By: Stephen McCoy

Precipitation chances have diminished somewhat for the remaining practice days for the Indianapolis 500. Otherwise, conditions are staying mostly as-expected from Monday's initial forecast.

For Thursday and Friday, a surface high pressure system currently located over the Great Lakes region is expected to move towards the northeast into eastern Canada by Friday evening. The anticyclonic rotation around the high will cause surface winds mainly from the northeast each day, with a slight change to the east during the second half of Friday. A temperature inversion in the low levels of the atmosphere will inhibit convective development on Thursday and resulting in partly cloudy conditions for much of the day. Low level winds from the east/northeast on Friday will erode the inversion and allow for a slight chance for afternoon showers and/or thunderstorms around the region.

For Saturday and Sunday, an upper level low pressure trough will develop over the Missouri River Valley during Friday afternoon and into the overnight. The trough will cause a surface low pressure system to form over Tennessee/Kentucky and push northeastward through the weekend. Moisture in the lower levels will bring a chance for showers during Saturday as the low passes to the east of central Indiana. As the system continues its movement towards New England, winds in the region will shift to the north to northwest, possibly resulting in some slightly cooler temperatures, though model guidance shows uncertainty in the maximum on Sunday.

By: Stephen McCoy

There are no major surprises in the forecast for this week's practice and qualifying sessions for the Indianapolis 500: maximum temperatures are expected the mid 80's with chances for afternoon showers and/or thunderstorms.

For Wednesday through Friday, an upper level ridge over the southwestern US will influence a high pressure system at the surface, moving it northeastward through the Great Lakes region. For much of the time period, surface winds will be relatively light from the east to northeast, accompanied by partly cloudy skies. Dew point temperatures in the mid 60's could give enough convective inhibition to result in isolated to scattered showers and thunderstorms in the afternoon around the area.

For Saturday and Sunday, conditions are anticipated to be similar to those earlier in the week, however towards early Saturday afternoon, a cold front will move eastward through central Indiana, bringing with it an increased chance for precipitation, with the greatest chance occurring in the overnight hours. Winds during the day will be from the south to southwest with partly to mostly cloudy skies. After the front passes through, winds will shift towards the north to northwest for Sunday, accompanied by clearer conditions. Much like earlier in the week, a slight chance for showers and thunderstorms is present during the afternoon.

By Scott Martin

The activities taking place at and on the track on Saturday will stay dry as we'll have plenty of sunshine bathing the straights and twisty turns of Road America. Temperatures will start off around 62 degrees at 8:00 am underneath mainly sunny skies. There will be a few clouds to help shade you from the sun for a few minutes at a time once we get to the afternoon, but you will still need the shades, the hats, and the sunscreen. Afternoon highs look to top out at a very comfortable 78 degrees. Winds will be shifty throughout the day out of the north with some fluctuations out of the east and northeast at 5-10 MPH. Chance of any measurable rain is at 0%.

An impulse will be moving across Wisconsin throughout the day on Sunday that will bring a little lift and moisture to the area, especially during the afternoon hours. If any rain occurs, it doesn't look like it will be heavy and shouldn't cause a red flag. So, there is a 50/50 chance you may see the best racers in the world struggling for grip on a wet track. Temperatures start off around 69 degrees at 8:00 am and will warm up to around 76 degrees for the daytime high. Skies will start off partly cloudy, but more clouds will build throughout the morning and will be mostly cloudy by afternoon. Rain looks to become possible right around 12:00 pm and will be possible the afternoon and into the early evening. Winds will be out of the north to northeast at 5-10 MPH. Once again, rain chances will be around 50% for now.

By Doug Schneider

Not much has changed in the forecast for Friday and Saturday at Sebring since my initial forecast on Tuesday. A tropical upper level low pressure system is expected to move slowly west across southern Florida, which will enhance the chance of afternoon showers and thunderstorms both day.

The main impact of any showers and thunderstorms will be lightning and very heavy rainfall. Because of the potential for heavy rain to cause ponding of water on the track, and relatively high confidence of storms occurring, I have rated the Impact as Moderate. Some sessions or races may need to be stopped for a period. The good news is that any showers or storms should be short-lived, lasting maybe 20-40 minutes on average. For both Friday and Saturday, the most likely time period for showers and storms will be between 2 pm and 6 pm. 

By: Stephen McCoy

Precipitation chances for this weekend have shifted more towards overnight Friday into Saturday morning, posing little to no threat to on track sessions. Hot conditions are still expected to be present, with daily high temperatures in the upper 80's to low 90's anticipated. Dew point temperatures in the mid 70's will result in heat index values or "feels like" temperatures around 100 degrees. Though air temperatures may cool a bit in time for the races, dew point temperatures are expected to increase into the evening, causing heat index values to remain mostly consistent through the latter half of each day. Strong southerly winds in the low levels of the atmosphere will increase wind speeds at the surface, resulting in breezy conditions for Saturday afternoon.