Since the breakdown of stratospheric polar vortex more high-latitude blocking has become common the last few weeks. Model and ensemble guidance are again showing blocking returning again for next week. But will it give pattern change featuring just below average temperatures? Or will a parade of systems coming out the Pacific, cause the Southeast ridge to build more?
After much warmer than normal temperatures during March, April has averaged cooler than normal so far, with some unseasonable cold weather for some days. This weather might seem bit ironic since we’re moving further into the Spring season. Some major league baseball games have to been postponed due to more unseasonably cold weather and even wintry precipitation in Northern parts of the nation. There are signs of a warming trend going into this weekend and early next week. But there are signs that this may be interrupted again due largely to high-latitude blocking.
Later this week, a large, deep cut-off low over the Rockies will cause a strong ridge to build over the Great Lakes and Ohio Valley regions. Another cut-off low will form on the downstream side of the ridge, off the East Coast. Initially, model guidance showed this cut-off low backing towards the region and affecting our weather this weekend. But high-latitude blocking weakening this week allows this low to remain farther offshore.
The irony of this post, as we write it, is the fact that temperatures are currently surging into the upper 60’s and lower 70’s. A warm airmass is in place, and even behind some rain which fell this morning, highs will reach well above normal. Playoff hockey is just a few weeks away, as is opening day in Major League Baseball. Mother nature, however, has other plans — and she doesn’t seem ready to cooperate with the calendar just yet, as it flips to April.
A major transition in the atmospheric pattern throughout the northern hemisphere will begin next week. On Monday a fairly weak and fast moving storm system will move through the area, with some rainfall anticipated. Behind this storm system will be a Canadian airmass with temperatures perhaps slightly below normal for Tuesday. Model and ensemble guidance indicate a -EPO ridge developing over the Northeast Pacific and Alaska region for middle on next week. This ridge will cause energy to dig and cut over the Southwest United States. Heights will build over Central and Eastern United States with fair weather in local region Wednesday and Thursday. Temperatures will likely rise to above normal levels again during the later part of next week.
In the world of meteorology, Spring begins on March 1st. While the calendar doesn’t turn until the end of the month, meteorologists end winter statistics on the last day of February. Some winters, however, have featured major cold or snowstorms well into March and even April. Remember last year? Still, a year makes a big difference, as they say, and there are growing signs that after this week, cold and snow will become increasingly unlikely.
Looking back at February, temperatures will likely average above normal throughout the area. While we saw the first below zero temperatures in New York City in over two decades on Valentines Day, much of this month featured near or above average temperatures. Artic cold airmasses didn’t hang around for more than a few days. A couple of winter storms we saw earlier in the month tracked too far east to give the entire region of significant snowfall. And in the past two weeks, we have seen a storm track farther west with warmer air and heavy rainfall, as cold air moves in behind the storms.