May is off to a chilly start here in the central United States. Temperatures from Minnesota to north Texas are averaging 5-15 degrees below normal per day!
This morning was downright cold with widespread frost across my local area. Waterloo, Iowa and Freeport, Illinois both dipped to 30. Yikes.
Going forward the signals are strong that blocking in Greenland will keep much of the next 2 weeks below normal. There's one period that looks mild and that's next Tuesday-Wednesday when much of the central Midwest could pulls highs of 70-80 degrees. Otherwise, I see lots of 60s at a time when normal highs have entered the low 70s.
Here are several key teleconnections that point to the predominance of sub-normal temperatures. Until these values climb out of their negative phases (perhaps near the middle of May) the cool will rule. First the AO or Arctic Oscillation.
Now the NAO (North Atlantic Oscillation).
Finally the EPO (eastern Pacific Oscillation).
Here's the CFSv2 5 day temperature departures.
Readings are starting to moderate in the 10-20 day range.
By the end of the month a much warmer pattern is expected to prevail. The 20-30 day departures have totally flipped to warmer and look like this.
Despite the fact readings will be cool by May standards through the weekend, my local area will see plenty of sunshine and welcome dry weather. The GFS rainfall forecast looks this way into Sunday night.
Chilly nights, pleasantly cool days. It'll have to work for now. Roll weather...TS