Take April, for example. Despite some chill here and there, and even a rare late-season Appalachian snowstorm, it was warmer than average in almost all 50 states. And in many locations in the middle third of the nation, a lot (>4°F) warmer.

Temperature departures from normal, averaged over 1st week of May (Image courtesy CPC/NOAA.)

Will the streak of warm months continue?

Temperature departures from normal expected this Friday, from GFS ensemble mean. (Penn State)

This week highs will be in the 60s in the Great Lakes (sound like March?), and barely warmer than that Thursday and Friday in the mid-Atlantic. In addition, the cooler weather will greatly reduce the prospects for severe weather for a while, as the transport of humid air from the Gulf of Mexico into the Lower 48 shuts down temporarily.

High-altitude winds expected Thursday. Jet stream is outlined by yellow arrows. (FNMOC)

But as we look ahead into next week, and into the last half of the month, the jet stream over the Western Hemisphere will likely reorganize itself in association with the return of above-normal temperatures nearly nationwide. There is some suggestion that a broad southwesterly flow will gradually resume its course over the United States in 1-2 weeks (shown to the right below).

High-altitude temperatures and winds expected late next week by the ECMWF weather model. Arrow identifies the jet stream (Penn State)