We’re not even through the first 1/4 of this rain event, and we’ve already had several flash flood warnings issued today. Periods of rain, occasionally heavy, will continue through central IN through the weekend. Additional flash flood warnings will come. As of this report, localized rainfall totals are approaching 3″ in a few spots (Greencastle area, between Vincennes and Bedford, and around Muncie).
As mentioned, this is a long-duration event, but there will be dry times. Perhaps the most widespread heavy rains arrive on the scene late Sunday night into early next week. Monday into Tuesday looks very wet. The moisture and energy associated with the area of low pressure over Louisiana will meander northwest over the next (24) hours before moving north and eventually northeast along the frontal boundary that will be stalled over the region.
Precipitable water will once again surge to 2.5″+ and promote intense rainfall rates over a more widespread portion of the region Sunday night through Tuesday.
Unlike the localized banding features of the rain today, the rain shield should be much more widespread Monday into Tuesday. Factor in the hefty rain totals today into Sunday, combined with additional heavy rain Monday and Tuesday, and it wouldn’t surprise us to see a few double digit rainfall reports by the time all is said and done Wednesday night/ Thursday. Widespread 4″+ totals will be common across central IN by the time all is said and done.
We flip the script next weekend and turn much drier and unseasonably cool. It’ll feel like an early taste of fall next weekend (perhaps even some upper 40s for a few folks across central portions of the state)?!
Heed flood warnings that come over the next few days. Rainfall rates will be downright tropical in nature and result in fast water rise.
Despite lackluster model output from our American suite (latest NAM and SREF data, for instance, paints rainfall totals under 1″ across most central IN neighborhoods), the European remains consistent on the evolution of things from this weekend into the middle of next week. We’ll lean more towards it’s solution at this juncture. Simply put, when you have a stalled frontal boundary entraining tropical moisture, expect problems. Precipitable water values will approach and even exceed 2″ at times this weekend. Dew points will remain in the upper 60s to lower 70s along and south of the boundary. Where the boundary stalls will be key in determining the heaviest rain totals and resulting flood problems that will ensue. For now, here’s the best idea we have in regards to local 4″+ totals between this weekend and next Wednesday.
It should also be pointed out that we’re not looking at all day rains Saturday through Wednesday, but instead “waves” of moisture throughout the period. Areas of locally heavy rain will be with us, but we’ll also see dry periods in between. Thankfully, as we move into the latter portions of next week, drier times should return.
The precise placement of the front will serve as the focal point for heavy weekend rains. As we’d expect from this distance, modeling disagrees on the all-important specifics. Using a model blend, central Indiana is on the table for heavy late week-weekend rain as of now. Precipitable water values (PWATs) will be above 2″ and suggest the threat of torrential downpours, including localized flash flooding across the Ohio Valley. Eventually, the cold front will sweep the tropical-rich moisture away from the region and cooler, much less humid air will press in by this time next week.
The atmosphere will be loaded with moisture and precipitable water values (2″+) will promote localized flash flooding within the storm complexes.
We think the initial wave of storms will ride southeast late tonight and early Monday and could encompass SW portions of the forecast area. The pattern is favorable for additional storm complexes to travel southeast Tuesday and Wednesday, however.
That said, things will change as we progress into the prime heating hours of the afternoon and evening. Upper level energy will rotate east out of the Plains (this morning) and across Indiana this afternoon and evening.
This will help ignite thunderstorm development during the afternoon and evening. While a storm could impact any given neighborhood this evening, best concentration of storms should lie north of the I-70 corridor. Locally heavy rain will be a good bet with the stronger storms. Localized rainfall amounts in excess of 2″ will be possible.
Additional scattered thunderstorm activity will continue Saturday, but there will be many more dry hours than wet/ stormy.