AFTERNOON-OVERNIGHT: Sunny to mostly sunny skies are in place across zones 1 and 5 this morning. That is thanks to an area of high pressure that is ridging in from the southwest.
To the north of the forecast zones there is a weak disturbance moving through this morning that has generated some clouds and a couple of light rain showers. We will be watching this disturbance move south through the day. By 2-3 PM a few light showers may occur across western Indiana, but most places will be dry.
Through the evening this disturbance will continue across western Indiana. While most places will remain clear and dry, some clouds and a couple stray showers will be possible across western Indiana through the evening. By 7-8 PM these showers will be very isolated and very light in nature.
Any showers that should remain as we get into the overnight will fade as we lose daytime heating. This will set up for a dry night under mostly clear skies.
Lows will be in the upper 40’s east to mid 50’s west.
SATURDAY: A cold front will be in place to the north of the region early in the day on Saturday. As we progress through the day the front will sag southward into zones 1 and 5. As it does, clouds and rain chances will be on the increase.
Highs on Saturday will be in the mid 70’s north to low 80’s south. Winds will be strong with the front moving through, gusts of 30-40 mph will be possible.
Through the morning into early to mid-afternoon conditions will be dry across zones 1 and 5. However, as the front gets closer isolated to widely scattered rain/storms will develop from the I-70 area northward across Indiana and western Ohio.
By 5-6 PM the front will be located across central Indiana and into central Ohio. Isolated to scattered rain and storms will be occurring near the front.
Through the evening rain and storm chances will increase right along the front. By 7-8 PM we will be watching a developing MCS (Mesoscale Convective System) or cluster of storms enter northwest zone 1 from Illinois. This while more scattered storms continue across the front from eastern Indiana into southern Ohio. Scattered storms will be possible in both the Indianapolis and Cincinnati areas at this time.
This MCS looks to impact the Indianapolis area around 9-10 PM Saturday evening. Then continue off to the southeast.
If the MCS can hold together it would continue southeast along I-74 through the late evening. Likely impacting the Cincinnati area around 12-1 AM. Along the front rain and storms will still be ongoing at 2 AM Sunday morning across zones 1 and 5.
The MCS previously mentioned should develop and move right along the 570 line at 500 mb. This line would place it perfectly from northern Illinois southeastward into Indianapolis and eventually into Cincinnati.
With upper-level winds of 60-70 mph from the northwest at 500 mb and 30-40 mph winds out of the west at 850 mb, there will be upper-level support for strong to severe storms to develop.
Areas of moderate instability will develop along the front Saturday afternoon. CAPE values of 1000-1750 J/Kg will be possible along the cold front Saturday afternoon. This will allow for storms to quickly develop and become strong to severe in some cases Saturday afternoon through the evening.
With upper-level temperatures so cold Saturday, I do think the hail threat will once again be high. Lapse rates of 8.5-9.5° at low-levels would suggest that hail threat.
Main severe risks on Saturday will be hail and damaging winds. However, an isolated tornado or two can’t be ruled out.
Through the overnight rain and storms will lose their steam as we lose instability and the best upper-level dynamics. So while rain will be possible through the overnight, any strong to severe storms threat will diminish.
Lows Saturday night into Sunday will be in the mid 40’s north to mid 50’s south.
SUNDAY: With the front hanging around the area Sunday morning scattered areas of rain and perhaps a few t’storms will be ongoing across Indiana and Ohio. By 7-8 AM the NAM 4km shows the scattered precipitation that’s in place.
With the frontal boundary remaining across southern Indiana scattered rain and storms will remain possible across zones 1 and 5 on Sunday. By 1-2 pm scattered areas of precipitation will be occurring.
Through the afternoon precipitation may actually fade somewhat and rain chances will decrease after 4-5 PM, at least briefly.
Highs on Sunday will be in the low to upper 60’s. Places to the south closer to the front could see temperatures in the low to mid 70’s.
Sunday evening the stationary front will start to slowly lift north. As it does, more areas of rain and some storms will develop ahead of it across zone 5 and southern zone 1 in Indiana. By 9-11 PM scattered areas of rain and thunderstorms will be developing.
Regarding new rainfall across the area, the NAM is very aggressive with rainfall totals across central Indiana where the MCS is forecast to occur. It puts down areas of 3-3.5” of new rain. While that may be a bit excessive, I would not be shocked to see 1.5-2” of rain locally where the most intense part of the MCS moves through.
However, I do think an average of .25-.50” will occur in many areas. This with some spots to the south seeing a bit less and some spots where the heavy storms and MCS move through seeing more.
MONDAY: Through the overnight into Monday morning the warm front will lift northward ahead of an area of low pressure moving towards the region. Lifting along the front will allow for the continuation of rain and some thunderstorms Sunday night into Monday morning from south to north across Indiana and Ohio. Perhaps with more isolated widely scattered precipitation in Ohio.
Late morning through mid-afternoon on Monday could prove to be dry across the forecast area as the warm front will be north of the zones. However, as we gain more instability through the afternoon scattered rain and storms will develop along and near the warm front. These could very well impact northern zone 5 and zone 1 across Indiana and Ohio.
Highs on Monday will be in the low to upper 70s. Winds will be strong at times with 30-35 mph gusts possible.
MONDAY NIGHT – WEDNESDAY: A bit of a complicated scenario is setting up by next Monday night. This will be as the low start to slow as it heads eastward into the region.
Models are really having issues with timing of the cold front next week. The EURO and CMC suggest the front passes Tuesday afternoon and into the overnight from west to east across the forecast region.
However, the GFS is nearly 24 hours slower with the frontal passage, brining into though on Wednesday.
Overall, I do tend to favor the faster EURO/CMC solution. The current pattern, while slow with exiting the initial sagging cold fronts, has been quicker on eastward propagating cold fronts.
Regarding severe weather next week, many things will need fine-tuned to forecast the severe weather threat, if there is any. Right now models are pretty messy with this system, so we will have to see the progression of the models/forecast over the next several days.
LONG RANGE: An area of high pressure looks to move into the region mid to late next week as the system exits the region. While this will give us a short break from the active pattern more rain and storms will return to the forecast.
By late next week we will be watching another developing system that will have the potential to spread rain and storms back into the region next THU/FRI.