December 29, 2016 archive

Shift Back To A Cold Pattern Awaits; What About Winter Storm Potential?

December-to-date is running colder than normal (to the tune of 2.2 degrees at IND), but the past (7) days has seen a flip in the frigid 1st half of the month.

December temperature anomalies, courtesy of Weatherbell.com.

December temperature anomalies, courtesy of Weatherbell.com.

Temperature anomalies the last 7 days. Courtesy of Weatherbell.com.

Temperature anomalies the last 7 days. Courtesy of Weatherbell.com.

The “relaxation” is temporary.  Modeling continues to advertise the recent “thaw” will give way to increasingly bitter times as we get deeper into the New Year.  By New Year’s Day we note the positive heights continuing to establish themselves across Alaska and Greenland (cold and stormy signal).  We also note the southeast ridge present, though to a lesser degree than over the past week.

jan1By Day (10), the cold pattern is well established over the Lower 48.  This is a coast-to-coast cold signal (heart of the cold centered over the west and central) depicted by the European ensemble, along with other modeling.

day10

ecmwf-ens_t850amean_namer_6Teleconnections support a cold pattern returning.

epowpo122916

aonao122916

pnaThe agreement amongst teleconnections is nice to see and ups confidence in the overall direction of where this pattern is heading in regards to colder than average times looming.  The negative PNA correlates nicely with the SE ridge that continues to make itself heard from time to time over the next few weeks.  It should also be noted that the phases of the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) become more of a factor for mid and late winter.

As far as storminess goes, we’ll have to handle those as they come.  The overall pattern screams towards the idea of an active Ohio Valley to interior Northeast storm track as we move forward (continuing deeper into mid and late winter, as well).  That doesn’t mean one or two storms won’t bypass our local region to the south, due to strong, cold high pressure north, but the mean storm track should put areas through the Ohio Valley in the “sweet spot” from a snow perspective throughout the majority of January, and the rest of winter, for that matter.  Depending on the position and strength of the Greenland Block will have a lot to say about things.  Needless to say, storms cutting NW into the central Lakes should be few and far between after the New Year.  Speaking of storms, we have to continue to keep an eye on the second half of next week.  At the time of this discussion, the threat is still beyond the 7-day period, but circle late next week and weekend for the potential of wintry “mischief.”

Permanent link to this article: https://indywx.com/2016/12/29/shift-back-to-a-cold-pattern-awaits-what-about-winter-storm-potential/

Intense Snow Squalls By Evening…

One cold front moved through central Indiana last night with rain showers and a notable wind shift.  A secondary cold front will sweep through the region later this afternoon.  Not only will this deliver reinforcing cold air to wrap up the short work week, but with enough upper level energy and instability, it’ll also serve to ignite some intense snow squalls by evening.  This won’t be a “uniform” snow event, but where the squalls develop, expect rapid reduction in visibility (brief white-out conditions), and a quick coating to 1″ of snow.  Winds will also gust to 40 MPH by evening and overnight.

Here’s an idea of what the radar may look like later this evening:

4p forecast radar

4p forecast radar

6p forecast radar

6p forecast radar

10p forecast radar

10p forecast radar

If you have travel plans this evening into tonight, please allow extra time to reach your destination as these intense snow squalls lead to brief white-outs and quickly create slick travel.  Scattered snow showers will continue into Friday morning, especially across the northern and eastern sections of the state.  Friday will be a cold day as highs top out around 30.

More with an updated 7-day forecast later today!

Permanent link to this article: https://indywx.com/2016/12/29/intense-snow-squalls-by-evening/

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