Enjoy the above average temperatures this week because the medium range forecast models continue to suggest The Mid-Atlantic may experience below average temperatures the second half of April.
The North Atlantic Oscillation (image below, courtesy The Weather Channel) continues to trend negative, meaning that an upper-level ridge of high pressure is forecast to build across Greenland and the Canadian Maritime.
This upper-level ridge of high pressure acts as a block causing the jet stream to buckle further south into the eastern United States bringing below-average temperatures.
The next image (courtesy Pivotal Weather) shows the 500 millibar (mb) height anomalies through April 15. You’ll notice the bright red and orange colors holding strong from the eastern Hudson Bay of Canada toward Greenland, indicative of the upper-level blocking that I just mentioned.