Fresh off of Wednesday’s calamity in Oklahoma City involving supercells and tigers, the region is preparing for another two full days under the threat of a significant, multi-day tornado outbreak. Some of the tornadoes that form on Friday and Saturday could be intense and long-lived, accompanied by hail larger than baseballs and destructive wind gusts.
A series of supercells parked themselves over the Oklahoma City metropolitan area during the late afternoon and evening hours on Wednesday, producing several tornadoes (some of which were intense), large hail, and overwhelming amounts of rainfall.
The city’s airport broke its all-time one-day rainfall record for the month of May, and recorded its third-highest one-day rainfall total since records began in 1948. Will Rogers World Airport recorded 7.10 inches of rain yesterday, most of which fell over the span of about six hours. (The record for highest one-day rainfall total in Oklahoma City is 7.62” set back on June 14, 2010.)
OMG....I have never seen this happen to a tornado shelter. We told you this rainfall in OKC was historic pic.twitter.com/cRqRZShniDMay 7, 2015
The rainfall caused significant flash flooding across the region, prompting the National Weather Service to issue a rare “flash flood emergency,” which is a step above a flash flood warning and indicates the serious and unprecedented nature of the flooding. The rain fell so hard and so fast that a couple of in-ground tornado shelters floated to the surface, painting a surreal and dangerous picture, given the other threat that day.
Unfortunately, one person drowned when floodwaters filled up the tornado shelter in which she took cover from the storms. Despite these several incidents with tornado shelters yesterday, tornado shelters that are reinforced and rated (both above-ground or below-ground) represent your best chance for survival during a tornado.
Speaking of which, several tornadoes also touched down across the region, also prompting the NWS to issue an equally-rare “tornado emergency” for Bridge Creek and Newcastle, south of Oklahoma City and in that vulnerable I-44 corridor that can’t seem to catch a break from bad tornadoes. The tornado that hit Bridge Creek has a preliminary EF-2 rating from NWS Norman, while the one that hit the west side of Norman is preliminarily rated EF-1.
Numerous people were injured in yesterday’s tornadoes, including several residents of a mobile home community near Valley Brook, Oklahoma, where a particularly ugly rotation blew up on radar and sat over the area for more than five minutes. The associated radar image is pictured above—view on the left shows winds in the storm (green moving east, red moving west), while the view on the right shows the correlation coefficient; the large blue ball that develops north of Valley Brook is debris being lofted into the atmosphere. This tornado was also given a preliminary EF-2 rating.
Oh, and damage from the storms allowed several tigers to escape from the Tiger Safari in Tuttle, which is southwest of OKC near Bridge Creek. Authorities managed to round up all of the animals without incident.
Outbreaks on Friday and Saturday
Weather models are consistently showing all of the ingredients necessary for a raucous severe weather outbreak taking shape on both Friday and Saturday, with western Oklahoma the target on both days. The Storm Prediction Center has taken the relatively rare step of issuing a moderate risk for severe weather—a four on a scale from zero to five—for both days. They usually wait until the day before (or the day of) the outbreak to issue moderate/high risks.
The main threat from the thunderstorms on both days will be tornadoes—some of which could be intense and long-lived—very large hail the size of baseballs or larger, and destructive wind gusts. It’s important to keep in mind that these risk areas aren’t set in stone. The greatest risk for widespread severe thunderstorms lies within the moderate risk area, but don’t ignore the enhanced, slight, and marginal risks, either. Without naming any event in particular, some damaging tornadoes over the past decade or so have occurred in slight risk zones or near the edge of a moderate risk.
Here’s what the threat looks like right now for Friday—the next update from the SPC will roll out after midnight Eastern Time:
But it’s Saturday that has even seasoned meteorologists concerned.
In the lengthy discussion written by the Storm Prediction Center to explain/justify their forecast, they include the following tidbit:
[EVIDENCE SUPPORTS] A RELATIVELY HIGH CONFIDENCE FORECAST OF NUMEROUS INTENSE STORMS/SUPERCELLS CAPABLE OF PRODUCING VERY LARGE/DAMAGING HAIL AND A FEW STRONG/LONGER-LIVED TORNADOES IN THE MODERATE RISK AREA.
If you live in any area at risk for severe weather over the next couple of days, make sure you have multiple ways to receive severe thunderstorm and tornado watches/warnings. Never rely on tornado sirens as your only warning for severe weather. Make sure you have a plan in place to take quick action, especially if a tornado threatens your location. If you know tornadoes are on the horizon, stay as close to a safe spot as possible, taking great care to avoid getting caught on a road or in a big box store during a tornado warning.
[Images: AP, Gibson Ridge, author]