Category Archives: Ensemble Discussion

Bet On The Cold…

During wholesale pattern transitions, operational data will struggle at times, including some wild run-to-run swings.  Earlier this week, the European wanted to put early next week in the lower 50s.  At the same time, the GFS suggested lower single digits.  Precisely, it was a difference of 46° between the two models for a high?!  🙂

We note the teleconnections (in particular, the EPO) are aligning in a manner conducive for widespread cold.

The GEFS might be a bit quick on dropping the arctic hammer, but the consistency of the model is impressive.  Meanwhile, the European (even it’s ensemble data) has been much less consistent and has really been struggling the past couple of winters, overall, as a whole.

While we can argue as to just how cold it’ll get through the early part of February, the overwhelming message is that a prolonged colder than normal pattern will develop during this time period.

Let’s also keep in mind that the initial cold onslaught is coming in the face of the MJO still rumbling through the warm phases.  We note the European is consistently having to correct towards a more “amped up” MJO- swinging into the cold phases as we approach mid-month.  And it’s mid-February that continues to have us concerned for the potential of truly nasty, severe cold.

As for snow, it’ll come in this pattern.  Again, don’t get caught up in the operational output, but understand that the pattern over the upcoming 7-10 days favors numerous fast-moving snow systems.  While most of these will be light, we’ll have to keep a close eye on things as the potential exists for one of these waves to spin up a moderate event.

As we look ahead to Week 2, the potential is there for a more widespread significant phased interior threat prior to the dumping of the bitterly cold air for mid-month.

As it is, both the GEFS and EPS “mean” paint a bullish signal for piling snow up over the next couple weeks…

No Comments AG Report, AO, Arctic Cold, Ensemble Discussion, EPO, Forecast Discussion, Forecast Models, Long Range Discussion, PNA, snow, Unseasonably Cool Weather

Arctic Hammer Drops Down Around Christmas…

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.

No Comments Arctic Cold, Christmas/ Thanksgiving, Ensemble Discussion, Forecast Discussion, Forecast Models, snow, Unseasonably Cool Weather

Tuesday Evening Rambles: Wintry Weather And More Christmas Week Chatter…

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.

9a forecast radar Wednesday

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…

No Comments Arctic Cold, Christmas/ Thanksgiving, Ensemble Discussion, Forecast Discussion, Forecast Models, snow, Unseasonably Cool Weather, Unseasonably Warm, Weather Rambles, Winter thoughts...

Intriguing Look As We Move Closer To Christmas…

Temperatures will attempt to approach seasonal norms Monday (average high this time of year is 40°) before arctic reinforcements blow into town Monday night and Tuesday.

This will keep highs in the middle 20s Tuesday with wind chill values in the single digits and teens most of the day.

Scattered snow showers and embedded lake-generated squalls will accompany this arctic surge Tuesday.  As the wind trajectory sets up shop Tuesday afternoon, lake effect snow bands will impact portions of northeast and east-central Indiana.

4a forecast radar Tuesday
10a forecast radar Tuesday
5p forecast radar Tuesday

Cold weather will continue to dominate through the work week and an additional upper level disturbance may try to ignite snow showers Thursday.

As we push into the 8-10 day time frame, a “relaxation” of the cold is anticipated, but, as we’ve been discussing, any sort of moderation will be brief in this weather pattern.  Cold looks to continue to dominate, overall.  With that said, there will be a window of opportunity early next week where temperatures will go above normal for a change and the European ensemble shows this brief moderation nicely.

This doesn’t last long as the pattern begins to reload as Christmas week approaches.  As the evolution to a fresh cold pattern takes place, there’s a window of opportunity present for a more significant wintry system to potentially impact the Ohio Valley into the Mid Atlantic region.  Notice the relatively “flat” ridge across the southern tier and associated tight thermal gradient.  This look suggests we need to be on guard for the chance of a storm system to ride the thermal gradient in a west-to-east fashion, and has wintry implications for our region.  Far too early for specifics; just know the possibility looms of a wintry event, locally, as Christmas week nears.

Speaking of Christmas, it sure appears as if cold will overwhelm the pattern for Christmas, itself, and the overall cold regime doesn’t show signs of letting up (with the exception of potentially a day or two) into the new year.

No Comments Arctic Cold, Christmas/ Thanksgiving, Ensemble Discussion, European Model, Forecast Discussion, Forecast Models, GFS, snow, Unseasonably Cool Weather