Category: AO

Feb 12

We Have The Storms; Time To Add The Cold…

Over the past month, a widespread portion of the Ohio Valley, including central Indiana, is running close to 200% of average in the precipitation department. There’s no wonder flooding issues have resulted in spots- especially across the lower OHV region.

As we look ahead, the active storm track will persist, but there will be one key missing ingredient from the better part of the past couple of weeks and that’s more in the way of sustained cold. After reviewing some of the latest data, there’s no reason to change our ongoing idea of the transitional period (in the midst of that now) giving way towards one that will feature more in the way of “lock and load” cold in that 2.18 through 3.10 time period. We expect this period will run well below average in the temperature department and above average in the snowfall category. Snow removal clients, we recommend gearing up for a busy time of things over the upcoming few weeks.

The basis of this idea initially focused squarely on the MJO and the fact that modeling was keying in on things swinging into the favorable cold phases of 8, 1, and 2.

Taken at face value, this would be the corresponding upper air look in those respective phases:

Phase 8 (coldest)

Phase 1

Phase 2

Phase 3 (cold begins to “back into the west and there’s at least a hint of the SE ridge returning)

As most longtime followers know, we put more stock into the NAO state during the latter winter and spring months, as this teleconnection can “trump” others during this time frame. We notice the NAO is forecast to trend negative as we progress through the back half of February.

A negative NAO will result in widespread cold this time of year:

After remaining strongly positive for the past couple of weeks, the AO is forecast to plunge negative as we progress through the remainder of February. Again, this increases confidence on a return of more sustained and significant cold potential.

It should also be pointed out that the active pattern should continue, especially considering the southeast ridge should put up some resistance over the upcoming couple of weeks. The latest ensemble products would agree in the mean upper air pattern:

With colder air overwhelming the pattern, more of these storms will be capable of producing impactful wintry precipitation over the upcoming few weeks. After storms grab the headline, attention will shift to the possibility of another significant arctic blast before the end of the month.

In the more immediate term, we continue to keep close tabs on the following dates for the potential of snow and/ or ice:

I. Friday night, 2/15 and Saturday, 2/16- southern half of Indiana

II. Sunday, 2/17

III. Tuesday night, 2/19 and Wednesday, 2/20

Permanent link to this article: https://indywx.com/we-have-the-storms-time-to-add-the-cold/

Feb 10

All-Access Sunday Evening Video Update…

Another busy weather week is dialed up for central Indiana, including flooding and accumulating snow. We also look ahead to late month and early March…

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Permanent link to this article: https://indywx.com/all-access-sunday-evening-video-update/

Feb 08

Long Range Discussion: Window Opens For A Return Of Winter, But This Isn’t Last Year…

The stage is set for winter’s return. With that said, the upcoming week will likely feature a “transitional” time of things before winter returns with more authority during the 2/18 through 3/10 time period.

While the positive AO will continue to be heard from in the more immediate term (forcing the active storm track into the Ohio Valley and Great Lakes), this should eventually give way to a negative AO by mid and late month. Factor in a Phase 8 of the MJO and developing negative NAO and winter weather lovers will likely have a 2-3 week period of “fun and games,” including the potential of a couple significant events, along with well below normal cold late February and early March.

That said, this isn’t last year. Recall it was around this time that we were initially “faked out” by a wintry February when in all actuality it was a case of delayed, but not denied, with the worst of winter (relative to average, and in the means from a snow perspective) occurring in March and April. There are growing indications that we should actually have a spring this year, but more on that at a later time. 🙂

Let’s take a look at some of the latest long range modeling, starting with teleconnections first (always the basis of a long range forecast).

Simply put, the GEFS teleconnections line up for a return of colder than normal conditions during the middle to latter part of February. We love to see the agreement in the teleconnection states (trending negative AO (image 1) and NAO (image 3) and trending positive PNA (image 2)).

The latest European Weeklies would also agree. Note the strongly positive AO (image 1 below) at present dips negative during the 2nd half of February.

The European Weeklies like the idea of the PNA at least getting to neutral late month into early March.

