- Category Archives Christmas/ Thanksgiving
- Unseasonably mild for now
- Dry midweek
- Turning colder and wintry as Christmas approaches
Bottle It Up…By this time next week, most will want to go back in time to the unseasonably pleasant December weather we’re currently experiencing. If you’re one of these individuals, it’s too bad you just can’t bottle it up for the frigid times that loom.
The short-term period will continue to be dominated by relatively quiet conditions given the time of year. A storm system will pass to our south Wednesday and provide the Tennessee Valley a good soaking. We’ll turn cooler for midweek, but remain well above seasonal averages.
A cold front will move towards the region as we wrap up the work week. This will deliver showers Friday into Saturday before colder air results in a potential transition to wet snow Saturday. Thereafter, details remain sketchy (at best), but overall confidence is increasing in at least some snow falling during the Christmas Eve – Christmas morning period.
Models are struggling with a second piece of energy that will blow through prior to the big cold blast next week. Typical model biases are showing themselves this morning (more progressive GFS versus the more amplified European and Canadian). The best idea at this point is to go with a blend and trend towards a period of snow developing during the afternoon and evening on Christmas Eve, but please understand we’ll have to fine tune things over the next few days. The other item to consider is that it won’t take much upper energy at all to ring out any available moisture as the arctic intrusion arrives.
Regardless of whether we enjoy Christmas snow or not, the period next week into early parts of 2018 looks particularly cold (at times bitterly so) with additional winter weather opportunities. Snow removal companies might want to begin stocking up on the coffee!
Upcoming 7-Day Precipitation Forecast:
- Snowfall: 1″
- Rainfall: 0.50″ – 0.75″
While the evolution of how things transpire from a snow perspective are “murky,” at best, confidence continues to run very high on the prospects of a nasty period of bitter air arriving around Christmas.
Before we dig into the cold details, the pattern is one that still screams “trouble” from a wintry perspective in the December 23rd-Christmas Eve period. We posted over the weekend of the PNA-EPO going to battle Christmas weekend, and before the cold overwhelms, a consensus of the data continues to paint an interesting scenario as resistance will be present initially from the southeastern ridge. Modeling will continue to struggle with this evolution over the next few days, but we’re hopeful we’ll begin to gain more clarity by late in the work week. Needless to say, a stripe of impactful wintry precipitation should fall in a southwest-northeast fashion given the pattern, but whether that’s to our northwest, over our region, or off to our southeast is simply impossible to call from this distance. A glance at the individual ensemble members (GEFS shown below) shows this nicely, as well. The European ensemble members also paint a similar picture.
Hang in there as we continue to sort through the data over the next few days. Once confidence increases (for or against an event), you’ll be the first to know! 🙂
Now to the ugly stuff: Bitterly cold air of true arctic origin will be dislodged southeast late week and encompass more of the country by Christmas weekend. Eventually, this arctic air will make it across the Appalachians and reach the East Coast just after Christmas.
Recent operational data (GFS and Canadian included) has suggested a sprawling high in the range of 1050mb+ descending into the eastern slopes of the northern Rockies. Such a regime would be plenty capable of spreading sub-zero temperatures east into the Ohio Valley (with or without snow on the ground). Add in a biting north wind and wind chill values would drop to levels of dangerous and deadly levels if any length of time was spent outdoors. Some of the latest data paints a picture similar to shades of the famous ’13-14 winter (20° to 30° below zero chill factor). If you have travel plans over the Christmas holiday, please plan in advance to have a winter survival kit packed and loaded. It absolutely never hurts to be prepared.
- Light showers later today
- Mostly quiet weather week awaits
- Much colder as Christmas nears
Sunday Showers…A weak weather system is approaching the state as we type this forecast update. That system will deliver light showers through the afternoon hours, but this won’t be a major weather event by any stretch of the imagination- more of a nuisance than anything.
Our next “event” will come Tuesday night in the form of a dry frontal passage. This will trend us cooler Wednesday, but still above seasonal norms. Quiet times will persist with sunshine through midweek, allowing last minute shoppers (no finger pointing here :-)) to at least not have any weather worries as they finish checking off the list!
A more significant cold front will approach as we close the work week. This will provide showers and gusty winds, followed by a colder feel late in the day.
