JAB OF COLD
Friday afternoon was a cold one in central Indiana – coldest in 10 days. Afternoon temperature held steady in the lower to middle teens with a wind chill of -5° in the city at 5 PM. A chunk of arctic air rolled will ease out of the state overnight but not before some thermometers dip into the single digits. Winds from the south will ease up but still be enough to produce a wind chill below zero through Saturday morning. JANUARY SNOW ON RECORD PACE AS of Friday this January has produced 20.9” of snow – already ties for the 5th snowiest January on record with January 1977 and is 450% the normal snow to date. Normally we have 4.6” of snow through the 17th. Only 4 other January’s on record have produced this much snow to date. Seasonal snowfall is now 29.8”. If no more snow fall the rest of the winter, this will be the 3oth snowiest on record. (And that’s not going to happen)
Here comes another fast-moving low pressure system diving out of the upper Midwest. Snow will return here getting under way sometime around 2 PM in the city. The system riding the cold jet stream will bring a stripe of 3” to 5” of snow through central Indiana then end quickly after midnight. These “clipper” systems (named after the fast-moving ships that sailed the Atlantic Ocean in the mid 1800’s) are often starved for moist air but what they lack in moisture they make up for in upper air support. The energy this system delivers is often compact and robust and will squeeze out all the moisture to bring a band of impressive snowfall. The storm track is key because amounts drop off quickly north and south of the storms track axis. The present forecast brings the heat of this snow right thought central Indiana. These storms bring a drier or fluffy snow with them – the standard rain to snow ratio of 10:1 (every inch of rain = 10” of snow) is augmented when cold air is present. We will get more “bang for the buck” with a rain to snow ratio closer to 20:1. A 7 model computer average snowfall for the city comes in at 3.2” with a range from 2.1” to 5.2”. We lean-to the higher total given the current storm track.
COLD WAVE COMING
Several days of overnight computer runs off various long-range models are locked into very cold air coming again and locking into finish off the month. The core of the cold air – the “polar vortex” is on the move later next week. We bring the southern flank of the cold in starting early next week, dropping afternoon temperatures into the lower teens and overnight lows forecast to go below zero. Attention the turns to the core of the cold coming in full-bodied over the eastern U.S. This would be a return of the “polar vortex” and bring even colder air south. Some computers indicate afternoon high temps may fail to reach 10°.