Category: PNA

Reasons For (And Against) The “Big One” Next Week…

Updated 02.10.21 @ 6:23p

Before we look ahead, snow continues to fall across most of central Indiana. So far, immediate downtown Indy has avoided significant snow, but other areas are approaching 1″ to 2″ already as of this post. We continue to believe another band of snow will organize during the overnight into the predawn hours across central Indiana (especially along and north of the I-70 corridor). Given how cold it’s been as of late, even the lightest snow is creating havoc on area roadways. As winds become gusty, blowing and drifting issues will remain into the day Thursday.

As we look ahead, this pattern remains nothing short of remarkable. Feb. 5th (last Friday at 6p) was the last time Indianapolis was above the freezing mark. As we look ahead, we’re likely talking about another 12 days below freezing (if not longer). The “moderation” that some models are hinting at after that time frame isn’t something I’d label as high confidence at this point. That’s rare territory for central Indiana- even during some of the infamous cold winters of the “good ole days.” There’s also already been a fair share of snow events in this pattern. Sure the big one hasn’t hit (yet), but many across the state are getting used to clearing snow off the sidewalk and driveway on a daily basis. Not counting today’s snow, Indianapolis, officially, sits at 2.3″ month-to-date. Areas downstate received as much as half a foot (or more) earlier this week. As we look ahead, there’s a lot more white gold where that came from. (Keep in mind, the “average” snow total during the month of February in Indianapolis is 6.5″).

A fresh intrusion of arctic air will arrive just in time for the weekend. We’re looking at a mostly dry stretch of weather through the weekend, with the exception of some light snow prospects Saturday. Again, given how cold it’s been, even these light snow events will likely create travel trouble.

The coldest morning appears to be Sunday with lows falling to between 3° and 6° below zero. Wind chill values will approach 20° below zero, or worse, in spots.

By this time, all eyes will be on the developing storm system in the northwest Gulf of Mexico. There’s already been a great deal of chatter about this storm and that will only continue to ramp up as we move forward. Given the overall pattern and model consensus at this juncture, there’s plenty reason to believe the Ohio Valley, including central Indiana, is in store for a significant winter storm early next week.

With that said, nothing is a lock in this business. While the negative PNA (image 1 below) argues for the southeast ridge to “flex” it’s muscle and lead to a more inland track, the fact arctic air will be pressing southeast (image 2 below) does at least raise an eyebrow for potential shifts southeast in time over the next couple of days. It’s another fascinating meteorological battle we’ll have the pleasure to watch unfold in real time.

As it sits right now, we favor a storm track that will be far enough west to put central Indiana in play for potentially significant wintry precipitation (far too early to throw numbers out). The early call is for surface low to move out of the northwest Gulf and track west of the mountains before a secondary low take over along the Mid-Atlantic and moves northeast off the New England coast.

If this wasn’t enough, another storm system likely follows later next week that could also produce additional wintry “goods.”

Will every storm produce in your backyard? Negative. That said, when we get to March 1st, central Indiana winter weather fans are likely to look back on February 2021 as a truly special ride.

I suppose time will tell…

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VIDEO: Cold, Snowy Pattern Locking In For The Foreseeable Future…

Updated: 02.08.21 @ 5:35p

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VIDEO: Tracking Multiple Winter Weather Makers Over The Upcoming 7-10 Days…

Updated 02.05.21 @ 4:19p

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Buckle In…

Updated 02.05.21 @ 7:18a

Where to begin?! Simply put, the pattern over the next 2 weeks is a winter weather lover’s dream setup. Does that mean central Indiana has to “cash in” on every event? Negative. In fact, by next weekend, we believe the Deep South will even get in on the wintry fun (outside of the higher elevations that have been doing quite well this year). That said, systems will be targeting our general area fast and furious and require us to remain on our toes. Given that a more prolonged period of cold is developing, we should be able to build a nice snowpack for outdoor winter enthusiasts over the next 7-14 days.

The setup is all thanks to a persistent negative to deeply negative AO and the associated high latitude blocking. The Pacific pattern is also changing to allow more meaningful cold (truly arctic air is getting involved in the pattern) into the East with staying power. We can thank the now negative EPO for that. That leads us to the PNA. A negative to even neutral PNA will continue to put resistance on the pattern and result in southern ridging at times. That’s especially true early on in this regime. That puts the Ohio Valley in the cross hairs of these systems. As the arctic air takes hold, I still believe eventually we’ll see a more suppressed storm track for a time but that likely doesn’t develop until late next week. Before that, we have multiple storms to track and a snowpack to build. 🙂

First up is an arctic wave that arrives Saturday evening. This is a system that should deposit 1” to 3” of snow, mainly from Indianapolis and points north (dusting up to 1” across the southern half of the state). This will be a fast moving system that will arrive around 5p across western parts of the state and will be out of here during the predawn hours Sunday.

