AFTERNOON-OVERNIGHT: Filtered sunshine remains in place across most of zones 1 and 5 with some thicker clouds moving in across southwestern zone 5. A few showers are to the forecast areas west, however right now, conditions are dry across the zones.
By 1-2 PM this afternoon scattered areas of rain and a couple t’storms will become possible across southwestern Indiana in zone 5. However, with dry air in place, I doubt these will amount too much.
Through the afternoon into the evening dry conditions are expected across most places. However, a few areas of rain and a few t’storms will remain possible across western zone 5. By 5-6 PM showers and storms will be exiting to the south of the forecast area.
Through the evening into the overnight an upper-level vorticity max will be moving through Illinois. Rain and thunderstorms look to develop along this area of vorticity this afternoon and into this evening across Iowa, Missouri, and western Illinois.
This will track east with the vorticity max. While it currently looks like the 500 mb vorticity max and the rain with it will be fading out as it works east overnight. Some of that rain and maybe a few t’storms could enter western Indiana by 2-3 AM.
Overnight some new rain and a few storms will develop ahead of the upper-level energy across Indiana and western Ohio. By 4-5 AM those isolated to scattered areas of precipitation will be ongoing.
Lows overnight will be in the upper 50’s north to mid 60’s southwest.
WEDNESDAY: As the upper-level energy continues to move across Indiana Wednesday morning scattered area of rain and some t’storms will develop across Indiana and into western Ohio. By 7-8 AM the NAM 4km is pretty aggressive with rain and storms across Indiana.
Through the morning the 500 mb energy will move off to the east continuing to weaken. The rain and storm coverage will decrease through the morning hours on Wednesday. By 1-2 PM only some isolated to widely scattered storms will be ongoing across Indiana and southern Ohio.
Through the afternoon hours on Wednesday a few isolated storms may stick around. However, I do expect a bit of a lull in activity. The latest models do suggest clearing through the afternoon as well. If this were to occur instability would build in quickly across the region given the warm, moist environment. The latest NAM 12km model shows CAPE values of 1200-1600 J/Kg across portions of the forecast area.
While models do not develop more than a few isolated areas of rain and storms in the area tomorrow afternoon/evening, I would not be shocked to see chances rise later on in model runs. Especially given the fact another upper-level piece of energy will be moving into Indiana later on Wednesday evening around 8-9 PM. Many times rain and storms will develop along an ahead of these areas of energy.
Highs on Wednesday will be in the upper 70’s east to mid 80’s southwest. Winds will be strong at times with gusts of 20-30 mph possible.
Wednesday night the upper-level energy will weaken as it moves east. With that weakening and instability fading, any leftover rain and storms should start to do the same. So while some isolated rain and a storm or two will be possible Wednesday night most areas will be dry.
While a few storms could be strong to maybe low-end severe Wednesday afternoon/evening, most will be short of severe limits with gusty winds, hail, and heavy rain the main threats.
THURSDAY: Late Wednesday night modes continue to hint of the possibility of a MCS type structure impacting the forecast region. The NAM 12 km model and the EURO suggest a cluster of storms forms in northern Illinois and northern Indiana around 4-5 AM Thursday morning.
Through the morning hours this would track to the east and southeast, possibly impacting northern and eastern Indiana, then into western/southwestern Ohio. By 8 AM the NAM model does show areas of rain and t’storms in the area along with upper-level energy moving across the forecast area. However, these MCS/cluster type storms can be very tricky to forecast so we will fine-tune placement, timing, and impacts over the next 24 hours or so.
As that area of rain and storms move out of the region through the morning hours on Thursday rain and clouds look to clear out behind it. As the skies clear instability will build through the day. The NAM 12 km has 3000-4200 J/Kg of CAPE Thursday afternoon across a widespread area!
With the high amounts of CAPE and a warm, saturated environment I do think t’storms will once again form by 4-5 PM Thursday afternoon across Indiana and into Ohio.
Highs on Thursday will be in the upper 70’s to mid 80’s. Winds will be strong with gusts of 20-30 mph.
Thursday evening scattered rain and storms will be ongoing across zones 1 and 5 in Indiana and Ohio. By 7-8 PM the NAM 4km shows those storms right along the I-70 corridor from Indiana through central Ohio.
Through the evening I expect these areas of rain and storms to move out of the forecast area. Without the aid of daytime heating the rain and storms should start to fade out in both intensity and coverage.
While upper-level winds are weak, high amounts of CAPE and very high dew points in the 70’s, could be enough to cause some severe downbursts within the storms. However, I am not expecting any large-scale severe weather.
Thursday evening into the overnight rain and storms will fade and move out of the forecast area. This will set up for a calm overnight. With lows in the 60’s.
FRIDAY: Across zones 1 and 5 on Friday most of the day does look dry. However, by 4-5 PM t’storms will likely develop across western Indiana as a front moves to the west of the forecast area.
Through the evening storms chances look to remain across western Indiana. By 8-9 PM isolated to scattered t’storms will be ongoing.
Through the afternoon on Friday better upper-level dynamics will arrive across Illinois and perhaps western Indiana.
Instability is forecast to increase across portions of the forecast zones as well. With upper-level wind fields, instability, and lots of moisture in place strong to severe storms will be possible across portions of the zones. However, there are many details that need worked out as we get closer to the forecast period.
Highs on Friday will be in the upper 70’s to mid 80’s.
Some pretty heavy rainfall totals look likely across portions of zones 1 and 5 through the end of the weekend. The GFS shows many places getting between .75-1.25” of new rainfall.
However, the NAM 4km shows some of the locally higher amounts. Areas were strong to severe storms or a storm complex moves through could see 3-4” of new rainfall! With already saturated ground some localized flash flooding could become a problem with the heavier t’storms.
WEEKEND: The warm front will lift northward through the region Friday through Friday night leaving us in the warm sector of the storm system for the weekend. While it will be very warm and humid this weekend, rain/storm chances will be lower. Right now only isolated to widely scattered afternoon pop up storms look possible both Saturday and Sunday.
Highs this weekend will be very warm with highs in the upper 70’s to mid 80’s Saturday.
Sunday even warmer air will spread in with highs in the low 80’s to possibly near 90 in locations!