Welcome to May Day but the chill is still here!

 

I’ve been getting quite a few inquiries on when we are going to warm up. So, here’s a post that will try to answer that.

The surface chart and radar

The calendar says it’s May; but the temperatures are saying that isn’t true. In spite of us moving deeper into Spring, the pattern is going to go in the opposite direction.  While the polar vortex is over, it’s aftereffects are not.

 Why is it so cold?

We have a strong cold front tracking eastward across the United States, the front is causing a big drop in temperatures from the Plains to the East.  The system is bringing a sharp break from the recent conditions, where temperatures were very mild, allowing the trees to start budding.

 

Image curtesy of Tropical Tidbits

The change is being driven by a deep dip in the jet stream. This is allowing much cooler air to dive south out of Canada. As the bend in the jet stream is funneling that polar air mass into the eastern 2/3 of the Continental US (CONUS) This is going to continue as we move farther into May.

That storm system is doing more than just pushing the cold front through; the slow-moving system that is riding along the jet stream is reenforcing the colder air already in place, helping reinforce the cooler pattern and making it hard to dislodge. The change is being driven by a deep dip in the jet stream, which is allowing a surge of cooler air to move south out of Canada.

When will temperatures warm back up?

Here is a look at the Long-range outlook from NOAA. This is covering from early to mid-May.

 

We can see it's continuing to signal below-average temperatures across the central and eastern U.S. The Jet is going to stay active with dips in the Jet. Resulting in reenforcing shots of colder air. Remember that doesn’t necessarily mean it we will see cold or freezing air all the time, but rather some warmth between these cold shots.

 

Overall, moving forward we look to see a gradual, uneven warm-up where overall we’re colder than average, but should see seasonable or higher-than-average average temperatures at times. rather than sustained warmer temperature through at least mid-May. The second half of May doesn’t look to be as cold as the first half across our region as well as the East in general, but an abrupt swing into summerlike warmth is looking very unlikely. I’ve been talking about this pattern for the last few months. In the Spring Outlook a said overall this spring could say overall cool.