Category: PNA

Jul 27

A Different Kind Of “Dog Days” This Year…

Late July and August have been known to produce some serious heat around these parts from time to time. However, it continues to look like this will not be the case this year.

We’ve already discussed the impacts of the negative EPO. (By the way, modeling continues to take the EPO even more strongly negative with every passing update). This supports the cooler idea we have for early August.

Now we see the PNA forecast to trend more positive through the better part of early August. This, too, supports the cooler pattern that will be with us through the period.

It should come as no surprise to see the models trend stronger with the eastern trough in the Weeks 2-3 time period. This period will likely feature a couple of strong frontal passages that serve as a reminder that the fall season is just around the corner.

Note the latest GEFS deepen the trough from the Day 5-10 period to Days 10-15.

Not only will this serve to provide a rather lengthy period of cooler than normal temperatures through the 1st half of August, but should also help inject wetter conditions to boot (in large part due to the frequent nature of frontal passages).

At a time of year that can feature brutal periods of heat and/ or dry conditions, it sure continues to be the exact opposite this year!

Enjoy your Saturday, friends!

Permanent link to this article: https://indywx.com/2019/07/27/a-different-kind-of-dog-days-this-year/

May 06

More Evidence Behind Mid-May Shift To Cooler And Drier…

Though May has opened warmer than average (to the tune of 1 degree F above normal, month-to-date), there’s growing evidence behind a shift towards not only a cooler pattern for mid-month, but drier, as well.

MJO:

The Madden Julian Oscillation is forecast to move through Phase 7 (a cooler phase in May across the eastern half of the country).

PNA:

The Pacific North America pattern is forecast to remain positive into mid-May. This favors a cooler than normal south-central into the eastern portion of the country, as well.

To no surprise, we see modeling now in excellent agreement of the cooler mid-month shift that awaits on deck. Recall that this wasn’t the case last week when the GFS and EPS were in vast disagreement.

The cooler shift also will provide relief from the seemingly unending wet regime we’ve been in as of late.

Hang in there; after a warm, wet open to the month, the pattern will begin to shift around in significant fashion as we move into the weekend and beyond…

Permanent link to this article: https://indywx.com/2019/05/06/more-evidence-behind-mid-may-shift-to-cooler-and-drier/

Mar 21

More On The Late March-Early April Pattern And Reviewing The NEW JMA Weeklies…

As we look ahead, a persistent western Canada/ Alaska ridge continues to show up on the medium to long range data. The downstream implications are for cooler than normal temperatures, overall, across the eastern and central portions of the country into early April.

Upper air pattern- Days 4-9
Surface temperature anomalies- Days 4-9
Upper air pattern- Days 9-14
Surface temperature anomalies- Days 9-14

Given the time of the year (and pattern), cool won’t rule the entire period. It’s just that the cold will “out do” the transient warmth in between storm systems over the next couple of weeks.

When we look at the teleconnections (combo of negative EPO and neutral to slightly positive PNA is ruling the day for now), they support the lingering chill into early-April.

However, as we turn the page from early-April to mid-April, the idea here is that an eastern ridge will begin to expand west with more “umph” and eventually lead to warmth overwhelming the pattern. We aren’t budging from the original idea of a warmer than normal April by month’s end. It sure appears as if the NEW JMA Weeklies are catching onto this idea.

Weeks 3-4 (mid April) forecast upper air pattern.

From a precipitation perspective, the majority of medium and long range model data does show a return of wetter times (relative to normal) as we move into April, including an active storm track. The beginning of this overall shift in the pattern back towards wetter than normal conditions will begin early next week.

We’ll recap our latest short-term thinking, including an update on the NEW European Weeklies that will arrive this evening later tonight in a video update.

In the meantime, make it a fantastic Thursday- and happy tip off to March Madness!

Permanent link to this article: https://indywx.com/2019/03/21/more-on-the-late-march-early-april-pattern-and-reviewing-the-new-jma-weeklies/

Mar 19

Disruption In The Force…

There are growing indications the once thought warm flip in the pattern will be delayed. While “seasonality” is helping us certainly improve in the temperature department from the frigid open to March, data is trending (and some dramatically so) colder for late March and early April.

Part of this can be attributed to the persistent AK ridge and positive PNA/ negative EPO pattern in place. Without question, medium and long range modeling as early as less than a week ago missed this. Note the above image and tendency for prolonged ridging across AK into early April. This will favor cooler anomalies downstream, including here across central Indiana. That’s not to say there won’t be multiple warm and pleasant days thrown in the mix (it’s late March, after all), but instead to say that the pattern overall looks much cooler when compared to what the majority of data was painting only a handful of days ago.

Embedded within this pattern will come a return of active times, including multiple storm systems of note over the upcoming 10-14 days. The flavor of said systems will change from originally thought as hefty rain and potential severe events to rain and perhaps some wintry precipitation. With that said, specifics are impossibly to come by in this “chaotic” pattern and we suggest staying tuned as we get closer to the arrival of the first system early next week.

Like your weather pattern “interesting?” You’re in luck over the upcoming couple of weeks…

Permanent link to this article: https://indywx.com/2019/03/19/disruption-in-the-force/

Mar 11

Long Range Update And Summer Preview…

One more unseasonably chilly spell awaits late-March (behind our mid-March spring “tease”), but we continue to believe an unseasonably warm stretch of weather gets going by the last few days of the month- continuing into April. Furthermore, meteorological spring overall continues to look warm, relative to average, for central Indiana. In the event you missed our Spring Outlook earlier, it can be found here.

