Category: Long Range Discussion

All Hope’s Lost For Colder Weather Around Thanksgiving? Not So Fast, My Friend…

Our long standing November Outlook was for a chilly first couple days of the month followed by a prolonged period of transitional weather that eventually gave way to more cold around Thanksgiving. Admittedly, we didn’t think the stretch of warmth we’re now exiting would be as significant. While on the surface the longer range doesn’t appear to offer up much hope for significant chill, we continue to keep a close eye on the potential of a more sustained chilly pattern developing by late month.

First, let’s take a look at the latest teleconnections:

As has been the case of late, these are mostly aligned (all with the exception of the EPO briefly) in a manner that will make it tough to drive any sort of sustained chill through the next couple of weeks.

As such, the latest longer range data shows an overall seasonal to warmer than normal pattern continuing as Thanksgiving approaches, centered over the Plains.

This is a bit intriguing as the model is “trying” to see cooler anomalies along the eastern seaboard in the Week 2 timeframe. What’s even more interesting is the higher heights in Canada that develop in the Day 10-15 time frame. Note the dramatic difference between now and then.

That was the basis of our late November forecast (high latitude blocking and subsequent negative AO developing that would force the colder air south). While the teleconnections don’t support that as of yet, one of two things will happen in the coming couple weeks: 1.) the teleconnections will have to adjust or 2.) the model will be incorrect in showing the Canadian ridge developing.

That brings us to the MJO. Just after the 15th, guidance takes things into Phase 2. That phase in November favors colder than normal weather across the eastern 1/3 of the country, including right here on the home front.

Perhaps the longer range European ensemble is beginning to see this and will expand the chill in the coming 10 days, or so. One thing’s for sure, we’ll be here to keep a close eye on the developments and update accordingly. From this distance, I wouldn’t throw in the towel on the potential of a colder pattern developing late month. I know we’re not.

More later this evening, including the daily video update that will take a closer look at rain and embedded thunder tonight.

Permanent link to this article: https://indywx.com/all-hopes-lost-for-colder-weather-around-thanksgiving-not-so-fast-my-friend/

The Beat Goes On (For Now)…

The unseasonable warmth won’t last, at least not to this magnitude, but an overall warmer than average pattern should persist over the upcoming couple of weeks.

The teleconnections (positive AO, positive EPO, negative PNA) are aligned in a manner that will drive the ‘mean’ ridge position across the eastern portion of the country.

Subsequently, the warmth, relative to normal, remains locked in over the East through mid month. Note how similar the GEFS and EPS are between Week 1 and Week 2.

Though we will cool off behind the passage of a cold front next week, we’re still running above normal into Week 2.

We’re not ready to throw in the towel on the idea we could be looking at a more wholesale pattern shift late month. The MJO supports that idea. Note Phase 2 this time of year favors the chill to settle into the East.

It’ll be an interesting test case in what otherwise looks to be a mild to much milder than normal (and quiet) pattern.

Permanent link to this article: https://indywx.com/the-beat-goes-on-for-now/

VIDEO: Next Opportunity For Rain Arrives Tuesday PM; Looking Ahead At The Longer Range…

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2020-2021 IndyWx.com Winter Outlook…

Author: Bill McMillan

Owner & Chief Forecaster- IndyWx.com

Date: 11.01.20

Indianapolis averages 25.5″ of snow per year. To the dismay of many snow lovers across central IN and all across the Ohio Valley, for that matter, we were well below average (9.3″ below normal at IND) last year. Not only have the bulk of the winters over the past decade featured below average snow (couple of outliers, most notably the infamous ’13-’14 winter), but they’ve featured a lack of cold, as well.

Where’s the cold? Overall, the winters of the past decade have run above normal across the Lower 48.

What’s even more impressive is that’s with a few extreme cold winters thrown in the mix. (Just goes to show when warm, we’re running really warm).

When building a seasonal outlook, it’s always important to begin with a look at the current ENSO (El Nino/ Southern Oscillation) state. Typically, things fluctuate between El Nino (warm waters in the equatorial Pacific) or La Nina (cool waters in the equatorial Pacific). This year, we’re looking at a weak-to-moderate La Nina.

https://www.ospo.noaa.gov/Products/ocean/sst/anomaly/

This is forecast to persist through the winter and upcoming spring:

https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/?enso_tab=enso-sst_table

Weak-to-moderate La Nina winters typically produce slightly less than normal snowfall across our neck of the woods, but can also lead to a couple of “big hitters” if the moisture-laden storm systems notorious with Nina winters can combine with the marginally cold air. In most of our analog years, it’s tough to get the cold to “lock in.”

If we simply base our analog package on weak-to-moderate Nina winters, we’ll want to include the following years:

1970-1971

1995-1996

2000-2001

2011-2012

2016-2017

All of these are 1st year weak-to-moderate La Nina winters.

Precipitation Anomalies

Temperature Anomalies

That can serve as a baseline to the general idea, but we want to dig deeper. Recall that we’ve been experimenting with persistent negative AO’s (Arctic Oscillation) in October to try and generate further clues for the upcoming winter. When we add those years into the mix (factoring out any Nino years) and combine the weak-to-moderate 1st year Ninas, this is what we come up with:

Precipitation Anomalies

Temperature Anomalies

It’s this analog package that we’ll ride for the upcoming winter (adding ’60-’61, ’66-’67, ’74-’75, ’81-’82, and ’12-’13 into the mix). We, obviously, will factor in recent climate trends with any year pre-1970.

With all of that said, and before we unveil our official outlook, let’s take a look at what some of the seasonal model data suggests for the upcoming winter (December through February to be more precise).

European

CFSv2

JMA

JAMSTEC

The bulk of the model data above shows a “typical” Nina pattern, but we know each and every winter has it’s own personality…

The wild card this year has to do with blocking, along with MJO amplitude. Both of these are tough to pin point from this distance for the upcoming winter season and will require our attention as we draw closer. That said, the more I research the persistent negative October AO, the more intriguing things become for winter lovers. This is the one item that’s keeping me from “torching” our winter outlook, locally.

Drum roll please: With everything laid out above, our official forecast will call for temperatures to run 1.5° above average at IND in the December through February timeframe with slightly below normal snowfall. Officially, we’ll forecast 20″ of snow at IND (first flake to last flake), but caution that we could have a couple wet, heavy events that make up the majority of that.

Wishing you and yours a blessed holiday season and safe, happy winter!

Permanent link to this article: https://indywx.com/2020-2021-indywx-com-winter-outlook/

VIDEO: Detailed Look At The Upcoming (10) Days And Beyond…

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