2018 is already flying! As we welcome in March here are the weather statistics for IND (Indianapolis).
- Average highs start off in the middle 40s on the 1st and rise to the upper 50s on the 31st
- Average lows are in the upper 20s to begin the month and increase to the upper 30s by month’s end
- We average 3.56″ of precipitation, including just under 3″ of snow
Before we look forward to March, let’s review where we’ve been in February. After a very cold start to the month, eastern ridging really flexed it’s muscle and resulted in spring-like conditions for the better part of the past couple weeks. As we type this up late on the 28th, IND is running 5° warmer than average. (It’s been a wet month, too, as we’re close to 2.5″ above normal in the precipitation department).
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.
We note the (2) main drivers this time of year (the AO and NAO) are running negative through mid-month, which favors cold.
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.
Finally, looking ahead, there’s an argument that can be made that we flip the script towards milder times through the last (10) days, or so, of March. We note (as shown above) the AO and NAO trend neutral-to-positive mid and late March. Secondly, the EPO is also expected to flip positive for the second half of the month and this is warm signal, locally, as shown. Majority of guidance also takes the MJO into the “null” phase late 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.
Embedded thunderstorms may target southern Indiana late tonight and Friday morning before more widespread thunderstorms (a couple could become strong) Saturday. The Storm Prediction Center (SPC) has included the southern half of the state in a “marginal risk” of severe thunderstorms Saturday.
All total, additional rainfall between now and Sunday morning should reach 2″ to 3″ across a widespread portion of the southern half of Indiana with locally heavier amounts.
We’ll finally dry things out as we close the weekend and head into early next week as high pressure settles overhead.
Next week will begin a pattern transition from the unseasonably warm weather we’ve enjoyed as of late to a colder regime for the first half of March. We note models continue to tank the NAO and AO.
Accordingly, the models are seeing the trough and associated colder than average pattern returning to the eastern half of the country as we rumble through the first half of March. With such a strong block in place, this can turn into an active pattern for a couple weeks to go along with the cold. Both the GEFS and EPS agree on the overall look.
While there’s no way to get specific on the individual storm threats that will eventually come with this pattern, the potential is present for a few storms to “bowl” underneath the block through the first 10-15 days of the month. Each storm will have the capability of delivering wintry precipitation, but this can also be a tricky time of year where most, if not all, ingredients need to come together to create significant wintry events. In a winter that’s been frustrating to central Indiana snow lovers (frigid, but dry first half and milder, wetter second half), perhaps it would be fitting to get a couple good snow dumps in March (when most are wanting and ready for spring)…
As we look at today’s MJO plot note how we’ve meandered about Phase 7 much longer than initially expected. Also (still) note the attempt to move into the colder phases towards the end of the period, which we’ll talk about here in a bit.
The result has been a cold north-central that has “bled” into the Ohio Valley, while the immediate eastern seaboard and especially southeast has already gotten off to a warm to blow torch start to the month.
Looking ahead, there’s no denying the overall warm pattern (relatively speaking) over the upcoming couple weeks. Phase 7 will continue to do work on the pattern.
Obviously this is right in the heart of when we thought the colder MJO phases would combine with favorably cold teleconnection signals to produce a period of frigid weather. Instead, cold shots will be fleeting and any sort of winter weather threats of significance will be few and far between over the next 10-14 days. In short, Phase 7 will overrule the colder teleconnection signals that will evolve over the period.
Looking ahead, a rather prolonged and significant snow event is setting up shop across northern Indiana. We forecast snow to begin falling Thursday night before becoming heavy at times Friday. A tight thermal gradient will aid in the combination of ingredients to produce hefty snowfall across far northern IN and also provide a brief break from the cold, locally, Friday afternoon (forecasting highs into the 40s here). With that said, if your travels take you north, prepare for significant travel disruptions with the heavy snow.
A cold front will drop south into central Indiana overnight Friday into Saturday. At the same time, a couple of disturbances will ride northeast along the front. This will result in periods of light wintry precipitation across central Indiana over the upcoming weekend. Initially, this should be rather insignificant with a mix of light rain and perhaps some light sleet or light freezing rain Saturday.
However, as our airmass becomes progressively colder Saturday night into Sunday things will become more interesting. At the same time, a final wave of energy will lift northeast, spreading moisture into the colder air mass. We forecast more widespread wintry precipitation to engulf central Indiana Saturday night into Sunday. A wintry mix of sleet and snow is possible early on before transitioning to all snow Sunday morning. A period of accumulating snow is expected Sunday and we’ll fine tune numbers as we move closer.
Looking further ahead, an active time of things will continue as the battle remains between cold centering itself across the northern Plains into the Lakes and Ohio Valley and resistance from the southeast ridge. This will continue to lead to a busy period of weather across the region, including storm systems that will come along every couple of days.
We continue to think things are aligning in a fashion that should result in a significant period of cold developing during the second half of February into March this year. We note the teleconnections continue to trend in cold directions and the MJO is also rolling along into the colder phases. We have a long, long ways to go this winter and think some headline events remain on the table as we close the month and open March. Time will tell.