Temperatures will crash Sunday morning into the single digits and highs will likely only climb into the middle teens. Good thing there’s a Super Bowl to focus on.

Additional upper level energy will result in light snow moving back in here Monday afternoon and night. With cold, arctic air in place, this system should be able to squeeze out an additional dusting to inch of snow (even as weak as it is).

That leads us to Tuesday night and Wednesday. A surface wave is expected to develop in the Ark-la-tex region and lift northeast. This will be a “juicier” event and result in widespread wintry precipitation across the state. Early thinking here is that across central and northern parts of the state, this will be mainly a snow event. Southern portions of the state may mix with sleet and/ or freezing rain. While we can’t throw out numbers this early, where it stays all snow, several inches seem likely.

If that’s not enough, more “fun and games” are dialed up with yet another system next Thursday and Friday. This, too, could be a meaningful winter event, locally, and will require close attention moving forward.

From a temperature perspective, it continues to look like a case of “delayed but not denied” on the topic of truly dangerous arctic air. As the pattern evolves and a snowpack is established, the concern here is that we’re looking at a period of severe cold (double digit below zero temperatures and wind chill values exceeding 20° below zero) by late next week/ next weekend.

More later today! Have a great Friday, friends!

Permanent link to this article: https://indywx.com/2021/02/05/buckle-in/

VIDEO: Pattern Drivers Starting To Align To Deliver More Sustained Cold As We Get Deeper Into Feb?

Updated 01.28.21 @ 6:30p

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VIDEO: Negative AO, Negative PNA Patterns Are Far From Boring…

Updated 01.26.21 @ 9:40p

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VIDEO: Detailed Breakdown Of Our Latest Thoughts Concerning Next Week…

Updated 01.21.21 @ 8:00a

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VIDEO: And The “Squeeze Play” Is On…

Updated 01.20.21 @ 7:45a

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Active Pattern Persists To Close January; Targeting Storm Dates…

Updated 01.19.21 @ 7:58a

Another upper level disturbance will push into Indiana this evening, providing a renewed shot of snow showers after dark, continuing into the overnight hours. Before we look at this and other storm dates of interest, I wanted to review the upcoming couple of weeks from a temperature and precipitation perspective.

While there weren’t a lot of changes overnight with respect to the ensemble guidance from Week 1 to Week 2, it’s fair to say the GEFS and EPS are trending in 2 separate directions- at least across the Ohio Valley into the Northeast Week 2. The theory here is that the differences come from the way the modeling handles the EPO and subsequent downstream ridge resistance. At any rate, confidence remains lower than normal in the 7-14 day period and it’ll likely take another 48-72 hours for things to become clearer during this time frame.

Week 1

GEFS Week 1 Upper air pattern
GEFS Week 1 Temperature Anomalies
GEFS Week 1 Precipitation Anomalies
EPS Week 1 Upper air pattern
EPS Week 1 Temperature Anomalies
EPS Week 1 Precipitation Anomalies

I would lean more on the European in the Week 1 timeframe (due to the precipitation pattern with forecasted trough/ ridge positions), though the solutions are similar, overall.

Week 2

GEFS Week 2 Upper air pattern
GEFS Week 2 Temperature Anomalies
GEFS Week 2 Precipitation Anomalies
EPS Week 2 Upper air pattern
EPS Week 2 Temperature Anomalies
EPS Week 2 Precipitation Anomalies

Despite the subtle differences, I would lean heavier towards the European solution again (retrograding eastern trough idea).

Storm dates of note include the following:

Jan. 24th-25th

Jan. 27th-28th

Jan. 31st-Feb. 1st

Expect continued wild run-to-run swings on the operational guidance as the data tries to understand the battle between the high latitude blocking (courtesy of the negative AO) and maturing negative PNA (will lead to southern ridging and more resistance as this gets established). These combined ingredients will lead to more of a question of wet vs. white, as opposed to a non-storm “event” that we’re dealing with Thursday-Friday. With the blocking in place, it’ll be tough to drive lows to the Great Lakes and we’ll need to watch for southward trends on guidance the closer we get to these potential storm dates of note above.

In the meantime, we have one more clipper system that will dive into the region this evening. This will offer up yet another round (the last in the series going back to last week) of snow showers after dark into early Wednesday (snow should be out of here by mid to late morning tomorrow). Snowfall accumulations across central Indiana can be expected to fall within the dusting to half inch range.

Permanent link to this article: https://indywx.com/2021/01/19/active-pattern-persists-to-close-january-targeting-storm-dates/

VIDEO: Tracking 3 Additional Upper Level Disturbances To Open The Week; Looking Ahead To Next Weekend…

Updated 01.17.21 @ 10:00a

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