Stormy Forecast & TWISTEX Operations

A lot of local meteorologists have been busy the past couple of weeks, with severe weather coming into the state in the form of large hail, damaging winds, and tornadoes. To add to the severe weather, all of the rain associated with the rounds of thunderstorms have created significant flooding concerns throughout Iowa and other surrounding states. Yesterday and today saw several rivers reach record depths, in some cases blowing away previous records by several feet. A lot of rural roads, and even some major highways, have been closed due to flood waters. Unfortunately, just as the rivers begin to subside another round of severe thunderstorms is on its' way over the state.

Even with only slight chances of rain in the forecast, we managed to have several thunderstorms cut across west-central Iowa this evening. They are now in more of a disorganized complex over central Iowa near the Des Moines metro and surrounding. These storms were able to become severe, with mainly a threat of marginally severe hail, although a few warnings for damaging winds have also been issued. These thunderstorms will likely maintain themselves for a while tonight, working into eastern Iowa within the next several hours.

Tomorrow has a warm front setting up to the north of the state once again, with southerly winds over the state returning moisture quickly throughout the afternoon. This strong moisture return, combined with ever-increasing temperatures, may allow for thunderstorm development once again. The best threat will be over northern Iowa, where they are situated near the warm front, however, a large portion of the state will see at least slight thunderstorm chances. The severe weather threat should once again be for large hail and damaging winds, as shear should stay further west along the front in South Dakota. A overnight complex of storms for Tuesday night isn't out of the question for a large part of the state, as they move out of South Dakota. Highs tomorrow should range from the upper 70s to mid 80s with dewpoints rising into the 60s under southerly winds. Overnight lows in the lower to upper 60s from north to south, and increased thunderstorm chances (especially northwest).

Wednesday sets the stage for the best threat of thunderstorms over the state, and the threat of severe weather (potentially significant) returns as well. A warm front should once again be positioned just to the north of the state in southern Minnesota. A low pressure center is forecasted to maintain in west-central Minnesota along/near the South Dakota border. To the south and southwest of this low, a trailing cold front should slowly move eastward during the day. Both the cold front and warm front should be sufficient to produce thunderstorms during the afternoon, with the potential for all modes of severe weather given shear and instability values of current forecasts. The best threat should once again occur over the eastern third of Nebraska, and the western half of Iowa, as well as nearby vicinities of extreme southeast South Dakota and southwestern Minnesota. More details on this threat in later updates, but definitely something for people to keep an eye and ear on once again. Highs on Wednesday near 80 in the north, to the mid 80s in the south; lows overnight ranging from near 60 in the northwest to near 70 in the southeast. As mentioned, thunderstorms likely during the afternoon over the western half; over the entire state during the overnight.

TWISTEX Update: I will be out chasing once again for this system with the TWISTEX crew, this time operating another vehicle (not the ISU car). Will be in southern South Dakota tomorrow for any potential thunderstorms that may be able to develop before the nighttime hours. An updated forecast for tomorrow's severe weather and TWISTEX operations will be made in the morning. Wednesday will be the main day of this operation, with a target possibly including a portion of western Iowa. Expect the next several updates to be focused on TWISTEX; although beings I'm actually driving a vehicle this time the updates may come less often. Look forward to more though!