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For complete details on this upcoming event, watch a special version of our Daily Weather Video!

Storm Prediction Center - Day 2 Convective Outlook

Lets start out with the latest Storm Prediction Center outlook for Thursday. With their latest convective outlook issued earlier Wednesday Afternoon, they have a standard slight risk in effect for portions of West Texas and Southwest Oklahoma. While this outlook will likely change based on mesoscale features, at the time of this post, the risk extended from San Angelo, northwest to Childress, eastward to Ringgold and Eastland County.

0Z NAM: 850 millibar winds at 6 PM Thursday

We like to start off by analyzing the mid to upper levels of the atmosphere to get a general diagnosis of the amount of wind shear/vorticity that will come into play during an event. At 6 PM tomorrow, we have a positive tilt shortwave in place across the four corners region with the right-entrance region of the jet beginning to influence West Texas. In terms of wind shear, we like to see winds at or above 35 knots to support organized convection in the mid to upper levels of the atmosphere. By 6 PM tomorrow, it looks like we’ll have 50 to 70 knots of wind overspreading West Texas at 6 PM.

0Z NAM: 850 millibar winds at 9 PM Thursday

Taking a look at the low levels, specifically at 850 millibars, the 0Z NAM already has a sustained low level jet in place by 6 PM on Thursday. When determining the potential for specific severe weather hazards, we like to check the direction of the wind at 850 millibars. If the wind is coming from the southeast with 500 millibar winds from the southwest, that creates turning with height. If the winds at 850 millibars and 500 millibars are out of the southwest, that creates a linear type setup, which favors squall lines verses discrete supercells. It looks like we’ll have southeasterly 850 millibar winds tomorrow evening. At 6 PM, the NAM has the low level jet at 30 knots.

Fast forward three hours and you still have southeasterly winds at 850 millibars, but notice that instead of the 25 to 30 knots we were seeing earlier that we’re cranking up to 40 to 50 knots! That’s actually normal for a low level jet. After sunset and once the initial daytime heating subsides, the low level jet will increase. The process on why that occurs will make an excellent education post one day So, wind shear looks favorable for severe weather on Thursday across West Texas, but that’s only one of three necessary ingredients for severe weather. Lets take a look at instability…

The first thing to note from this graphic is that these instability values are for 9 PM on Thursday, nearly three hours after sunset. Even with the loss of daytime heating, instability remain high (for a cool season event) along the dryline and warm front. The warm front can be identified by the sudden drop off in instability across Oklahoma, while the dryline is your north-south feature located roughly along Interstate 27. During cool season events, I like to see instability values in excess of 1,000 joules per kilogram (J/kg). That doesn’t look like its going to be a problem tomorrow afternoon and evening. In fact, instability values appear to be in access of 1,500 joules per kilogram which is pretty impressive for early February. Now we have confirmed that wind shear and instability won’t be an issue.

0Z NAM: Surface dewpoints at 9 PM Thursday

Now for our final ingredient… Moisture! While wind shear and instability look supportive of severe weather, I’m a little concerned about instability. No doubt it will be sufficient for severe weather as any value above 50 degrees should be enough for severe thunderstorms, I’m looking in terms of the hazard of more significant severe weather, like tornadoes. For surface based thunderstorms capable of producing tornadoes, I generally like to see dewpoint values in excess of 60 degrees. During the spring time, that number increases to 65 degrees. Yet, there are a few factors that may help thunderstorms tomorrow develop low level rotation even with the lower dewpoint values. The first factor is the terrain and elevation. If thunderstorms form on the caprock, the higher elevation may allow thunderstorms to produce organized low level rotation with dewpoint values in excess of 55° verses the 60° dewpoint values I look for. The second factor is that surface temperatures won’t get too warm, likely upper 60s to lower 70s. That means we won’t have a large temperature/dewpoint spread which will keep cloud bases lower. The third factor is that storms may remain surface based well into the evening, when they will be able to use the abundant wind shear in place. We’ll find that out tomorrow…

Either way, it does appear we will see a complex of thunderstorms form across the eastern Texas Panhandle and Northwest Texas between 5 and 9 PM Thursday, before moving northeast into Oklahoma. The primary hazards with a squall line would be damaging winds and the possibility of large hail. In discrete thunderstorms, large hail and the possibility of a tornado would be possible. If we end up with higher moisture values then currently anticipated, the tornado threat would increase substantially. See the video for complete details…

Storm Prediction Center - Day 3 Convective Outlook

0Z NAM: Instability at 3 PM Friday

The severe weather threat will spread east to the Interstate 35 corridor on Friday as the upper level storm system begins to push northeastward. Compared to Thursday, instability values appear to be much lower. In fact, the NAM doesn’t have any instability values over 500 J/Kg across North Texas on Friday. While instability levels will be higher across South Texas, the upper level storm system will be too far north to cause any issues that far south. There may be a few severe wind reports as the squall line passes across North Texas on Friday, but at this point the severe weather threat looks fairly marginal. We’ll keep an eye on it though and provide an update with our February 2nd Daily Weather Video.

I am planning to chase in West Texas on Thursday. My laptop is still down for repairs so I’ll have to put my desktop in the car as the backup computer. I’m not sure if it has the processor power to stream live video, but if it does I’ll certainly have that available on Thursday! Stay tuned for the latest updates on our Facebook and Twitter pages. I hope to have our next weather video posted by 9:30 AM on Thursday.