Posted at: 05/23/2013 8:43 PM
Updated at: 05/23/2013 9:18 PM
Another Active, Wet Stretch Ahead
This month is already one for the record books and not just for rain either! Here's where we've been so far. There has been record snow, record precipitation, record highs and even record lows all in a span of three weeks.
This May is the wettest May since records began being kept in 1886 with 8.63" of rain so far. Not only is it the wettest May, it's also the 14th wettest month ever recorded. And it's only going to climb the list.
Fresh off a long very soggy stretch that brought flash flooding to some spots over the weekend, another persistent wet streak is moving in beginning Friday night and it's a pattern that doesn't look to break until, at minimum, NEXT weekend. Why? It's a virtual traffic jam 15,000 to 30,000 feet in the air. Here's a look at the 500 mb level in the atmosphere, about 18,000 feet up. At our latitude on earth the trade winds generally flow west to east, progressive enough to keep storms moving across the country at a decent clip, usually traversing the country in three to four days. With what's going on currently, the trade winds (red line) are all kinked up, instead of running west to east, running a lot of north to south as well.
This means a storm system, trying to develop back to our west will struggle to move and continue to send waves of rain our way. Here's the storm's position at the surface on Saturday morning, around the time the first wave of rain will hit.
The same storm by next Friday afternoon... hasn't moved much.
This is a situation meteorologists call a cut-off low... cutoff from the jet stream which normally carries the storms progressively through the area. Right now a cut-off low is the last thing we need.
With a ground already soaked and fresh off flooding, we are again primed for flash flooding if high rainfall rates occur. While it's too early to say how much rain will fall during the next week, the computer models are hinting at another significant amount of rain in the next week. The model at right is calling for 2 to 4" of rainfall across SE Minnesota and North Iowa from now through May 31st.
Now that's not a forecast and the model isn't fine enough to pick up on small individual thunderstorms that may produce high rainfall rates. (like the one's last Sunday that pumped out 5-6" of rain while the surrounding area was closer to 1-2") We'll need to track the day to day fluctuations as we head into the stretch. But it is a hint that we may not be done with significant rains this May. The May that just keeps blasting records, climbing lists, becoming engrained in memories.
Is there a sign of the pattern breaking? Not anytime soon. It's beginning to look more and more like our next completely dry midnight to midnight stretch won't come until at least June.
-Storm Tracker 6 Chief Meteorologist