Your Monday

Most recent La Nina numbers hold steady at -1.0 in the nino 3.4 region. Has held fairly steady now for the past couple of weeks. There is a 'normal' look to the East Asian jet but still allowed warmer readings for the east U.S for much of the week. Will this overall theme continue?

If the East Asian jet continues its normal look, expect colder air to infiltrate the northern U.S. with above average snowfall. Some of that colder air will dive into parts of the southern U.S.; however, moisture output could be limited without access to the Gulf of Mexico on the backside of any cold fronts. Cold air should not be long-lasting though for our region.

Interestingly, a sharp w-e demarcation line could set up over the next several days where very cold air will be separated by a boundary of much warmer, modified air to the south.

Any amplification of that line will push it one way or the other. My main concern would be ice for some, while others could get their heaviest snow of the season. It's still too early to tell how this feature could set up if it sets up at all. But, professional mets out there, pay attention to the East Asian jet.
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NAO forecasts are mixed. Ensembles out 14 days are split nearly even on whether the NAO drops below zero. Op GFS suggests more positive readings after mid-month following a dip to near zero for this week.
Therefore, no long term blocking pattern yet. We'll see colder readings here, just won't stick around to get comfortable. Look for progressive systems to affect the U.S. over the next week to 10 days. Again, main concern will be how the East Asian jet interacts with the overall pattern.. A pattern of cold air could set up over the northern half of the U.S. with impacts on our region locally later in the 14-day period.
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The latest GEM 10-day snowfall outlook is back to showing its usual miniscule 1.0" for Louisville area after spiking on news of a secondary low that could form in the Gulf.

The latest GFS 10-day snowfall outlook is also back to 'normal', showing up to an inch for the area.
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As far as the cold air expected to slam the region late week, temperatures look to drop into mid and upper teens for lows while struggling to reach 30-32 for highs in Louisville by the weekend with only minor modification thru Tuesday of next week. Still looks generally dry thru that period. Afterward, expect moderation in temperatures with rain chances going up after Wednesday of next week. That's when I think things could get interesting here. Mark your calendars for January 18-20 period. Nothing seriously wintry till then at least in terms of precipitation.

MS