Continuing the trend of the past few days, strong storms are set to fire up again today across portions of the Southern Plains into the lower Mississippi Valley. The Storm Prediction Center has even issued a moderate risk for portions of central Oklahoma, southern Kansas, and a very small portion of Texas.
The main risks today will yet again be large hail and damaging winds with a 45% chance of severe hail and severe wind within 25 miles of a point being predicted by the SPC within the moderate risk area. An additional 10% or greater chance of wind gusts 65 knots or greater and hail two inches in diameter or greater exists within the moderate risk area as well. The storms will pack a punch this afternoon and evening once they are able to break the cap that will be in place this morning and in the early afternoon. However, once storms are able to do this, they will have large amounts of CAPE, allowing them to grow rapidly, producing strong updrafts. These strong updrafts coupled with steep mid level lapse rates will allow for large hail to be a concern again today. Below is CAPE as modeled by the 15Z run of the RAP. A large area of CAPE in excess of 3000 J/kg is expected to exist by the model over most of the western region of the SPC’s moderate risk.
Not only will large hail and damaging winds cause issues today, but a few tornadoes could be possible also. The SPC has highlighted some areas of north central Oklahoma as well as south central Kansas in a 10% chance of tornadoes within 25 miles of a point. An even larger area of 5% exists beyond this covering all of the moderate risk area as well as some of the slight risk area for today.
However, taking into account the hodographs produced by the 15Z run of the RAP, I believe the tornado threat may be limited to just a few short lived tornadoes. Most of the hodographs produced by the RAP exhibit a fairly unidirectional wind profile meaning storms will either split often, resulting in short lived tornadoes, or form into bowing lines of storms leading to enhanced wind damage threats. A few hodographs within this 10% region do show great turning at the lower levels but quickly becomes more unidirectional at the upper levels. Below is one of the better hodographs I found from central Oklahoma during the evening hours. If hodographs like this occur this evening, a couple tornadoes could become longer tracked but like yesterday, I believe storms forming into lines of storms will limit this threat.
Taking a look at the wind profile at a few different levels now, you can see some of the issues with it. Below is the 15Z run of the RAP depicting surface dewpoints and wind, 850 mb winds, and 250 mb winds this evening.
Surface dewpoints will be well into the 60s with some areas even seeing readings at or just above 70 degrees Fahrenheit. Surface winds will be out of the south across the area allowing for warm and moist air to advect into the region. The best winds may exist across Oklahoma, especially towards the southern half of the state where they are forecasted to be out of the southeast due to a low pressure system located back across Texas. These southeast surface winds could enhance the tornado threat across this region. Farther aloft at 850 mb, winds will be relatively weak, struggling to reach 20 knots in most areas. Looking at the jet stream, winds of 40 to 50 knots will exist. While this is not the strongest upper air support for severe weather, it is not terrible thanks to the location of interest being located in the left front quadrant of a jet streak. This should help enhance rising air across the region.
The 0 to 3 km helicity values shown above are relatively low. This could be seen in the hodograph. Despite the great turning of the winds ate the low levels, the winds are relatively weak leaving us with small helicity values. Below are the EHI values yet again showing weaker numbers in advance of the front where the moderate risk exists but better numbers closer to the front. If the RAP is right, these parameters justify why I think the tornado threat will be limited to just a few short lived tornadoes today.
The 12Z NAM model solution however would lead to more tornadoes and possibly a couple long track tornadoes. The hodograph below from about the same area as the RAP hodograph above shows much better turning of the winds and even some stronger winds at the low levels.
This allows for better helicity values over the threat region as shown below.
Additionally, EHI values are much more favorable across the region as shown below.
If all of this comes together as the NAM portrays then the threat would be greater than the RAP believes. However, I am leaning towards the RAP’s forecast as it has tended to be more accurate lately. Either way, it will be interesting to see how the storms play out this afternoon and evening in what could be a very volatile atmosphere across areas of the Southern Plains.
Tomorrow storms will continue to push east as shown below in the SPC Day 2 Probabilistic Outlook. Look for strong winds and large hail to be the main threats with these storms though a couple isolated tornadoes may not be out of the question especially in the Ohio Valley area and back across Texas.