Jan 12
A look at the latest European forecast model shows the way we think things play out this week nicely. I hope you’ve enjoyed the relatively milder pattern for a few…
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Permanent link to this article: https://indywx.com/series-of-cold-jabs-this-week/
Dec 23
We continue to be very impressed with the cold pattern that’s looming. Even before the warm up and thaw last week, we made mention that the seeds were being planted for a very cold close to December and open to 2014. Latest data continues to back this idea up. Additionally, in the longer term, there are some goings on that would suggest we better hunker down for a colder than average January. While December will finished colder than average, a colder than average January can really hurt the pocket book as “average” temperatures are obviously even colder than December.
Today’s 12z ensembles are locking in on the pattern than can deliver one shot after the other of arctic air in the 8-10 day range.
As for the snow, we still think we need to watch the models around the New Year for the threat of some southern stream energy interacting with the available cold air. That said, even without the southern stream, one must remain abreast of the challenge that a northwest flow pattern can produce.
Forecast models have a difficult time handling clipper systems in these type of patterns until within 24-48 hours within an event. Many times what appears to be a rather “harmless” clipper 4-7 days out can suddenly turn much more robust once the model catches onto the track and ability to literally squeeze out any and all available moisture from a cold air mass. Furthermore, the “normal” 10:1 snow ratio, many like to use, doesn’t apply in the least to these type systems. In cold environments you can easily get what’s called the “fluff effect” and snow ratios are more in the 20-30:1 range. Needless to say, it’s a challenging pattern that will keep us on our toes over the coming couple of weeks.
To summarize, we’re extremely confident on a colder than average close to December and open to January. We’ll have to monitor fast moving clipper systems that modeling will struggle with until right up to the event. Finally, we’ll keep a close eye on the potential interaction of the southern stream and cold air around the New Year time period for the possibility of a storm of “more significance.” Stay tuned!
Permanent link to this article: https://indywx.com/impressive-cold-pattern-looming-beware-of-the-northwest-flow/
Dec 18
Mother Nature seems determined to put us weather forecasters to hard work as we get set to head into the Christmas season and welcome in 2014. We’re tracking a major flood situation that will unfold across central Indiana over the upcoming weekend, followed by a reload of the cold and potentially a storm with a more wintry component as we get closer to the New Year.
First things first and that’s the significant flood threat in the short-term period. Without trying to go into scare tactic mode, current model data would result in a downright dangerous flooding event for many low lying and flood prone areas this weekend. Rainfall numbers are extremely impressive with this event and with a deep tropical connection, widespread 3-4″ totals are certainly likely, including some localized higher amounts. Note the latest European chart, courtesy of the model suite off Weatherbell Analytics. Needless to say, the Gulf of Mexico is officially “open for business” and will help contribute to excessive rainfall totals and, as stated above, potentially a dangerous flooding event this weekend across central Indiana.
Latest numbers averaged off a variety of computer models would place just under 4″ of rainfall down by noon Sunday, most of which falls between Friday and Sunday morning. We note (2) waves of enhanced rainfall intensity set to impact the region. As of now we’re targeting Saturday afternoon and again late Saturday night/ Sunday morning for extremely heavy rain, shown below.
We still have time to watch the data and monitor the track of the storm. It’s possible the “heaviest of the heavy” axis of rain shifts somewhat in the days ahead, but it’s also important to note that even a light to moderate rain event combined with a frozen ground and a solid snow pack still in place will lead to flooding problems here across central Indiana. The question of whether or not we’ll deal with flooding here this weekend shouldn’t be asked, but instead the question that remains is just how severe will the flooding be? Stay tuned and if you live or work in a flood prone area, we would recommend preparing now for flooding.
Now, as we look ahead and focus on the Christmas to New Years period our thoughts will shift from a flood threat in the near term to one that’s more wintry. We’ll turn dramatically colder Sunday afternoon behind the big rain storm and that will set the stage for a colder-than-average run up to Christmas. In fact, latest raw numbers off some forecast model guidance has some frigid readings ahead next week (upper single digits not ruled out for lows).
The upcoming 10 days off the European forecast model charts show an interesting scenario with the coming thaw, but the key word is brief. Note days 6-10 are back into a colder-than-normal regime.
Additionally, we think we’ll have to deal with another storm prior to the New Year period and with the colder air back in place, there’s the threat we could have to contend with a wintry side to the next storm. The details with storm number two will have to wait until we finish dealing with the first storm and associated serious flood threat it’s presenting.
