A warm front is draped across the state this evening. At the same time, surface low pressure is spinning across north-central MO with a trailing cold front entering IL. This evening, a warm and moist airmass continues to advect into central Indiana.
As we type this update, widely scattered thunderstorms are impacting areas from Lafayette to the northeast side of Indianapolis. A more organized complex of thunderstorms is firing to our southwest- from south-central IL to southeastern MO and into AR. This is ahead of the cold front.
Looking at forecast radar products, the majority of data brings a couple rounds of showers and thunderstorms through central parts of the state around 9p to 10p, continuing into the overnight and predawn hours.
9p forecast radar
11p forecast radar
2a forecast radar
5a forecast radar
With high precipitable water values in place (approaching 2″ through tonight), locally heavy rain is likely with thunderstorms through the night. We expect widespread additional rainfall tonight of 0.50″ to 1″ with locally heavier amounts. A few embedded strong to severe storms are also possible tonight with the primary concern being damaging straight line winds and large hail, but an isolated quick spin-up tornado can’t be ruled out. We suggest ensuring your weather radio is set with the ‘alert mode’ on tonight.
As we flip the page, a few scattered showers will remain in our forecast Tuesday PM before a much cooler and drier air mass invades Tuesday evening- continuing into Friday morning. Several central Indiana neighborhoods will dip into the 40s Thursday and Friday mornings.
2a forecast temperatures Thursday.
Enjoy the cooler air while you’ve got it, as a developing heat wave will engulf much of the region as we close the month and open September. Needless to say, despite the unofficial end to summer just around the corner, there’s still plenty of summer left in the tank. This is the type pattern that can produce an extended stretch of lows around 70° and highs around 90°.
Rain and embedded thunder will likely be rather widespread early Monday, especially across the southern half of the state.
Data continues to point towards the greatest coverage of rainfall arriving Monday night and Tuesday. We still expect a widespread 1″ to 2″ rain for central Indiana before things begin to wind down mid to late week. There will be locally heavier totals.
The model has support of a return to wetter times as noted from the latest JMA Weeklies, CFSv2, and European ensemble.
While the cool will relax as we rumble past the first couple days of the month (we’re in the “dog days” after all), I still think the worst of the heat is over for the summer and the headline for August will likely be a situation where we begin to make up for lost time in the precipitation department. That upper ridge centered to our west in the means will likely result in a continuation of rather active times from a precipitation perspective through the month and our idea is that we finish August with above normal precipitation across central Indiana for the first time since April…
As we look ahead, our weekend weather will continue to be dominated by a “cut off” area of low pressure. As it meanders around the region, shower and thunderstorm chances will remain. Aerial coverage of rain will reach greatest heights during the afternoon and evening hours today and Sunday. With the colder air aloft, don’t be surprised if a few of the stronger showers produce hail.
Additionally, highs today will run close to 10° below the average high of the mid-80s.
Longer term, the NEW JMA Weeklies suggest the worst of the summer heat is now behind us as they keeps the Weeks 3-4 time period unseasonably refreshing…