Category: Ensemble Discussion

For Now, It’s A Tale Of The MJO And PNA…

Updated 12.26.21 @ 7:38a

Over the past couple of weeks, several of the teleconnections (EPO, AO, and NAO) have been in favorable phases for cold air to take up residence in our neck of the woods. However the combination of Phase 6 of the MJO (image 1 below) and a deeply negative PNA (image 2 below) have fought off any sustained or significant cold.

As we look ahead, there are changes in both of these critical pattern drivers. First, the MJO looks to continue progressing deeper into Phase 7. This is significant as today, though while officially in 7, we’re really still feeling the effects of 6. There’s a lean from guidance that Phase 8 is also within reach as we get towards mid-January, but we won’t get greedy. 🙂 If we can at least get deeper into 7, that will greatly lessen the influence of the warmth that continues to linger with Phase 6.

Note how the trough likes to settle into the eastern portion of the country during these phases.

That then brings us to the PNA. Guidance is trending things closer to neutral towards Day 10. This is significant as it would allow the southeastern ridge to at least get beaten down (not totally squashed as long as we remain negative), but certainly enough to allow the cold currently bottled up out west to bleed east.

This can be illustrated best by looking at the 500mb pattern evolution over the next couple weeks per the latest GFS ensemble below.

To summarize, while we still have warm days ahead of us, there does at least appear to be a couple trends heading in the right direction for all of those longing for colder and potentially more wintry times as we get past the new year.

Hang in there you snow lovers. It’s far too early to jump off the ship…

Permanent link to this article: https://indywx.com/2021/12/26/for-now-its-a-tale-of-the-mjo-and-pna/

VIDEO: Busy Short-Term Pattern; Drivers Behind The Regime Into Mid-January…

Updated 12.24.21 @ 7:35a

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Permanent link to this article: https://indywx.com/2021/12/24/video-busy-short-term-pattern-drivers-behind-the-regime-into-mid-january/

VIDEO: Very Active Pattern To Close Out The Year…

Updated 12.23.21 @ 5:32a

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The Beat Goes On And On And On…

Updated 12.22.21 @ 7:45a

Average temperatures on the 22nd of December include a high of 38.6° and a low of 24.7°. We’ll be slightly under those levels today in what can be termed an “island” of cold in a “sea” of warmth. In fact, the month is running close to 7° above normal thus far.

Highs today will top out in the lower to middle 30s for most of central Indiana.
December 2021 has featured widespread above normal temperatures, centered across the s-central Plains into the TN and OH Valleys.

As we look towards the all-important Christmas forecast, quiet weather will carry us into Christmas Eve. That’s when we’ll tighten the pressure gradient and build in southwest gusts of 30 to 40 MPH.

Those southwesterly winds will transport a few scattered light showers into the region Christmas Eve evening into Christmas Day, but these won’t be a big deal. “Scattered” and “light” are the key words.

What will be a big deal are the temperatures. In fact, latest guidance is pointing towards a new record high on Christmas Day. Should we see any sunshine get into the mix, this will be easily achievable.

Modeled high temperatures on Christmas afternoon.
A look at Christmas Day records in Indianapolis, IN

Thereafter, the same general pattern remains intact, locally (- PNA ridge), but notice the cold bleeding into the West between Christmas and New Year’s. Does this eventually make progress east? We think so as we get into January…

Permanent link to this article: https://indywx.com/2021/12/22/the-beat-goes-on-and-on-and-on/

VIDEO: Sunshine Prevails For Now; Tracking Light Rain By Christmas Eve…

Updated 12.21.21 @ 8a

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VIDEO: Detailed Look At The Pattern To Close Out The Year And As We Head Into January; Shift to Cold Still On The Table?

Updated 12.19.21 @ 11a

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Long-Winded Discussion Diving Into The Pattern As We Welcome In 2022…

Updated 12.16.21 @ 6:07p

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Severe Weather Update; Wholesale Pattern Change On Deck In Time For The Holidays…

Updated 12.09.21 @ 5:30p

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VIDEO: Light Snow Develops This Afternoon Across Southern IN; Record Warmth Next Week?

Updated 12.07.21 @ 7:30a

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Permanent link to this article: https://indywx.com/2021/12/07/video-light-snow-develops-this-afternoon-across-southern-in-record-warmth-next-week/

VIDEO: Unseasonably Mild And Quiet For Now, But Are Changes Lurking?

Updated 12.02.21 @ 6:40p

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