Severe Weather (Wed/Thur)

TWISTEX Update: Crews have all returned home, with us once again waiting for another good severe weather threat with westerly or southwesterly flow aloft. Although severe weather is likely over the northern plains, winds aloft are from the northwest and are not usually considered as the best when it comes to a tornadic supercell threat. Thus, deployment not likely until this weekend when a belt of westerly and southwesterly winds become possible over the far northern plains. This is currently the highlighted area for watching, possible deployment for the weekend and into Monday as of current forecasts...
Adding the last chase trip, I have now logged in 3,608.59 miles with the TWISTEX crew and over 75 hours of on-the-road driving.

A severe weather threat is likely over the plains states tomorrow and Thursday, with Iowa being involved in both days. Although cooler today, with much less moisture over the state and other areas of the northern plains will quickly evolve into warm and humid by as early as tomorrow. Strong moisture gradient is currently noted over KS/MO where at least mid 60s dewpoints are noted. This moisture is likely to surge northward today/tonight and through Thursday, allowing mid 60s to upper 60s dewpoints as far north as SD/MN. This moisture return along with strong heating will allow for moderate to strong instability over the plains states on both days. A warm front is likely to settle into portions of SD/MN during both days and a cold front, possible dryline will be near stationary over SD/NE. These two areas will be the focus for severe weather development...

On Wednesday, on the eastern edge of a cap (warmer temperatures aloft) thunderstorms will likely develop during the late afternoon, evening hours. These thunderstorms will likely be capable of large hail and damaging winds; isolated tornadoes may also be possible, especially over areas of southeastern SD. This threat is likely to congeal into a linear line of thunderstorms or an MCS that travels eastward through the nighttime hours. This MCS is likely to reach the IA and MN area by early morning on Thursday with the potential for damaging winds most likely...

Thursday morning will allow the MCS from previous night move out of Iowa, possibly continuing its' severe threat of damaging winds into the Ohio Valley by Thursday evening. Additional thunderstorm development seems likely over possibly two areas; one along the cold front/stationary boundary in central & eastern SD/NE and the other along the warm front through northern Iowa. Both boundaries may be able to initiate thunderstorms capable of large hail and isolated tornadoes. Currently the forecasts indicate that the best tornadic potential may indeed be over portions of Iowa during the evening hours. However with this threat still a decent time out in the forecast, expect subtle changes in the threats and their locations by tomorrow. It is definitely going to be a couple of days in which Iowans should keep an eye out for severe weather.