Category: AO

Catching Up On A Tuesday Evening And Looking Ahead…

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).

January month-to-date temperature anomalies, courtesy of the Midwestern Regional Climate Center
January month-to-date precipitation anomalies, courtesy of the Midwestern Regional Climate Center

On a broader scale, here’s a look at the current month-to-date temperature anomalies for the Lower 48 as a whole:

January Lower 48 month-to-date ‘mean’ temperature anomalies, courtesy of weathermodels.com

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! 🙂

Permanent link to this article: https://indywx.com/catching-up-on-a-tuesday-evening-and-looking-ahead/

Important To Know What Lever To Pull And When…

As another year comes to a close and the winter pattern begins to “mature,” we thought we’d do a little rambling…

This evening’s rambles have to do with the variety of “drivers” that at times like to take control of our weather pattern. You hear us use terms like the MJO, EPO, AO, PNA, and NAO (amongst others) often, but at times, these various pattern drivers can have more impact than others, and at varied times of the year.

Traditionally, if the MJO (Madden Julian Oscillation) is highly amplified, that’s going to serve as the basis of our medium or longer range forecasts. However, if the MJO is in the null phase, other teleconnections can take control of the wheel. Sea-surface temperature configuration can give hints to the way these elements may behave during the season(s) ahead, but we caution each respective season takes on a flavor unique to it’s own. That’s what makes this business so fun, challenging, and, at times, frustrating. 🙂

It’s also important to understand when the ingredients noted above have the greatest impact on our immediate weather. We love to lean more heavily towards the NAO and AO mid-to-late winter into the spring, for instance. Case in point, a negative EPO and positive PNA can quickly trump a positive AO/ NAO this time of year, and vice-versa.

In the event you didn’t have a chance to see it Sunday, we released our January Outlook. We have a very stormy month outlined that includes cold “overwhelming” things as the month progresses. A lot of this has to do with the fact we think we see a “shake-up” with the MJO out of the warm phases and into the traditional cold phases of 8,1, and 2 taking shape during the 2nd half of the month. Additionally, we continue to believe the favorable north Pacific sea surface temperature configuration (for a cold Great Lakes and OHV) will begin to force the negative EPO/ positive PNA.

The NEW European Weeklies show the transitional time of things through the 1st half of the month, but note the building more persistent NW NA ridge during the 2nd half of the month and corresponding reflection of an eastern trough. Should the MJO be heading into Phase 8 around this time frame (and we think it will), this trough will likely correct stronger in future updates for late month.

The model sees the stormy time of things through the month and into February. (Important to note that even “warm” months this time of year can also feature above normal snow. Just see this December- nearly an inch above normal for the month). As things stand now, we see multiple opportunities for snow as January gets underway, including Saturday PM, and again Tuesday night into Wednesday.

Make it a great evening! We’ll be back early in the morning with a fresh video update.

Permanent link to this article: https://indywx.com/important-to-know-what-lever-to-pull-and-when/

Heavy Snow Tonight: Timing Out “Part 2” Monday And Looking Closer At The Late Month Pattern…

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VIDEO: 2-Part Storm Sunday Evening-Tuesday Morning; Active Times Through The Holiday Season…

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Pattern Evolution Through Late October…

The teleconnections are aligning in a manner that favors a colder than average period of weather by late-October standards. Note the PNA trend positive while the EPO heads negative. The AO and NAO also follow suit.

The sum of all of the above should feature a predominant western ridge for late month with a persistent eastern trough- at times deeper than others.

Add in the fact that the MJO is anticipated to swing into Phase 2 and this further serves to increase confidence in the colder shift.

The models are focusing in on the colder close to the month and though specifics will continue to vary from run-to-run, the primary message that we want to convey is to expect a colder than average 2nd half of the month with an active storm track. As pops of more “winter-like” air get involved behind one or two of the late month storms, pre-Halloween flakes may fly across a portion of the Ohio Valley.

Days 3-8
Days 8-13
Days 10-15

Given the pattern progression and anticipated teleconnection states, we think it’s wise to ensure the kiddos have a warm Halloween costume this year!

Permanent link to this article: https://indywx.com/pattern-evolution-through-late-october/