This Easter on April 20 is the latest the holiday has fallen since 2011 (April 25 is the latest possible in the Julian calendar). So you would expect to have generally mild holiday weather on such a late date, right?
Never assume anything, especially when nature is so fickle as it's been this year.
Columbus broke a record on Friday for the coolest April 18th ever, in terms of maximum temperature. It never got out of the mid-50s all day, though the 60º reading at 2:14 AM will go into the books as the daily high. That still beats the old record of 62º set in 1983. On top of that, it was very wet and very windy - the airport reported 2.60" rain and a peak wind gust of 28 miles per hour during the day.
This is late April, so what in the name of the Easter Bunny is going on? The simple explanation is the cold-air damming wedge that got locked in over Georgia on Friday, combined with low pressure that formed in the northern Gulf to bring copious amounts of rain to our area. Such setups do occur every now and then but are rare.
We knew all week this would be a tricky system. I was off forecasting duty Thursday and Friday, but early in the week it was clear the models were having difficulty resolving the evolution of the surface low and the high that provided the chilly air. I talked on the air about that uncertainty. One general forecast as late as Wednesday was calling for about a quarter-inch of rain here, and there appeared to be some chance we could get missed by the system altogether. By Thursday night, though, it was clear we'd be in the thick of things.
The real issues, though, lay in the upper levels of the atmosphere. This map shows a "cut-off" upper low at around the 18,000 foot altitude (500 millibar level) as analyzed this Saturday morning. We call it cut off because it's a low pressure wave with a full circulation around it. By cutting off rather than moving along as an "open" wave, it caused the whole system to slow down and the surface low to develop far enough north to put us right in the heavy rain.
And that leads to the Easter forecast. Had this system not cut off, we'd be looking at a nice, sunny Saturday and almost certainly a much warmer day, as drier air would have pushed out the cloud deck, clearing our skies. Then a beautiful sunny Easter Sunday would follow.
Saturday afternoon daylight image Surface map
The sunshine is not very far away as I type this (see visible satellite image from Saturday noon) but the winds around the low keep sending clouds back west and keeping us overcast and still unseasonably cool. Even Sunday is looking a bit shaky at this point, though the models do try and clear us out tonight. If we can get the sun out for much of the day, watch temperatures soar into the 70s in the afternoon. We appear to be transitioning into a warm pattern, which should put us back in the 80s later in the week.
It will also give us a chance to dry out a bit - we have certainly seen a wet start to our year, which is a very good thing to happen early in the growing season. April has brought 7.95" of rain to Columbus (8.25" in my own gauge) and we're not even two-thirds of the way through the month yet. This is already the wettest April I've seen in my 25 years in Columbus, and the wettest since 1982 when we had 8.42". (The April record is 11.67" in 1953, which must have been a really rough spring: on April 18, Columbus had its worst tornado to ever strike the city, and three days later the latest recorded freeze.)
So once we get the sunshine back, it should stick around awhile, leaving us with a nice stretch of lows in the 50s and highs topping 80 this week. I think we can manage that quite nicely.