Category: Arctic Cold

Oct 06

What Can We Learn From A Persistent Negative October AO For The Upcoming Winter?

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.

A transitional period of warmth will engulf the region over the better part of the upcoming 7-days.

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/

Sep 08

2 Sides To Every Storm…

An early taste of winter is descending on the Rockies today (the town of Breckenridge camera will be fun to check in on from time to time over the next 24 hours). Places, such as Denver, that were in the 90s yesterday will fall into the 20s and 30s today with snow.

Note the big spread in temperatures across the country this morning and corresponding 24 hour temperature change:

We’ll remain on the mostly dry and warm side of this event until the weekend.

Once the storm system lifts northeast and gets close enough to impact our region, it’ll be in a much weaker state. Scattered showers and thunder are possible over the weekend, but widespread significant rainfall isn’t expected.

After heavy rains fell across north-central Indiana Monday, a much drier theme can be expected throughout the next several days. A widely scattered shower or thunderstorm is possible before Saturday, but most should remain rain-free. Even as the storm system draws closer, weekend rainfall should average only between 0.25″ and 0.50″ for most.

Cooler air (nothing to the extent or magnitude of what our friends out west are seeing) will filter in here late weekend and early next week. Lows into the 50s can be expected with a couple of days of highs in the 70s.

Permanent link to this article: https://indywx.com/2-sides-to-every-storm/

May 12

Major Flip On Deck; Discussing Longevity…

Indianapolis is running a whopping 8° below normal month-to-date. We’ve set new daily and all-time records already this month for the cold. Note the vast nature of this May chill.

If you’re not a fan of the late season chill, hang in there, as a major flip in the pattern awaits. We alluded to this possibility in our May Outlook and it continues to look like a rather abrupt change is a couple of days away. While we’re dealing with frost this morning in spots across east-central Indiana, it’s looking more and more likely that the first true summer-like surge of air for the season arrives Thursday into the weekend. Warmth will be accompanied by a significant uptick in humidity levels.

The Week 2 period looks warmest, relative to average, and should feature at least a couple of days with highs approaching the 85°-90° mark.

While most data maintains a warmer pattern to close the month, there are a couple of items to pay close attention to as we try and understand the longevity of said warmth.

  1. The MJO is forecast to remain “bottled up” in the wheelhouse through the next couple of weeks. Thereafter, there are indications that the MJO might become more amplified and it’ll be important to keep an eye on what phase(s) it’ll move through as we get set to close May/ open June.

2. The PNA is forecast to take a negative dip which supports the coming flip to warm. However, recent ensemble data is bullish on a move towards a positive (some data shows even strongly so) state around or just after Memorial Day. This would suggest the window of warmth may be limited in duration. Simply based on looking at the chart below, one could build a case for a cool open to meteorological summer.

Finally, on the precipitation front, a wetter pattern is anticipated to accompany the warm change, but longer range data points towards this being only a temporary wetter regime. In fact, recent models are beginning to agree on a dry close to May/ open to June.

Much more later!

Permanent link to this article: https://indywx.com/major-flip-on-deck-discussing-longevity/

May 11

From One Extreme To The Other…

The work week will get off to the same unusually chilly start we’ve begun to grow accustomed to. Additional frost and freeze threats are present Tuesday and Wednesday mornings if skies can clear (big if there). However, significant changes loom as we flip the page to the second half of the work week and longer term indications suggest we’re well on our way to a true summer-like feel by week 2.

Note how bullish the European ensemble is regarding the significant pattern flip over the next couple weeks.

A lot of this is driven by a change in the EPO. This is the kind of pattern that stands to at least threaten sending high temperatures soaring to between 85°-90° between Week 2 and month’s end. Talk about a contrast from the late winter and early spring-like chill to open the month!

The transition in the pattern is likely to be met with a much more active storm track through the area beginning midweek. There will be a threat of locally heavy rain and stronger storms that will continue at times into the weekend and beyond into next week, as well.

For a month that’s gotten off to a dry start, we’ll likely recover quickly with this wetter regime that accompanies the flip to warm.

We continue to believe most central Indiana neighborhoods will see between 1.75”-2.25” late week into the weekend, but there will be locally heavier amounts. The majority of data also suggests a corridor of wetter than normal conditions sets up from the Plains into the northern Ohio Valley/ Great Lakes into Week 2.

Stay tuned.

Permanent link to this article: https://indywx.com/from-one-extreme-to-the-other/

May 08

VIDEO: Stage Set For Record Cold Saturday AM; Updated Long Range Thoughts Towards Memorial Day Weekend…

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Permanent link to this article: https://indywx.com/video-stage-set-for-record-cold-saturday-am-updated-long-range-thoughts-towards-memorial-day-weekend/