However, what follows the late-March set-back is a more significant and sustained push of unseasonably warm conditions.

Note the positive PNA that will help drive the chilly pattern next week returns to neutral as we put a wrap on the month:

To no surprise, modeling is painting a vastly different look as we close March and open April.

We turn cooler next week with the positive PNA in control, but this won’t last…

Note the significant change aloft (and at the surface) as we close the month and get set to head into April…

Longer term, modeling continues to give us an actual spring this year. We continue to expect average to slightly above average temperatures in April, complete with slightly above normal precipitation (with a “ramp up” in severe chances, locally).

Modeling is following suit with that idea:

It should also be noted that while not shown, the new European Weeklies in this evening also support the warmer than normal April idea.

As we look forward, we continue to research and build our summer outlook. Early indications would suggest that we transition out of an overall warmer than average spring towards a seasonal, to slightly below average, time of things this summer, complete with above normal precipitation. We, obviously, still have some time to go before the final product is ready to be published, but stay tuned. We are planning to launch our official summer outlook in early May.

Permanent link to this article: https://indywx.com/2019/03/11/long-range-update-and-summer-preview/

Mar 10

VIDEO: Weekly Outlook; More Around The Late March Pattern…

Looking at the week ahead and the pattern as we move through the latter portion of March…

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Permanent link to this article: https://indywx.com/2019/03/10/video-weekly-outlook-more-around-the-late-march-pattern/

Mar 07

Long Range Video Update: Changeable Pattern For The 2nd Half Of March Into April…

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Permanent link to this article: https://indywx.com/2019/03/07/long-range-video-update-changeable-pattern-for-the-2nd-half-of-march-into-april/

Mar 07

All-Access Video: Talk About a Busy Pattern…

Accumulating snow arrives tonight and we look ahead to an active weather pattern…

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Mar 06

Running the Gamut; Looking Ahead to April…

We’ll apologize in advance for the long-winded post tonight, but there’s a lot to cover. Not only do we have the accumulating snow on deck, a couple of strong storm systems this weekend into the middle of next week, but the long range pattern is set to turn cold (again) after a mid-month respite. We also want to look ahead to our early thoughts towards April…

Let’s take things one at a time:

Thursday-Friday Snow

While we don’t have major changes to our ongoing snowfall forecast, we have “sagged” the swath of 1″ to 3″ snow south just a hair given the latest computer model guidance. Steadiest snow should fall Thursday night into the predawn hours Friday. We’d anticipate a slick Friday morning commute through the heart of central Indiana.

Snow should exit off to the southeast around, or just before, lunchtime Friday. As always, your ground-truth reports are welcome (feel free to send to us on Twitter or via e-mail).

Warmer Side Of Things

The ‘mean’ trough position will shift to the west (temporarily) and lead to an overall milder time of things for the mid-month stretch. Unfortunately, the milder air will come with a wetter pattern.

This milder, wetter pattern will be highlighted by (2) storms:

I. Saturday, 3/10

II. Tuesday-Wednesday, 3/12-3/13

Both storm systems will be capable of producing locally heavy downpours and embedded thunder. Greatest chances of severe will remain south of central IN with this weekend’s storm, but may be further north next week. We’ll keep a close eye on things and issue Client Briefs if need be as we get closer.

A combination of the GFS and European computer models print-out rainfall totals between 1″ and 2″ over the upcoming 10-days and this seems reasonable given the fact both storm systems will be able to tap into Gulf of Mexico moisture.

From a temperature perspective, the brutal cold will come to an end behind our late week snowmaker. While “transient” chill will follow both of the upcoming storm systems, we’re heading into a much milder pattern, overall, through the mid-March stretch. Mildest air will come directly in front of the storm systems, highlighted by a couple of 60 deg. + days the middle of next week.

Positive PNA takes over

Unfortunately (for lovers of spring), the mid-month warm-up will be only a “tease” as we’re set to trend cooler, relative to normal, for the last 10 days of the month. The reason? A developing positive PNA.

To no surprise, we see the cooler pattern returning on the computer models:

Not only will we turn colder to close the month, but Thursday likely won’t be our last accumulating snow of the season…

Looking Towards April

Despite the late-March “set back” to a chilly time of things, we continue to think a more sustained “stick and hold” spring pattern looms around the corner. In fact, we agree with the latest CFSv2 delivering a warmer than normal pattern for April, as a whole, to the eastern portion of the country.

Note that as we go, the model is getting warmer for April with each passing day. As things stand now, we think the trough will pull back to the west with a more sustained ridge in place across the eastern portion of the country in April. With this, a wetter than average regime likely awaits, including an uptick in severe chances further north into the region.

Permanent link to this article: https://indywx.com/2019/03/06/running-the-gamut-looking-ahead-to-april/

Mar 06

“Hectic” March Pattern Rumbles Along…

After tomorrow’s accumulating snow event, we’re tracking 2 storm systems and a temporary warm-up over the weekend into next week. Don’t get used to the warmer air, as a positive…

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Permanent link to this article: https://indywx.com/2019/03/06/hectic-march-pattern-rumbles-along/

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