In the bitter cold of this morning, Angela Hinkle Zimmerman caught this image of a well-formed halo! Angle of the ice crystals has to be 60 to 90 degrees & they all be uniform to get such a great halo to form.
It can be so cold that ice crystals falling from a clear sky, as the airmass cannot hold the moisture. Also, you can have ice crystals form on particles of dust that create this phenomenon in a clear sky (also called diamond dust).
We had similar phenomonena when we dropped to -20 last January.
Coldest low temperatures this morning were found over southeastern Tippecanoe & far western Clinton County with -13 to -10. Another pocket in Benton & far western Newton County saw lows -11 to -10. Just west of Newton County, Momence, Illinois dropped to -15.
In Tippecanoe County, some numbers included -12 Clark's Hill.....-11 Stockwell.....-8 Concord; Sharon Chapel Road Just North of Newman Road; 5 Miles South of Odell; Purdue Ag Farm 6 Miles Northwest of West Lafayette.....-6 WLFI ob site; Blackthorn; Corwin.....-4 Purdue Airport; 52 & Veteran's Memorial.....-3 Benjamin Crossing
BTW....Monticello, Frankfort & New Market observation sites are not functioning due to some sort of AWOS outage. So, those three airport stations will be unavailable for an unknown amount of time.
Wind chills dropped to -23 to -12.
The -8 this morning at the Ag Farm (official site for modern-day 1879-present data set) was the second coldest on record for February 14.
Only 1988 was close with -7. The record coldest Valentine's Day was -22 in 1905.
Some scattered snow, sleet, freezing rain & rain are possible Saturday afternoon-night before exiting early Sunday morning.
Any ice or snow accumulation would be light & amount to a localized dusting/coating. Still, watch for a few slick spots.
Highs will reach 34-38 late Saturday.
Winds will be strong from the south-southwest with gusts 30-40 mph at times. This will lead to blowing & drifting snow & perhaps a very narrow window for snow rollers.
It will not be as windy Sunday (from west-northwest to northwest direction) with mostly cloudy skies & temperatures in the 30s.
Rain will move in Monday with the heaviest falling Monday night to early Tuesday before ending. Winds will be strong from the south Monday night with a big temperature rise from 30s & 40s to 40s & 50s.
Strong northwest winds to 40 mph will follow front Tuesday midday-afternoon with falling temperatures into the 30s, then 20s.
It looks mostly cloudy to cloudy for the afternoon (with a few flurries), followed by some clearing Tuesday night with lows 15-19 (wind chill to -2).
Around 1" of rainfall is possible with this system atop frozen, snow-covered ground. This with high rainfall rates Monday night will result in creek & stream rises & potential of some local ice jamming.
Clipper will pass Thursday with round of snow showers with very minor accumulation of 1" or less.
Friday should turn mostly sunny & windy (gusts to 30 mph) with highs of 33-37.
Temperatures will be steady at 31-34, then rise to 35-40 Friday night (gusts to 30 mph).
Cold front should pass Saturday morning & plateau temperatures at around 37-41, then falling to 32-36 (with mostly cloudy skies).