  • Also of importance is what the Weeklies do with both teleconnections by mid-March (this would support a warmer pattern, overall).
  • Since we’re talking about the European Weeklies, while we can’t show the model output itself, it should be noted the model does deliver cold back into the region in rather widespread fashion during the last couple of weeks of February and into the first week of March.

Other model data paints a similar picture as noted below between the GEFS and CFSv2 Weeklies:

Days 5–15
Days 15-25
Days 20-30

But, like other data would suggest, the CFSv2 is also in agreement that as early March gives way to the middle of the month, warmer times loom…

Days 30-40

(In the event you missed it this morning, we reviewed the updated JMA Weeklies earlier here).

The latest MJO update continues to back up the idea of colder times returning mid and late February, continuing into early March, as noted below. Remember, this time of year, Phases 8 and 1 are colder phases for our neck of the woods.

To summarize, we expect this upcoming week to begin the transition back towards an overall colder and increasingly busy time of things from a wintry perspective. Those will snow removal interests should anticipate above average snowfall during the 2/18 through 3/10 time frame. The aforementioned period also should run colder than average, as well. However, those tired of winter, hang in there- hope is on the horizon once to mid-March and we should actually enjoy a pleasant spring this year after missing out in ’18!

Permanent link to this article: https://indywx.com/long-range-discussion-window-opens-for-a-return-of-winter-but-this-isnt-last-year/

Feb 07

Thursday Afternoon All-Access Video Update…

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Feb 07

Dissecting Today’s Severe Potential; Winter Returns & Looking More In-depth At The New JMA Weeklies…

The Storm Prediction Center (SPC) has significantly expanded the “slight risk” area to include a large portions of the state.


While a fresh batch of heavy rain will move into central Indiana later this morning (another 1″ to 2″ is a good bet for most communities), the focus shifts to a window where severe thunderstorms will be possible during the early to mid afternoon.

A warm front will lift north through central IN late morning and this will allow relatively warm and moist air to briefly surge as far north as a Logansport to Fort Wayne line.

Note dew points will spike to 60 to 63 degrees over much of central and eastern IN this afternoon.

It’s during the 1p to 5p window when we’re most concerned for the chance of a few severe thunderstorms ahead of the cold front. Damaging winds are of greatest concern, but anytime you have a warm front hanging around central Indiana with these kinds of setups, the potential of a tornado is in the back of your mind. I don’t foresee this being a major tornado outbreak whatsoever, but parameters do suggest the chance of a quick spin-up tornado is present, as well during this timeframe.

The cold front will crash into Indianapolis between 4p and 5p and you’ll certainly know it.

Strong and gusty northwest winds will blow sharply cold air into the region this evening and tonight. In fact, highs in the lower to middle 60s this afternoon will be into the 20s before midnight. Lows Friday morning will fall into the 10s and highs Friday will only top out in the lower 20s with wind chill values in the single digits most of the day.

After a dry open to the weekend, we continue to monitor the potential of a light wintry event Sunday into early Monday. This doesn’t appear to be a big deal, but the chance is there for an inch or two of snow for portions of the central and northern Ohio Valley during this timeframe.

Additional challenges await early and mid next week, but we’ll save those for updates later this afternoon or evening.

JMA Weeklies

The updated JMA Weeklies are in and in short suggest the southeast ridge continues to put up a fight over the next couple of weeks before getting “squashed” in the Weeks 3-4 timeframe.

This is in line with our thinking of the “transitional” period beginning this upcoming week. We think cold will begin to “push,” but isn’t ready to lock-in as of yet. There will be cold readily available to present more of a wintry potential with storms that track through the region when compared to this week, but we think it’s the period from 2/17 through early March that has the capability of featuring more sustained cold.

That’s a strong signal being painted by the JMA Weeklies in the Weeks 3-4 timeframe for widespread cold. Given that the MJO is forecast to swing into Phase 8 by this timeframe, along with the NAO/ AO looking to dip negative, the widespread cold look is a good idea to us during this particular time period.

Permanent link to this article: https://indywx.com/dissecting-todays-severe-potential-winter-returns-looking-more-in-depth-at-the-new-jma-weeklies/