Looking ahead towards Christmas Eve and Christmas Day, confidence continues to remain high on a much colder pattern taking hold. However, it’s purely speculative at this point whether we’ll be enjoying “white” for the big day. Stay tuned.
Upcoming 7-Day Precipitation Forecast:
- Snowfall: 0.00″
- Rainfall: 0.20″ – 0.40″
One of the many ingredients we like to throw into the mixing bowl when developing our medium range forecast is the teleconnection breakdown. Many times, the various teleconnections play into themselves and agree, but, at times, conflicting signals lead to a fight. At any given time, one or the other “big boy” teleconnections can take control of the pattern and simply overwhelm. As things stand now, it appears as if the two teleconnections trying to control are the EPO (Eastern Pacific Oscillation) and PNA (Pacific North America pattern), highlighted below.
As we’d expect, as these two fight it out, a battle will ensue across the central and eventually eastern portion of the country. The negative EPO is a widespread cold pattern, while a negative PNA favors south-central and southeastern ridging (a warmer pattern).
When we look at the latest ensemble data, we see this battle playing out within the modeling.
Eventually, we expect the deeply negative EPO to take control and overwhelm the pattern with cold. However, as this transition of power takes place, the negative PNA won’t go down without a fight and will likely play a role in the weather leading up to Christmas.
The negative PNA suggests we need to remain on guard for the potential of an interior snow/ ice event around Christmas. As we’ve been mentioning, from this distance there’s no way to say whether this is an impactful wintry event for our region, or just to our north or south. We should be able to become more detailed within the next few days…
- “Can’t beat it” weather for mid-December
- Raw second half of the weekend
- Changes loom
Great Open To The Weekend…High pressure and a relatively mild southwest flow will help boost temperatures to near 50° Saturday afternoon, complete with plentiful sunshine. We will note an increasingly gusty southwest breeze late in the day.
The second half of the weekend will feature an increasingly wet period, along with a “raw” feel. Rainfall amounts won’t be particularly impressive, but rain gear will be required on the way out to church Sunday morning.
High pressure will quickly build back in thereafter and remain in control of our work week weather. A nice stretch of pleasant conditions (by mid-December standards) will prevail, including plentiful sunshine. Enjoy it as big changes loom.
The all-important Christmas-New Years period is growing ever closer and data continues to suggest we should gear up for busy times in the forecast office. An active pattern looms, including one that will trend progressively colder.
Upcoming 7-Day Precipitation Forecast:
- Snowfall: 0.00″
- Rainfall: 0.10″ – 0.25″
I.) The pattern we’re currently dealing with is one that presents multiple challenges in the near term. East-central and northeastern portions of the state have gotten in on the snow act today, but, so far, most of central Indiana has missed out on the snowy goods. With such a fast-paced northwest flow, we have to remain on guard for potential “surprises” in this pattern. Perhaps the HRRR is beginning to pick up on this. Latest runs want to deliver a “pop” of snow Wednesday morning, associated with “warm” air advection (WAA). We’ll monitor tonight.
II. The northwest flow will continue to provide disturbances plenty capable of producing periods of snow again Wednesday evening through the end of the week. Are these monster storms? Hardly, but they can “suddenly” become sufficient enough to create travel problems given the pattern. For those who live across the northern half of the state, plan to keep close tabs to local forecasts if you have travel plans through the end of the week.
III. A period of brief moderation will come in this pattern early Christmas week, but all eyes continue to focus on the period between December 22nd through December 26th for the potential of impactful weather across our region. For model “worshipers” out there, we suggest paying more attention to overall trends, and a blend of ensemble data, as opposed to specifics associated with operational runs. It’s a “jailbreak” pattern of sorts as true arctic air will be pouring down the Plains while the southeastern ridge tries to fight for a time. The resistance from the southeastern ridge and associated tight thermal gradient should promote a very stormy regime for the interior (Ohio Valley into the interior northeast) as we head into the true holiday/ Christmas stretch. As of now, we favor the idea of multiple waves along the pressing arctic boundary, as opposed to one big storm. Looking back through the records shows some of the heaviest snows at IND have come from similar set-ups. Understanding each set-up is unique, the overall pattern does have to raise an eye brow for potential of wintry weather in, or around, our region as Christmas approaches…