Category: AO

Wednesday Morning Video Update: Heavy Rain & Severe Threat Give Way To Much Colder Air And A Potential Late Weekend Winter Event…

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Whole Lot Of Weather Going On…

There’s sure no shortage of active weather, and unfortunately (or fortunately- depending on your perspective), there’s no letup in sight. As we look ahead, we see a fascinating battle of heavyweights set to duke it out for control of our mid and late February pattern. Before we get into some of the longer range model updates, let’s focus on the short and medium term challenges.

Heavy Rain

We continue to target (3) distinct windows where rainfall will be heaviest:

I. Late tonight-Wednesday morning

II. Wednesday night-Thursday morning

III. Thursday evening

In general, widespread 2″ to 2.5″ totals are expected in area rain gauges with heavier amounts across south-central Indiana (where flood risks are highest).

The other item to note? The potential of strong and gusty thunderstorms Thursday afternoon into the early evening. These would be located directly ahead of the cold front. While we’re not anticipating a widespread major event, temperatures and dew points will approach 60 deg. and the atmosphere will be favorable to support a few strong gusts that may mix down to the surface.

Sharply Colder

The cold front that will deliver the heavy rainfall for our midweek will sweep through central Indiana around 4p-5p. Behind the boundary, sharply colder air will blow in on strong and gusty northwest winds Thursday night. Daytime highs (actual highs will occur at midnight Friday) will only top out in the lower 20s with wind chill values in the 0s most of the day.

Winter Threat Late Weekend-Early Next Week?

The fresh batch of cold air in here to wrap up the work week will lay the ground work for potential wintry mischief late weekend into early next week. While the cold still isn’t set to truly establish itself (still think we’re a week-10 days away from that), just enough cold may be around to present the opportunity for an accumulating central and northern Ohio Valley winter threat in the Sunday-Tuesday period. Stay tuned as we fine tune things.

The hesitation that we still have from beginning to “ring the bells” a little louder in the aforementioned period is the position of the high in front of the storm and forecast strongly positive AO. Both of these argue against the idea of this being a widespread wintry event for the southern, and potentially as far north as central Ohio Valley. The early idea here as of now is that we’ll be looking at a wintry mix event to rain for central and southern areas with more of an opportunity for substantial snow across the northern portions of the Ohio Valley. Again, stay tuned as we continue to fine tune things.

Longer term, today’s MJO update continues to take things into Phase 8 and you don’t need us to cover the end result again (think cold) at this point. Should we get the other teleconnections to line-up (AO, PNA, NAO) then a 2-3 week period of significant winter weather would ensue during the 2/20-3/10 timeframe…

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+ AO Supports Current Warmth; Active Pattern Shows No Signs Of Letting Up Into Early March…

After the record-setting cold that gripped the Mid West and Ohio Valley for a few days, the recent “spring fling” has been welcomed with open arms by many! There are multiple reasons behind the warmth, especially with such a strong Arctic Oscillation (AO) in place.

We note the strongly positive AO (image 1) and the respective temperature anomalies that should result (image 2).

To no surprise, model data is bullish on the southeastern ridge holding firm this week.

The resistance put forth by the southeast ridge, combined with the renewed arctic air building across the Northern Rockies/ Northern Plains will continue to yield a very active storm track through the Ohio Valley. We expect precipitation to remain well above normal through month’s end, continuing into early March.

As we look ahead, we note modeling is trending the AO neutral and negative for mid and late month.

As this is taking place, the MJO is forecast to swing into Phase 8.

Phase 8 in mid to late February is a very cold phase.

Should the AO continue to trend negative, that will only raise confidence that cold will return.

Warmth (relative to normal) will continue to rule the day through midweek before we go into more of a transitional period this weekend into next week. Though certainly colder than this week, I’m not quite ready to buy into the idea that the southeast ridge will go quietly into the night. A couple of winter threats loom late weekend into next week, but confidence is low in the specifics. It’s when we get to the last (2) weeks of the month that we think cold will regain control, along with more widespread wintry threats of significance…

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Long Range: Cold Pattern Isn’t Going Anywhere Fast…

We’ll save our short-term discussions for the severe and high-impact arctic outbreak on deck and focus our attention in this post to the upcoming several weeks. In short, we don’t expect the cold pattern to break anytime soon. Could there be a day or two of “relaxation?” Yes, but from an overall perspective, confidence is higher than normal on the colder than average pattern continuing through the month of February.

Let’s dig in to the teleconnections:

EPO

AO

NAO

PNA


Given the teleconnections in agreement pointing towards a cold pattern, it shouldn’t come as a surprise that the majority of data is also on the cold train as we flip the page into February:

CFSv2 Weeklies

Weeks 1 & 2

Weeks 3 & 4

JMA Weekly

GEFS

While we aren’t licensed to show the European Weeklies, the new update runs with a cold pattern into early March. This falls in line with the overall consensus of longer range data, backed up by teleconnections.

Though not nearly at the amplitude of a few weeks ago, the MJO (Madden-Julian Oscillation) is forecast to move through Phases 5 and 6 in the coming weeks before going back into the “null” phase.


Phases 5 and 6 this time of year would suggest colder anomalies are more likely around our neck of the woods:

Given the above, we continue to think a colder than average “2nd half” of winter looms for the region. We lean heavily on the NAO, EPO, and AO state(s) this time of year and all would point towards a cold time of things moving forward, overall. The latest European Weeklies are interesting from a couple of fronts- initially very cold and then progressively stormy. The idea here is that we remain quite wintry through February and into early March before this pattern breaks. While we may not see a “repeat” visit of the Vortex, it wouldn’t surprise us to see another major arctic outbreak again this winter (after next week), but that likely comes later, and towards the end of the game before we snap into spring.

Buckle up; we think we have a long way to go this winter…

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VIDEO: Long Range Update; And Looking At This Weekend’s Snow Storm…

Tonight’s video update focuses on the long range and reviews some of the fresh short-term data churning on this weekend’s snow storm.

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