Category: NAO

Feb 16

Meteorological Spring A Couple Weeks Away, But Trends Suggest Winter’s Not Done…

With the exception of a rain maker blowing through the region Monday evening into Tuesday, we’re heading into a relatively quiet weather pattern for the upcoming 7-8 days. A couple of days of well below average temperatures will follow Tuesday’s cold front before weekend moderation takes place. With the shift in the pattern (albeit likely only for a brief period of time), we thought we’d look ahead to what may loom to close February and head into March.

As we’ve discussed in the past, the EPO and MJO are the keys to the pattern, and will continue to be through March. Some of the recent trends with both features would suggest cold is going to fight back as we head into late Feb and early March (spike positive in the EPO also boosts our confidence the pattern will warm over the weekend and into early parts of Week 2). This would likely be met with a return of an active storm track through our neck of the woods.

Both the GEFS and EPS paint a developing negative EPO as we close the month and welcome March. Secondly, the MJO is looking more and more like it’ll move out of the traditional winter warm phases and towards a much colder Phase 8. Collectively, these features should give pause to anyone thinking the kick-off to meteorological spring will be met with dry, warm weather. In reality, the opposite would more than likely result- stormy with colder than normal weather.

This is also the time we begin leaning more heavily on the influence a negative NAO can have on the pattern. Should this teleconnection get into the negative territory in March, then we’d be talking about a potential colder pattern lasting for 10-14 days towards one that would reload to result in colder, wintry conditions lasting into April. While not there yet, it’s certainly worth keeping an eye on in the coming days and weeks.

Permanent link to this article: https://indywx.com/meteorological-spring-a-couple-weeks-away-but-trends-suggest-winters-not-done/

Jan 21

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/

Jan 16

Wintry Mix Tomorrow Evening; Fresh Long Range Fun…

Friday will dawn dry, but the mid and high level cloud canopy will be a sign of things to come. These clouds will lower and thicken through the day and eventually give way to a wintry mix by evening. While there may initially be a period of snow (especially north of Indianapolis), the majority of the “overrunning” precipitation should fall as a mixture of sleet and freezing rain. In and around Indianapolis and points north, a light “glaze” of ice is possible Friday evening of up to .10″ (after the possibility of a coating of snow).

Dry air will likely have to be overcome at first, but a burst of snow is possible into the city around 5p to 6p before the transition over to the sleet and freezing rain mixture. Eventually, the icy mixture will transition to a cold rain prior to sunrise Saturday.

MUCH colder air will pour into the state Saturday evening with temperatures falling into the 10s prior to midnight Sunday morning and wind chills into the single digits.

As we look longer term, we don’t see any reason to alter our ongoing thoughts of a colder pattern taking hold, overall, over the upcoming 10-14 day period (and likely into the first half of Feb.). We’ve covered our reasoning in previous posts (Phase 7 of the MJO, positive PNA, neutral EPO, etc.). What’s interesting to note is the rather stark difference in the handling of the EPO between the negative GEFS and positive EPS. The likely end result will be somewhere in between; hence our neutral EPO forecast. At the end of the day, it’s really not the EPO, PNA, or NAO that will drive the mean pattern, but the MJO. And with that said, Phase 7 of the MJO features a cold, stormy look.

The high latitude blocking screams for an active storm track across our neck of the woods (as does the slightly positive PNA and neutral EPO). Sure enough, the latest modeling is going towards this stormy look (active southern stream) in the medium to long range period.

A great mentor once taught me to always be leery of ridges over Hudson Bay in the winter time. Time and time again, this pattern setup results in fairly widespread winter storm events through the Lower 48 and we think there is increased potential in this sometime during the Jan. 25-31 time period. While there’s no way to be specific, just keep a mental note in the back of your mind for this threat.

In closing, a review of the latest JMA Weeklies shows a significantly different pattern than what we’ve grown accustomed to as of late taking up residence through the bulk of the upcoming 3-4 weeks. Given the above, it would be tough to argue this look…

Week 1
Week 2
Weeks 3-4

Fresh video update will hit in the AM with new thoughts around tomorrow evening’s winter weather maker.

Permanent link to this article: https://indywx.com/wintry-mix-tomorrow-evening-fresh-long-range-fun/

Dec 30

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/

Dec 15

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

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Permanent link to this article: https://indywx.com/heavy-snow-tonight-timing-out-part-2-monday-and-looking-closer-at-the-late-month-pattern/