Permanent link to this article: https://indywx.com/a-lot-of-weather-to-talk-about/
Dec 11
Latest data in house still suggests a plowable snow is ahead for most of central Indiana this weekend. We think wintry precipitation expands northeast to encompass all of the region between 7pm-9pm Friday evening (southwest to northeast). This wintry precipitation still appears to take the form of all snow for IND and points north, but we caution that south-central Indiana communities will have to deal with a mixed bag of precipitation, including sleet and perhaps some freezing rain along with the snow. The primary snow zone will have no trouble seeing snow amounts of 4-5 inches, but for south-central Indiana neighborhoods, snowfall accumulations appear to be closer to 2 inches, with additional accumulations of sleet also possible. Needless to say, we feel pretty good about our initial snowfall forecast posted last night in our 7-Day forecast video (always available to the right of these posts in the video player). The limiting factor, in our opinion, of even higher snowfall totals will be due to the speed of the system. We think this is primarily a quick 6-8 hour “thump and go” type snow storm followed by some lingering light snow/ snow showers and gusty winds Saturday PM. The sunshine returns for Sunday along with another surge of bitterly cold air with highs in the 20s.
Friday night-Saturday Snow Storm Highlights:
Our attention then turns to what may lie ahead Christmas week. After the chance of some brief “relaxation” from the current bitterly cold pattern, we look to reload the cold with authority around Christmas week. In fact, if latest data comes to fruition, the current cold would pale in comparison to what lies ahead. Additionally, a rather significant storm system could precede the arctic blast. It’s far too early to talk specifics on precipitation type or amounts, but don’t be surprised if a storm of “significance” is on the maps as we approach Christmas week…
The latest ensemble plot from the GFS and European (below) agree on first class cross-polar flow setting up shop, which will help refrigerate the Lower 48 with some seriously bitter air just in time for Christmas. Stay tuned…
Permanent link to this article: https://indywx.com/snow-talk-and-a-look-ahead-towards-christmas-week/
Nov 24
As we approach the all-important holiday travel season, I thought it would be nice to review what some of the data suggests in the long range sense. While nothing is “set in stone” talking about weather 2-3 weeks out, we feel pretty confident in the overall idea of a colder than normal pattern and one that’s also potentially wintry- from a precipitation perspective. The specifics with each storm will have to be handled as they come.
Let’s look at some of the data. BTW, I want to give full credit to the awesome model suite that can be found at Weatherbell Analytics for some of these images. Be sure to check them out at weather bell.com.
First, we’ll take a look at the Canadian ensembles, centered on the 8-16 day period. Note the tongue of cold coming out of western Canada, extending southeast and encompassing the Ohio Valley region. Folks, this is significant cold forecast off the Canadian ensembles as temperatures are suggested to average 5-7 degrees (C) below normal.
The latest GFS ensembles also suggest widespread colder than normal temperatures over the upcoming couple weeks. Similar to the Canadian (above), the GFS suggests temperatures average 5-7 degrees celsius below normal.
Latest European ensemble data suggests a cold look as well, but one that also may feature a day or two above normal (over the next couple weeks). The latest ensemble control run highlights the threat of some bitterly cold arctic air plunging south towards the second week of December (posted below). We’ll continue to monitor this in the days to come.
Here’s a look at the latest CFSv2. While it’s in stark contrast to only a couple of weeks ago (in its December forecast), the model is now onboard with most other data in forecasting a colder than normal December for our region.
It has to be pointed out that all of the cold data is forecast during a time where the three “major” teleconnections really aren’t in the most ideal spots for eastern cold. Typically, cold lovers across the eastern United States want a negative AO and NAO with a positive PNA. The NAO and AO are forecast to be very “sporadic” over the course of the upcoming 7-10 days while the PNA is forecast to go back negative. That said, the NAO has the biggest influence on our weather from January through March (we’ve covered this in posts in the archives). The expansive early season snow and ice pack through western Canada is having it’s say with a couple of early season “brutal” cold shots here (it’s very rare to get this kind of cold so early in the season). We’ll continue to monitor these teleconnections moving forward for any sort of a more defined signal that may begin to come to fruition.
Speaking of snow and ice cover; look at how much more territory across the Lower 48 is covered with snow and ice compared to this date (November 24th) last year. Impressive, huh?
November 24, 2012 (11.8% covered in snow)
November 24, 2013 (37.8% covered in snow)
As we look closer at the near term, there’s a chance of some light snow moving in Monday evening (not a huge deal, but some light accumulations of a dusting to half an inch are possible). Scattered snow showers will also blow into central Indiana Wednesday as a reinforcing shot of fresh arctic air blows in prior to Thanksgiving.
In the mid range, both the GFS and European ensembles (below) suggest an “intriguing” look for the first 10 days of December for the potential of a more widespread winter weather maker. It’s far too early for details, but with arctic air being supplied into a pattern that looks to have a southern branch beginning to flex it’s muscle, we’ll have to remain on our toes as we go into December… Here’s wishing you a very happy and healthy Thanksgiving, complete with safe travels!
Permanent link to this article: https://indywx.com/data-suggests-cold-pattern-keeps-on-keepin-on/