On Friday morning our group woke up in Salina, KS where we discussed possible targets for storms for the day. An MCS came through in the morning causing cloud cover in most of eastern Kansas, limiting thermal instability. With this knowledge, we decided that the game plan would be to try to find the clearing in the cloud cover for storms to possibly initiate by afternoon. So our group headed WSW towards Great Bend, KS in search of a clearing. The outlook for the day was marginal with low instability even in the clear skies. In south central Kansas, CAPE values were around 500 J/kg, which is very weak. CAPE is the Convective Available Potential Energy, which is basically the energy a storm could tap into given that a storm initiates. The other problem was the low shear values around 30 knots. Shear is the direction/speed of wind as it changes with height in the atmosphere. Instability, shear, moisture, and lift are all key in supercell development, maintenance, and strength. In this case, the instability and shear values were on the lower end, however, the moisture convergence boundary was evident extending through south central Kansas providing moisture and lift. Dew points near Greensburg, KS were in the low-mid 60’s, while just an hour west of that dewpoints were in the low 40’s. The cold front extending down through central Kansas into Oklahoma provided sufficient lift to aid in storm initiation. By 3:00 p.m. storms were in firing along this boundary and we were able to follow them as we drove south into Pratt where newer cells initiated. Just outside of Pratt, we stayed with a supercell moving at 20-25mph. This cell showed very broad, weak rotation which inhibits the production of tornadoes. However, this storm did provide great structure along with a fairly strong hail core. Nickel to quarter size hail was reported, but fortunately we were able to stay ahead of this. Below are some pictures highlighting the day.
The class nailed the forecast target area where cells fired up early afternoon and dropped two tornadoes. However, they were high precipitation super cells so unless we got dangerously close we would not be able to see the reported tornadoes as they were rain wrapped. It was a very successful day though, because the students got their forecast right which is what this is all about! Here are some pictures from yesterdays storm. First photo displays the structure of the supercell we were on, second one is of the wall cloud that dropped and was rotating but quickly retreated back up, and third photo is the shelf cloud as we let it approach the van. Hope you enjoy the photos and we plan to recap every chase day. A blog update should be posted later this morning concerning the plan for the day.
The first day of the class started early in Tulsa, OK where the students were learning the daily rituals of the trip. Each morning the students will conduct their own individual surface analysis and state where they would position the van for the best chance in catching storms. Each student will work alone, but come together before leaving with the professors and explain why each of the students chose those particular spots. After a brief forecast discussion and small debates, the selection is made and we hit the road.
Today, the target city was Wichita, KS where the class and professors both feel is the optimal spot for convection and rotating storms. An upper level trough that is slightly negatively tilted is ejecting out of the four corners region northward. Synoptically, that means just east and northeast of the upper level trough is where the maximum positive vorticity advection will take place along with maximum theta-e advections at the surface. At the surface, a low pressure system located near the CO/KS border will translate northward and bring the advancing warm front northward with it. As the low translates northward, as does the warm front, winds at the surface will become from the southeast. Which is favorable for supercellular development given that the winds are veering with height (winds turn clockwise and increase in speed with height). Bulk shear values range from 40 to 60 knots, where 45 is a baseline value for supercellular development. Moisture has recovered nicely from early in the week bringing dew points into the mid 60’s. Instability is expected to increase throughout the day as the warm front advances north, leaving south of the front to clear skies for maximum surface heating.
The thought process of students and professors was to move close with the center of low pressure and advancing warm front at the surface where winds will be veered, moisture advections will be maximized, and instability will be the greatest. Here is a surface analysis done by myself (Lee Campbell). Blue circle indicates our target area, blue line indicates cold front, orange line indicates the dryline, red line indicates the warm front, and green lines indicate dew point values (65, 70), and dashed green lines show the fetch off the Gulf of Mexico indicative of the low level jet.
A recap of today will be posted either tonight or tomorrow morning with the best photos taken from the day. Enjoy your day and wish us luck!
Hello blog readers…
I am happy to report that our annual Fields Methods class has already embarked on our trip across the Great Plains in search of weather and greater understanding.
With any luck (and a little skill), we will be as successful as last year’s group and come back with many good pictures, memories, and learning experiences.
This years group includes: Mitchell Gaines, Nathaniel Shearer, Lee Campbell, Kate Wilson, Dustin Jordan, Olivia Payne, Lindsay Rice, as well as myself (Kyle Berry). The instructors, are the same as last year, as we are led by Dr. Joshua Durkee from here at WKU and his colleague Dr. Grady Dixon.
The next couple of weeks the blog will be very active, as there will be daily updates concerning that day’s weather, pictures, as well as our current location.
For now, we are currently in Arkansas heading for a good nights sleep in Tusla, OK. Tommorow looks to be a “chaseable” day with the target area being somewhere in central Kansas. Expect an update soon…