This information is current as of Tuesday morning at midnight. When you look for a forecast, look for current information.
Terrible day today in the Southern Plains. 18 reported tornadoes. Around 100 reports of large hail. Nearly two dozen children killed at school. Thirty others dead as well.
The storms were well forecast. The area was warned. Some storms are beyond simple defenses.
Folks who live in Oklahoma hear warnings all the time. I suppose it’s easy to dismiss them and think, as has always been the case for most people, the storm will hit someone else. That was especially true because Monday’s severe weather set up in about the same place as Sunday–unusual.
Tonight concern is centered from the Missouri bootheel through Eastern Illinois and Western Indiana plus a little corner of Kentucky and Tennessee. Tuesday it will be Northeast Texas (maybe the Dallas metroplex) into Northern Louisiana and Southern Arkansas under-the-gun.
Here’s the lead from the Storm Prediction Center’s tech discussion. Read what you can. I’ll follow with a translation to English.
CURRENT INDICATIONS ARE THAT PRE-FRONTAL CONVECTION DURING THE DAY 1 OVERNIGHT HOURS WILL RESULT IN OUTFLOW BOUNDARIES LOCATED WITHIN THE WARM SECTOR AT THE START OF THE PERIOD…AND THESE ARE EXPECTED TO PROVIDE AN ADDITIONAL FOCUS FOR SUBSEQUENT THUNDERSTORM REDEVELOPMENT DURING THE DIURNAL HEATING CYCLE ON TUESDAY.
A front is moving in from the west tonight. Thunderstorms will fire up ahead of it. Cold air, outflow from the storm, will pour down from the cloudtops.
The cold air will dislodge warm parcels near the ground which will keep the thunderstorm cycle alive.
Here in Connecticut we sometimes see storms refire from outflow, but there’s little skill in predicting which exact one. That’s why most watches and warnings you get from real people (like on TV) will talk more about general conditions than saying, “If you live on Flugle Street hit the basement now.”
We can nowcast these cells, not forecast them.
Tuesday in the Lower Midwest will be muggy. Overhead the jet stream will run a moderate speed, helping to draw parcels of humid air skyward from the surface.
ALTHOUGH LOW-LEVEL WINDS WILL GENERALLY BE AOB 20-25 KT…FORECAST SOUNDINGS INDICATE WINDS WILL INCREASE AND VEER WITH HEIGHT IN RESPONSE TO THE PROGRESSIVE SHORT WAVE TROUGH…PROVIDING SUFFICIENT VERTICAL SHEAR FOR ORGANIZED CONVECTIVE STRUCTURES INCLUDING A FEW SUPERCELLS TO DEVELOP. VERY LARGE HAIL…DAMAGING WIND GUSTS…AND POSSIBLY A FEW TORNADOES WILL BE POSSIBLE…ESPECIALLY WHERE BOUNDARY INTERACTIONS MAY ENHANCE LOW LEVEL SHEAR/SRH. ACTIVITY IS EXPECTED TO GROW UPSCALE BY EVENING WITH SEVERAL QLCS/S FORMING WHICH MAY RESULT IN AN INCREASE IN WIND DAMAGE POTENTIAL. ACTIVITY IS THEN EXPECTED TO WEAKEN GRADUALLY BY 03-6Z AS THE SHORT WAVE TROUGH LIFTS NEWD AWAY FROM THE REGION AND DIURNAL COOLING BEGINS TO STABILIZE THE BOUNDARY LAYER.
There won’t be much wind on the ground, but it will increase and change direction as it climbs. Wind shear is part of the formula for supercells.
The discussion mentions QLCSs, Quasi-Linear Convective Systems. These are storms which pack a line of damaging winds on the leading edge. Maybe you heard me mention “bow echoes” on TV? That’s part of the QLCS life cycle.
The worst times for storms will be Tuesday afternoon and evening with things finally simmering down before midnight.
Tornadoes are nasty. They often pack stronger winds than the strongest hurricanes. The whole concept of safety in a tornado is more relative than absolute. Tornadoes can grow stronger than any of our prep, as happened today.
I watched a man interviewed on CNN tonight. He carried all his worldly possesions in a laundry basket. He felt terrible for those who suffered more. He considered himself lucky tonight in Oklahoma.
I just can’t imagine.