You can't rely on anything more than 3 days out. A week to ten days ago all the data suggested that February was going to be warm and above average in temperatures. A week before that the data suggested that the polar vortex would arrive last week. Now it looks like the polar vortex is set to arrive next week but that could also change. Keep an eye on your weather apps but don't trust them past the third day. Here is the latest analysis from the National Weather Service office out of Indianapolis:
.SHORT TERM /Tonight through Wednesday Night/... Issued at 224 AM EST Mon Feb 1 2021 Strong subsidence throughout the short term period will keep conditions dry as a broad area of high pressure overtakes the central U.S. The ridge axis is progged to be over the Plains by tonight, shifting eastward throughout the short term period and eventually reaching the Great Lakes Region on Wednesday night. The strong northerly winds will persist into tonight with gusts up to 25 mph, but the gradient will begin to relax a bit by Tuesday. The northerly flow will help keep temperatures below normal though for most of the period with lows dipping into the teens and 20s tonight and Tuesday night, and daytime highs only topping off in the upper 20s to mid 30s on Tuesday. However, as the surface flow becomes southerly on Wednesday, a brief warming trend will commence. Daytime highs on Wednesday will top off in the low to upper 30s with slightly warmer temperatures in the low to upper 20s on Wednesday night. && .LONG TERM /Thursday through Monday/... Issued at 258 AM EST Mon Feb 1 2021 The long term will focus on two features, helping produce precipitation on Thursday and then sub-seasonal temperatures next weekend. A low pressure system will begin to develop in the lee of the Rockies Wednesday, moving eastward along a neutrally oriented upper level trough. Primary cyclogenesis will be within the left exit region of a 400-300mb upper level jet. The lack of significant advection and dynamic alignment should keep this system rather mundane. However, an influx of moisture out ahead of the trough will help invigorate precipitation development slightly, with overall QPF totals expected between 0.25"-0.5" over central Indiana. P-type should mostly be rain as central Indiana is located within the warm sector, although some mixed precipitation during onset is possible. Further into the period a majority of ensemble members are in decent agreement, especially for 150+ hours out, indicating strongly below seasonal temperatures next weekend. A positively tilted mid to upper level trough will reinforce the the southward progression of an arctic airmass into the eastern half of the CONUS. This is supported by a strongly negative AO depicting weak inertial stability of the polar jet. Given this combination of factors, confidence in a cold snap during days 6 through 7 is trending upwards. Current ensemble means are showing 1000-500mb thickness values below 4900 indicative of an extremely cold air mass. Although, exact temperature values are hard to predict and will vary as models ingest observations in the coming days. Overnight lows on Saturday night are expected to be in the single digits, but below zero values are not out of the realm of possibilities.
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