Two changes to the ongoing Storm Watch. First: it now starts 7pm Monday. Secondly: the area has expanded, and there’s also a Blizzard Watch in place in northwest Indiana.
The main thing remains: both significant snowfall and significant ice accumulations are possible.
Computer model guidance is all in the same ballpark, but this is really the first model run in which the low has moved onshore into the upper air network, so there will be more certainty tomorrow regarding the exact track of the system. Additionally, trends in recent runs have been slowly but steadily pulling the low to the northwest, as is often seen with such strong systems, and this could have an enormous impact on the resultant snow and ice across the area. Whereas current thinking is that the heavy snow axis will brush northwestern portions of central Indiana (with the major icing axis roughly along the I-70 corridor) continued northwest trends could shift all these northwest as well. That would put more areas under the treat of ice.
TECHNICAL DISCUSSION FROM THE WEATHER SERVICE:
System is strongly forced really no matter how one chooses to quantify it. Models continue to advertise a coupled upper level jet structure…along with an incredibly strong southerly low level jet ahead of the system…60 to 80kts at 850 mb. strong frontogenetical forcing is noted…especially tuesday and tuesday
night. strong q vector convergence aloft is also noted…again especially tuesday and tuesday night.
Forecast soundings continue to display classic freezing rain profiles tomorrow night and much of tuesday…although with very low lower level wetbulb temps may see things briefly start late
tomorrow afternoon into the evening as snow before rapidly transitioning to freezing rain or a mix with sleet.
As warm advection increases ahead of the low into tuesday and tuesday night…freezing rain or mixed precip zone will push even further north…perhaps allowing a transition to just rain over southern tier of central indiana. as low passes late tuesday night into wednesday…strong cold advection will allow a transition to all snow. in addition…very strong surface pressure gradient will produce gusty winds…perhaps as high as 35 to 40 mph. this coupled with significant snow and ice may cause damage to trees…power lines…and perhaps some structures…even after the heaviest precipitation has ended…and may complicate recovery efforts after the fact.
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