Latest convective watch issued in the 1972-present record is likely in hours, beating the old record for latest watch by one day (June 17, 1992). That was a HIGH RISK day with major outbreak in our area with wind, large hail & tornadoes.
Although we have had isolated severe weather since the August 2020 derecho (64 mph wind gust Fulton County from November squall line, 1-1.50" hail Montgomery County in spring, likely microburst near Rossville with roof blown off horse barn & trees & limbs down as cap was breached on that 98-degree day last week), the closest a watch has gotten is our southern & southwestern border of the viewing area.
That said, we have seen that first batch of storms come through. Indeed, it was most widespread & heaviest in our far northern to northeastern areas with some rainfall amounts of up to 0.50".
Wind damage occurred north & northeast of the viewing area with trees & powerlines reported down in Elkhart & Allen counties.
A few showers & storms extended as far southwest as Greater Lafayette with 0.01" of rain at our WLFI site & 0.02" at the Purdue Airport.
Covington, Attica, Fowler, Crawfordsville, Kentland did not receive any rain in their gauges.
Temperatures are soaring as of 1:15 p.m. to 88-95 over much of the area with heat indices as high as 106. It is coolest in the far north & northeast with 84-87, but heat indices are 90-96 even there.
It is a bit unclear why we do not have a Heat Advisory (there is one in Illinois), but just know that even without it, it will be dangerously hot today with heat indices area-side varying from near 100 to as high as 111.
It will feel like a blast furnace with that strong southwest wind gusting as high as 42 mph.
We are pretty capped right now (you will notice altocumulus castellanus & duplicatus clouds in the sky this afternoon, rooting above that cap), but storms will rapidly burst through this lid later. There is an outside chance that a couple random storms could pop on outflow boundary from storms this morning in the area this afternoon.
This is the best potential of severe weather event since August 2020 derecho in our area.
There is an SPC ENHANCED RISK of severe weather for the area for later today & this would be high-end ENHANCED to near MODERATE, based on the parameters.
Intense heat & deep BOILING instability or buoyancy of up to 3500-4000 J/kg will support very strong updrafts for storms. We will be on the southern edge of a +70 mph mid & upper jet streak, leading to Effective Bulk Shear of up to 40 knots. Some low-level shift in in the wind from south-southwest to west is noted, leading to some curvature in hodographs. Low-level wind fields from the surface to 5,000' will also be quite strong, pumping in high dew points.
This all translates to multiple rounds of organized storms & storm structures with supercells & bows with threat of corridors of damaging straight-line winds, a few downbursts, some large hail & a tornado or two with again those MODERATE RISK parameters being approached. A few isolated gusts exceeding hurricane-force (75 mph) are likely.
Local flash flooding is possible as storms back build & track over the same areas in this "Ring of Fire" on the periphery of the upper ridge. Some places may receive more than 3" of rainfall, which will be welcome in the intense heat & dryness we are experiencing.
Timing of the severe weather risk is 9 p.m. to 5 a.m., though a few storms may linger in part of the viewing area to as late as 8:30 a.m.
Hopefully, I can shave some hours off of that severe risk.
Thoughts are that we clear & heat back up Saturday afternoon with highs 90-96 with heat indices 97-107.
Some scattered storms are possible late in the day (after 5 p.m. to about 12 a.m. it appears) with severe wind/hail to brief isolated tornado risk, but storm coverage will run 35-45%.
These would occur on the outflow boundary of all of the storms tonight & that outflow boundary will be moving back northward on the strong southwest winds.
You can see outflow boundary depicted in image below & moving back northward Saturday.
One wildcard is the cap, there is some evidence a pretty strong cap or lid may become just strong enough to prevent storm development.
We will monitor.
We will be on the southern edge of continued stronger flow at mid & upper levels & as instability re-charges in the heat (as the ridge re-expands again) a few of these supercell storms are possible.
Sunday, a couple isolated storms are possible with severe wind/hail risk, but storm coverage will run only 25%. However, highs of 92-97 are likely with heat indices 100-111.
Potential of strong cap & lack of the best trigger has caused me to keep storm coverage at that 25%.
Line of storms is possible Monday with strong upper trough & cold front. Timing of the line is unclear, but parameters support SLIGHT to ENHANCED RISK for severe weather with wind as the main threat.
Highs in the 90s are expected Monday unless the line comes through earlier in the day.
This cold front & upper trough should push (eventually) Claudette northeast & eastward once it makes landfall likely as a tropical storm with very low chance of making it to barely Category 1 hurricane (no greater than 75 mph winds).
Tuesday still looks much cooler with highs 73-80 with strong northwest to north wind to 35 mph with lots of sunshine & low humidity.
47-54 is likely Tuesday night, followed by 78-85 Wednesday with skies becoming partly cloudy, then 85-90 Thursday with sunshine. Both days do not look humid.
Friday looks humid with highs 90-95.
A "Ring of Fire" complex of storms is possible Saturday with highs 91-97 with heat indices 98-107.
Parameters suggest ENHANCED RISK. We will monitor & see.
A shot of very PLEASANT, COOLER air will likely follow with highs 75-81 & lows 48-54!
HOWEVER, another heat surge with 90s to 100 will likely return in very early July.