homes away on Saturday night into Sunday morning.
When the final tallies are released, it is likely that this May will rank as one of the wettest months of any month on record in some locations, as it already does across the state line in Oklahoma City.
Wichita Falls, Texas has had nearly 17 inches of rain so far this month, while Oklahoma City is pushing closer to 20 inches. This is more rain than these locations recorded during the entire year last year, when Texas and Oklahoma were still in the throes of a severe four-year-long drought.
Lubbock, Texas, where more flash flooding occurred on Thursday, has now had nearly a foot of rain for the month, which is about 10 inches above average for the month.
The National Weather Service (NWS) issued a forecast discussion on Friday morning warning of heavy rainfall on Friday in southeastern Texas, potentially including the Houston area, along with eastern Oklahoma. "THIS AREA COULD EASILY SEE SEVERAL INCHES OF RAIN PER HOUR," the NWS said regarding southeast Texas in particular.
There has been enough rain across #Texas during May to cover the entire state nearly 8 inches deep. That's over 35 trillion gallons! #txwx— NWS Fort Worth (@NWSFortWorth) May 29, 2015
A photo posted by westtxjay (@westtxjay) on May 29, 2015 at 2:53am PDT
Officers of @DallasPD are working to safely move cars and people from high water throughout #Dallas. #DFWTraffic pic.twitter.com/TJvCCjPj1M— Colton Johnson (@JohnsonDPD) May 29, 2015
The torrential rains are linked to an incipient El Niño event in the tropical Pacific Ocean, which is causing a moist airflow to funnel northward from the Gulf of Mexico all the way to the Dakotas. When this moisture encounters atmospheric disturbances that encourage the air to rise, clouds and precipitation are the result.
Long-term trends across the U.S. clearly show that heavy precipitation events are becoming more common as the climate warms, largely because warmer temperatures allow more water vapor to be added to the air. This gives storms an added dose of power, akin to giving a baseball player steroids and watching them hit more home runs over time.
Hotter planet increases drought in dry places (increased evaporation) and floods in wet places (more water in air means heavier precip) 1/2— Scott A Mandia (@AGW_Prof) May 29, 2015
John Nielsen-Gammon, the Texas state climatologist, told the Texas Tribune that precipitation in Texas has increased by 7 to 10% during the past century, while the frequency of 48-hour heavy rainfall events have become almost twice as common in the same period.
Climate science research also shows that warming temperatures also makes the opposite end of the precipitation extreme spectrum more severe, as Nielsen-Gammon found when analyzing the severity of the Texas drought.