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Category: PNA
Permanent link to this article: https://indywx.com/changing-weather-to-open-the-work-week/
Jan 30
Bet On The Cold…
During wholesale pattern transitions, operational data will struggle at times, including some wild run-to-run swings. Earlier this week, the European wanted to put early next week in the lower 50s. At the same time, the GFS suggested lower single digits. Precisely, it was a difference of 46° between the two models for a high?! 🙂
We note the teleconnections (in particular, the EPO) are aligning in a manner conducive for widespread cold.
The GEFS might be a bit quick on dropping the arctic hammer, but the consistency of the model is impressive. Meanwhile, the European (even it’s ensemble data) has been much less consistent and has really been struggling the past couple of winters, overall, as a whole.
While we can argue as to just how cold it’ll get through the early part of February, the overwhelming message is that a prolonged colder than normal pattern will develop during this time period.
Let’s also keep in mind that the initial cold onslaught is coming in the face of the MJO still rumbling through the warm phases. We note the European is consistently having to correct towards a more “amped up” MJO- swinging into the cold phases as we approach mid-month. And it’s mid-February that continues to have us concerned for the potential of truly nasty, severe cold.
As for snow, it’ll come in this pattern. Again, don’t get caught up in the operational output, but understand that the pattern over the upcoming 7-10 days favors numerous fast-moving snow systems. While most of these will be light, we’ll have to keep a close eye on things as the potential exists for one of these waves to spin up a moderate event.
As we look ahead to Week 2, the potential is there for a more widespread significant phased interior threat prior to the dumping of the bitterly cold air for mid-month.
As it is, both the GEFS and EPS “mean” paint a bullish signal for piling snow up over the next couple weeks…
Permanent link to this article: https://indywx.com/bet-on-the-cold/
Jan 28
Transition Begins Back To A Prolonged, Sustained Wintry Pattern…
The January “thaw” has taken hold the past 7-10 days.
Despite the milder air over the past week, January, as a whole, is still running 4° below average at Indianapolis- a byproduct of just how frigid the first half of the month was.
While the January thaw has been nice, times are changing and winter sure seems to be reloading for a very active second half.
Initially, we think it’s the storminess that will be most impressive as a “fight” develops between resistance from southern ridging and a new mean trough pushing southeast. The end result should be multiple snow and ice makers from the southern Plains into the Ohio Valley and northeast over the upcoming couple of weeks.
Once we get a snowpack laid down, arctic highs oozing southeast will likely lead to bitterly cold air. Recall our expectation for this pattern to yield at least (1) night of double-digit below zero lows, but it’s more towards mid-month that we think the severe cold takes hold.
Teleconnections are lining up and in overall agreement of cold, wintry times returning.
The Madden-Julian Oscillation (MJO) is forecast to rotate into the colder phase 8 as we rumble from early to mid February. Given the amplitude of the MJO, it should continue to rumble right through the cold phases of 1,2, and 3.
All of these moving pieces that lead up to extended periods of cold, wintry conditions are part of a bigger outcome low solar, easterly QBO winters deal up. What we should experience with this setup is a 6-7 week period of wintry conditions, including times of severe cold. It appears to be a snowier version of what we went through late-December through mid-January. Hang in there, spring will come…eventually.
Permanent link to this article: https://indywx.com/transition-begins-back-to-a-prolonged-sustained-wintry-pattern/
Dec 16
EPO-PNA Battle
One of the many ingredients we like to throw into the mixing bowl when developing our medium range forecast is the teleconnection breakdown. Many times, the various teleconnections play into themselves and agree, but, at times, conflicting signals lead to a fight. At any given time, one or the other “big boy” teleconnections can take control of the pattern and simply overwhelm. As things stand now, it appears as if the two teleconnections trying to control are the EPO (Eastern Pacific Oscillation) and PNA (Pacific North America pattern), highlighted below.
As we’d expect, as these two fight it out, a battle will ensue across the central and eventually eastern portion of the country. The negative EPO is a widespread cold pattern, while a negative PNA favors south-central and southeastern ridging (a warmer pattern).
When we look at the latest ensemble data, we see this battle playing out within the modeling.
Eventually, we expect the deeply negative EPO to take control and overwhelm the pattern with cold. However, as this transition of power takes place, the negative PNA won’t go down without a fight and will likely play a role in the weather leading up to Christmas.
The negative PNA suggests we need to remain on guard for the potential of an interior snow/ ice event around Christmas. As we’ve been mentioning, from this distance there’s no way to say whether this is an impactful wintry event for our region, or just to our north or south. We should be able to become more detailed within the next few days…
Permanent link to this article: https://indywx.com/epo-pna-battle/
Dec 01
VIDEO: Winter Set To Lock In…
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Permanent link to this article: https://indywx.com/video-winter-set-to-lock-in/