The storm system that will impact the region late this week will really be a precursor of what lies ahead over the upcoming 10-14 days.
Here’s how we envision the ‘mean’ pattern shaping up through the January 20th time period:
This pattern is driven by Phase 5 of the Madden Julian Oscillation (MJO) and, secondarily, by a positive EPO.
Upper air patterns in January typically look like this during MJO Phase 5:
The analog composite above isn’t as strong compared to reality with the northern Plains/ Rockies cold and that’s where things could potentially turn a bit more interesting, locally, once out of Phase 5 (more on this a bit later in the week). As it is, this cold will try to press and as this takes place, resistance from the East Coast ridge will put up a fight. The battle ground will set-up over our neck of the woods and the end result will be an active/ stormy pattern that features “transitional” cold shots. This time of year, even warmest of patterns can present wintry challenges, however. Case in point is this weekend. Personally, I think what will actually take place with respect to the strength and track of the low pressure system will end up being a blend of the intense European and more progressive GFS. It’s going to be mighty tough to drive such an intense low so far northwest, per the Euro- especially considering the placement/ strength of the high to the north.
With that said, this continues to place northern parts of the state under the threat of a wintry mix of snow and freezing rain/ sleet, while central and southern areas deal with flooding rain. If traveling the state Saturday, expect a significant temperature gradient that will result in a difference of as much as 20° within 10 miles in some cases, especially across north-central parts of the state. I think there’s still the chance rain could end as wet snow across central Indiana Saturday PM, but the better chances of accumulating wintry precipitation will likely be to our north.
Locally, the bigger concern at this point has to do with the potential of 2.5″ to 3.5″ of rain with locally heavier amounts. The bulk of this likely falls late Friday night into Saturday morning. Localized flooding is possible and we’ll likely have to begin issuing storm briefs this time tomorrow.
Next up will come storm threats in the 1/14 and 1/16-1/17 time frame…
Stay tuned, friends.
The early spring “fling” has lulled many into believing winter’s finished. While the worst of the winter is certainly behind us, we continue to think a dose of “reality” awaits as we progress through the better part of the first half of March. To be more specific, we feel the period March 6th through the 20th will offer up below average temperatures and an active pattern- capable of producing wintry threats.
Sure enough, modeling is going to the pattern that will produce below normal temperatures (doesn’t appear to be anything particularly frigid, but colder than average, nonetheless) through mid-month.
With blocking in place, an undercutting jet will serve to deliver an active storm track.
Keeping in mind March winter events need multiple items to come together to create impactful situations, it’s also important not to simply “buy in” to the idea that just because it’s been warm lately that winter is finished. March can be a wild month, as long-time Hoosiers are aware. The pattern we’re heading into over the next 10-14 days is one that’s been void most of the winter (high latitude blocking in place) and can serve as the player needed to flip a “nuisance” variety late-winter event to one that’s much more significant. We’ll need to remain on guard for the potential of one or two “more significant” wintry events as we move through the first couple weeks of the month.
The end result is one that should promote colder than average times over the next couple weeks, overall, along with an active storm track. With blocking in place, the potential of one or two more significant late-winter events are on the table, and we’ll have to fine tune specifics as the individual storms come. While confidence is high that someone within the Ohio Valley region is likely to still deal with a big-hitter event, there’s no way to get specific until the individual players are on the field. Thereafter, the pattern should begin to transition to one more conducive for “stick and hold” spring conditions during the latter portion of the month.
Speaking of warmth, 2016 has been a very warm year.
(The cold of 2014 seems so long ago…)
Back to present. We’ve targeted the middle part of November to finally beginning “bucking” the recent warm trend. This won’t happen overnight and will be a battle of back and forth, initially. Thus, the “step-down” label. To be clear, November, as a whole, will finish much warmer than average. It’s virtually impossible to counter the incredibly warm start. That said, we do anticipate “jabs” of colder air working in here over the next couple weeks. For instance, this weekend will feature lows in the 20s for most and highs not making it out of the 40s Saturday afternoon. (The average low and high at IND Saturday are 37 and 54).
When we look at the AAM forecast (above), we note the westerlies may begin to slow (indicative of the negative values) in the 8-10 day period. This is crucial and, simply put, has to happen for the pattern to begin shifting into more of a position to allow sustained cold to enter the equation. We want to reiterate that this, in and of itself, doesn’t create the cold, but instead allows the pattern to begin shifting away from the Nino-like (warm) regime into more of a La Nina pattern, as a whole. – Hey, you have to start somewhere.
Additionally, the EPO is forecast negative off the GEFS and EPS. (Images courtesy of Weatherbell.com).
Again, this is a cold signal. (Image courtesy of Madusweather.com).
The ensemble data is also beginning to key-in on higher heights (blocking) developing over the top. Notice the significant changes in the overall look to the pattern between now and days 11-16. (Images courtesy of Weatherbell.com).
In summary, and in the face of *most* seasonal data that is screaming warm, warm, warm, we still don’t have any significant changes to our overall thinking of “step-down” mid-November giving way to more sustained wintry-like conditions in the overall sense from the Thanksgiving-Christmas period. Time will tell and only the Good Lord knows what the future holds, but we’ve done far too much work and research to throw the “game plan” in the trash before the game even begins…
