Folks are growing tired of the cold and snow, and for good reason; it’s mid-April for goodness sakes. As of today, we’re currently ranked as the 5th snowiest spring (March-May) in recorded history, with Indianapolis recording 14.2″ thus far. By the way, we’re only .3″ from moving into the 4th place spot.
With that said, it’s not just April that’s been unusually cold and snowy, but the entire year thus far. As of April 15th, year-to-date CONUS temperatures are running more than 1° below average:
More specific to Indianapolis, here’s the monthly temperature breakdown so far for 2018:
- April: 5.7° below normal (MTD)
- March: 3.3° below normal
- February: 5.6° above normal
- January: 3.0° below normal
As we look ahead, there are a couple of key items that we’re monitoring closely to get a better idea as to where this pattern is heading as we rumble into the merry month of May:
NAO- does it show signs of finally flipping to a positive state with any sort of duration?
MJO- does it go into the “wheelhouse” or continue to rumble into the milder phases (5 and 6 this time of year)?
The North Atlantic Oscillation (NAO) is a bit troubling as it shows signs of heading towards a negative phase once again as we open the month of May. This would promote the threat of colder than normal temperatures continuing in early May. With that said, May is the first month of the next several (until winter returns) where the overall influence of the NAO state begins to lessen it’s grip. Unlike from the mid and late winter months into the early spring (Jan through April), mid and late spring, through the fall, isn’t controlled by the NAO. With May being a “transition” month, we’ll favor a colder than average pattern continuing during the early portion of May as the NAO looks to trend negative. As we move towards mid and late month, we won’t rely on the NAO like we have been lately as the said influence “wanes.”
The Madden Julian Oscillation (MJO) is forecast by most data to head towards the “null” phase. The consensus of modeling takes it into the wheelhouse after traversing Phase 3 (present) which is a cold phase. The end result? Unfortunately, we can’t rely on the MJO with any sort of confidence from this distance for the month of May.
Looking at the data itself, the CFSv2 and European Weeklies (just to name a couple) show conflicting ideas. The CFSv2 (courtesy of weatherbell.com) is in the warmer than normal camp for May while the NEW European Weeklies (courtesy of weathermodels.com) suggest the chill lingers throughout the month.
While we have conflicting temperature ideas, both suggest a drier than average month emerging:
At the end of the day, our call on May’s forecast from mid-April would be for an early cooler than average start before flipping towards more of a seasonable to slightly warmer than normal regime. Our idea all along this spring has been that when this pattern flips, the potential is present to jump right to a summery feel. In the face of the new European Weeklies, we still feel this warmer idea mid and late May is on the table. We’re in agreement with the data of a drier than average month.
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.