Dec 10
Tonight we look at the pattern evolution into early January, as well as take a deeper dive into 2 systems of note: heavy rain late Friday night into Saturday and…
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Nov 22
This morning is once again reminding us that we can deal with wintry “issues” at times even in the midst of an overall mild pattern. As we move down the road, it sure appears as if additional opportunities for wintry weather will present themselves as the pattern evolves towards more of a traditional regime to support such.
More specifically, we’re targeting the period between 11/30 and 12/10. Though still not a “textbook” pattern, the PNA is trending more positive with each run. This favors as eastern trough (example below).
Note how the upper pattern evolves in the coming couple of weeks:
You might be asking yourself, “what would take this pattern to lock-in and become more textbook?” We need the two positives (initially over Saskatchewan and Manitoba to “connect” with the one in the northwestern Atlantic). As it is, we do note the heights continue to build and push towards Greenland. I’m not sure we can pull it off, but the evolution towards a strong PNA can force the issue and eventually lead to a negative AO. Regardless of whether or not we get to that point, which would lead to a more long lasting colder/ stormy regime, I think we’ll have a minimum of 2 opportunities for eastern wintry “fun and games” during the aforementioned period above.
As we get into Week 2 (11/29-12/4), note how the pattern has the look of an active subtropical jet as the “horseshoe” block tries to get established over the top. This is likely still not an overly cold pattern, but one plenty capable of additional wintry fun, even with marginally cold air.
Stay tuned. The closer we get, the more specific we can be regarding the storms. From this distance, if I’m a fan of winter weather, you have to like where you’re sitting as we open up meteorological winter.
Permanent link to this article: https://indywx.com/troubling-pattern-to-close-november-open-december/
Nov 21
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Oct 06
October has opened on quite a chilly note across not only central Indiana, but a good chunk of the eastern half of the country. Officially, Indianapolis is running 8.4° below average, month-to-date.
While warming will occur in the upcoming 7-day period, there are already seeds being planted for the return of unseasonably chilly conditions after this transitional warmth.
The pattern will take on signs that you’d expect from a positive PNA and trending negative EPO. That will pull the chill back into the east and we may just may trend wetter during the mid and late month period, as a series of cold fronts sweep through the region (fingers crossed).
The purpose of this post is to focus on the predominantly negative Arctic Oscillation (or AO) and what, if anything, we can learn for the upcoming winter. Note the AO continues a negative look over the upcoming couple weeks (it’s been negative so far this month, as well).
The combination of the persistent negative AO so far this month, along with what’s forecasted over the coming few weeks, got us interested to see what kind of patterns occurred during the following winter (Dec. through Feb.). We went back and looked at all October with a negative AO of 1, or more, since 1960 and this is what the analogs produced:
There’s obviously a lot of other ingredients we’ll factor into our winter outlook this year (per usual), but this is another interesting case study in front of us, especially with so many climate models blow torching the upcoming winter.
Our complete annual winter outlook will be online Sunday, November 1st.
Permanent link to this article: https://indywx.com/what-can-we-learn-from-a-persistent-negative-october-ao-for-the-upcoming-winter/
Jan 21
January is flying by! With only 10 days left in the month, Indianapolis is running a whopping 8.2° above normal along with more than 3″ above normal in the precipitation department (unfortunately for snow lovers, this excess moisture has fallen primarily as rain, as IND is running a deficit of 5.2″ in the snowfall department).
On a broader scale, here’s a look at the current month-to-date temperature anomalies for the Lower 48 as a whole:
As a refresher, our January forecast looked like this:
The baseline of this thinking had to do with the idea we had that the MJO would roll out of the warm phases (5 and 6) and strongly into the colder phases after mid-month. Secondly, the other driver was the thought that the current SST configuration in the north Pacific would “force” a negative EPO as the winter season matured.
While the MJO did, indeed, rumble out of the warmer phases just after mid-month, the EPO has not cooperated. Furthermore, instead of the MJO tracking into Phases 8, 1, and 2, it appears it wants to go into the “null” phase to figure out its ultimate destination for the 2nd half of winter (this will be key with Feb. and March). While this doesn’t necessarily support warmth, it doesn’t offer enough ammo to fight the warm signal from the strongly positive EPO.
Now that we’re beginning to turn the page to the 2nd half of winter, there are other items to begin paying closer attention to. In addition to the EPO and MJO, some of these features include the AO, NAO, and PNA. With that said, to drive more of a consistent colder than normal theme, we need to get the EPO at least into the neutral range as some of the other ingredients noted above transition into more favorable colder phases. With a strongly positive EPO, it’ll be tough to sustain well below average temperatures.
With all of that said, all hope is not lost for winter lovers. Climatology speaking, we’re in the coldest time of the year. Even in “marginally” cold patterns, or even “warm” patterns this time of year, wintry issues can create headaches. Secondly, it’s worth paying close attention to the MJO over the next couple of weeks as some of the data wants to take things out of the null phase and transition towards the traditionally colder phases of 8, 1, 2, and 3.
As it is, the next couple of weeks should present a fairly active storm track across the region. In the face of what should truly be a “torch” pattern, the saving grace (at least for fans of winter weather) has to do with the strong Hudson Bay ridge and tendency this kind of pattern has to force stormy times underneath. While far from a “slam dunk,” these kind of patterns can produce- even in the face of a strong positive EPO.
If you had to choose, would you rather have a bitterly cold and dry regime or seasonably mild with at least being on the playing field for wintry mischief over the next couple of weeks?
More in the AM, friends. Make it a relaxing evening! 
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