Indiana Weather Outlook 12-15-17

High pressure starts to move off to the east today and that will allow for more west and southwest winds to emerge. We will not see temps immediately respond with warming, but our cold push should stop. Better temperature moderation is likely tomorrow. Clouds clear out over most of the state today, but will hold in northern areas, and there still can be some lake snows developing in western Michigan that try to drift slightly south. Southwest winds start to increase in velocity tomorrow.

Sunday still looks to turn wet, but rains wait a little longer to move into the state. Also, the rain totals will likely be a little lower as the system lacks intensity at this point. Rains start in SW Indiana shortly after noon, and then spread north and east from there. We like rain totals of .1”-.4” over 90% of the state. We have no concern about rains over half an inch any more. The bulk of the rains will be done by midnight. Clouds linger overnight through Monday, though, and that will lead to a somewhat damp feel, even a bit of drizzle in there behind the system.

Tuesday, Wednesday and Thursday look dry, with a good deal of sun in for Tuesday and Wednesday. Temps will be normal to above normal for the period, as southwest winds hold through the period. Thursday will feature some cloud increase, ahead of a front for overnight Thursday into Friday the 22nd. That front is not loaded with moisture, but still will be worth a few hundredths to .25” of rain over 90% of the state. We will see very, very strong winds develop as the front passes and behind it. Those winds behind the front will be out of the west-northwest and will average 20-40 mph. This is a very strong circulation that so far, has looked to be unable to tap into any moisture source. That is what we will be watching through the week next week, because if it is able to gain access to any moisture, say – off of the Gulf – it will be a much wetter event. For now, just wind and a little rain.

Much colder air is in behind that system for the balance of Friday the 22nd into the weekend ahead of Christmas. Northwest winds may create some lake effect snows in northcentral Indiana, but generally, we are not looking for as significant of spread of lake snows and lake clouds as what we have seen over the past week. The map above shows totals 10 day rains over the state between now and Christmas Eve. Even though it seems like an active pattern here, true moisture from these waves is limited in general.

There’s a significant storm complex developing in and around Christmas. This storm comes out of the southern plains, skims the gulf coast and then heads northeast through the mid and lower Mississippi valley around the 24th-25th. That track allows for ample moisture to be available. Cold air should solidly be in place too, meaning this could be a recipe for some significant winter weather for that period from Christmas Eve to the 26th. However, at this time, we think the track is too far south for us to be in the main firing line of heaviest moisture. That being said…there is plenty of time for the track to move and change, so it is definitely worth keeping an eye on. The rest of the 11-16 day forecast window has two strong, cold high pressure domes moving in from NW to SE right on through the turn of the year, meaning we finish 2017 cold…perhaps well below normal.

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