HOUSTON (CW39) — The storms are beginning to affect the Houston area, with some severe weather beginning to take place in some areas.

A cell of tornadoes went through from Katy to the northwest part of the Houston area, with high winds, but no details yet of heavy damage.

Meanwhile, a flash flood warning was issued for Fort Bend, Waller and Austin counties until 3 p.m.

The National Weather Service has already put most of the Houston area under a tornado watch until 6 p.m.

– The risk for severe storms has increased for potions of southeast Texas. The newest update from SPC highlights locations south of I-10, Galveston, Victoria, Angleton, Brazosport, and Bay City are just a few of the areas where our environmental conditions are becoming increasingly primed for sustaining severe storms, damaging winds, and isolated tornadoes.

As the intense upper level low crosses the state of Texas, we will see wintry precipitation occur in the north and northwestern part of the state. Temperatures throughout our atmospheric column here give Houston no chance of any snow, freezing ran, or sleet. This will largely be a wind and rain event for Houston.

Flood Threat

Simultaneously, as the cold front is approaching, a warm front will be lifting from the Gulf towards I-10. As the two boundaries collide, rainfall will quickly become wide spread across the area. The morning will have some scattered shower, but conditions will be manageable. It is along the actual frontal boundary that rain rates will begin to exceed what our roads can hold causing for flash flooding on our side streets, now even major roadways are becoming more at risk. Expect rainfall to reach 2-3″ nearly widespread, POCKETS OF 5+INCHES will occur.

Flooded roadways are nothing to mess with: while driving in flooded streets it is not possible to tell he exact depth of the flood waters.

Water only two feet deep can float away most automobiles. That may sound like a lot of water, but locations at the end of a decline CAN see that occur with the environment in place tomorrow.

Wind and Tornado Threat

There will be a notable amount of shear present at the arrival of the front, storms won’t necessarily be spawned by the heat of the day, but with the change in winds with height. This means wind where you are standing at the surface is not blowing in the same direction as the wind above. This causes a twisting motion within the wind fields, and one of the main ingredients to tornado development. A change from this morning’s update is that the conditions are MORE FAVORABLE for not only tornado development, but potentially large tornadoes. Generally we are used to EF-0s/ EF-1s being the high end of our severe impacts. Now there is a 10% or greater probability of EF2 – EF5 tornadoes within 25 miles of a point in the hatched area south of I-10.

Gusts will range from 40-60 mph. Severe thunderstorm related wind gusts could exceed that. The criteria for a severe thunderstorm warning to be issued is hail an inch or more in diameter or wind gusts over 58 miles per hour. This brings us to our next threat… HAIL.

Thunderstorms develop hail cores due to strong updrafts. The stronger the updraft, the longer the hail stone stays in the sky, collecting tiny super cooled water droplets that make it GROW!

For a full explanation on the hail making process. Check out this video below from a previous severe weather day in Houston.

Timing of Impacts

8-10 a.m. Showers begin to come widespread over southeast Texas. No pressing threat for significant winds by this time.

10 a.m. to Noon Heavy rainfall. Isolated damaging wind reports/power outages expected.

1-4 p.m. Concerning wind potential for areas south of I-10. Pockets of widespread power outages. Flash flooding threat dramatically grows. Santa Fe, League City, Beaumont… stay off roads if you can.

4-7 p.m. Coastline receives greatest wind threat, isolated tornadoes possible. Then storm push offshore.